sched/topology: Fix sched_numa_find_nth_cpu() in non-NUMA case

When CONFIG_NUMA is enabled, sched_numa_find_nth_cpu() searches for a
CPU in sched_domains_numa_masks. The masks includes only online CPUs,
so effectively offline CPUs are skipped.

When CONFIG_NUMA is disabled, the fallback function should be consistent.

Fixes: cd7f55359c90 ("sched: add sched_numa_find_nth_cpu()")
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20230819141239.287290-5-yury.norov@gmail.com

sched/topology: Introduce for_each_numa_hop_mask()

The recently introduced sched_numa_hop_mask() exposes cpumasks of CPUs
reachable within a given distance budget, wrap the logic for iterating over
all (distance, mask) values inside an iterator macro.

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sched/topology: Introduce sched_numa_hop_mask()

Tariq has pointed out that drivers allocating IRQ vectors would benefit
from having smarter NUMA-awareness - cpumask_local_spread() only knows
about the local node and everything outside is in the same bucket.

sched_domains_numa_masks is pretty much what we want to hand out (a cpumask
of CPUs reachable within a given distance budget), introduce
sched_numa_hop_mask() to export those cpumasks.

Link: http://lore.kernel.org/r/20220728191203.4055-1-tariqt@nvidia.com
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

sched: add sched_numa_find_nth_cpu()

The function finds Nth set CPU in a given cpumask starting from a given
node.

Leveraging the fact that each hop in sched_domains_numa_masks includes the
same or greater number of CPUs than the previous one, we can use binary
search on hops instead of linear walk, which makes the overall complexity
of O(log n) in terms of number of cpumask_weight() calls.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Peter Lafreniere <peter@n8pjl.ca>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

topology: Remove unused cpu_cluster_mask()

default_topology[] uses cpu_clustergroup_mask() for the CLS level
(guarded by CONFIG_SCHED_CLUSTER) which is currently provided by x86
(arch/x86/kernel/smpboot.c) and arm64 (drivers/base/arch_topology.c).

Fixes: 778c558f49a2 ("sched: Add cluster scheduler level in core and related Kconfig for ARM64")
Acked-by: Barry Song <baohua@kernel.org>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20220513093433.425163-1-dietmar.eggemann@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

topology: Remove unused cpu_cluster_mask()

default_topology[] uses cpu_clustergroup_mask() for the CLS level
(guarded by CONFIG_SCHED_CLUSTER) which is currently provided by x86
(arch/x86/kernel/smpboot.c) and arm64 (drivers/base/arch_topology.c).

Fixes: 778c558f49a2c ("sched: Add cluster scheduler level in core and
related Kconfig for ARM64")

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Barry Song <baohua@kernel.org>
Link: https://lore.kernel.org/r/20220513093433.425163-1-dietmar.eggemann@arm.com

topology/sysfs: Add PPIN in sysfs under cpu topology

PPIN is the Protected Processor Identification Number.
This is used to identify the socket as a Field Replaceable Unit (FRU).

Existing code only displays this when reporting errors. But this makes
it inconvenient for large clusters to use it for its intended purpose
of inventory control.

Add ppin to /sys/devices/system/cpu/cpu*/topology to make what
is already available using RDMSR more easily accessible. Make
the file read only for root in case there are still people
concerned about making a unique system "serial number" available.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20220131230111.2004669-6-tony.luck@intel.com

topology/sysfs: rework book and drawer topology ifdefery

Provide default defines for the topology_book_[id|cpumask] and
topology_drawer_[id|cpumask] macros just like for each other topology
level.
This way all topology levels are handled in a similar way. Still the
the book and drawer levels are only used on s390, and also the sysfs
attributes are only created on s390. However other architectures may
opt in if wanted.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20211129130309.3256168-4-hca@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

topology/sysfs: export cluster attributes only if an architectures has support

The cluster_id and cluster_cpus topology sysfs attributes have been
added with commit c5e22feffdd7 ("topology: Represent clusters of CPUs
within a die").

They are currently only used for x86, arm64, and riscv (via generic
arch topology), however they are still present with bogus default
values for all other architectures. Instead of enforcing such new
sysfs attributes to all architectures, make them only optional visible
if an architecture opts in by defining both the topology_cluster_id
and topology_cluster_cpumask attributes.

This is similar to what was done when the book and drawer topology
levels were introduced: avoid useless and therefore confusing sysfs
attributes for architectures which cannot make use of them.

This should not break any existing applications, since this is a
new interface introduced with the v5.16 merge window.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20211129130309.3256168-3-hca@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

topology/sysfs: export die attributes only if an architectures has support

The die_id and die_cpus topology sysfs attributes have been added with
commit 0e344d8c709f ("cpu/topology: Export die_id") and commit
2e4c54dac7b3 ("topology: Create core_cpus and die_cpus sysfs attributes").

While they are currently only used and useful for x86 they are still
present with bogus default values for all architectures. Instead of
enforcing such new sysfs attributes to all architectures, make them
only optional visible if an architecture opts in by defining both the
topology_die_id and topology_die_cpumask attributes.

This is similar to what was done when the book and drawer topology
levels were introduced: avoid useless and therefore confusing sysfs
attributes for architectures which cannot make use of them.

This should not break any existing applications, since this is a
rather new interface and applications should be able to handle also
older kernel versions without such attributes - besides that they
contain only useful information for x86.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20211129130309.3256168-2-hca@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sched: Add cluster scheduler level in core and related Kconfig for ARM64

This patch adds scheduler level for clusters and automatically enables
the load balance among clusters. It will directly benefit a lot of
workload which loves more resources such as memory bandwidth, caches.

Testing has widely been done in two different hardware configurations of
Kunpeng920:

24 cores in one NUMA(6 clusters in each NUMA node);
32 cores in one NUMA(8 clusters in each NUMA node)

Workload is running on either one NUMA node or four NUMA nodes, thus,
this can estimate the effect of cluster spreading w/ and w/o NUMA load
balance.

* Stream benchmark:

4threads stream (on 1NUMA * 24cores = 24cores)
stream stream
w/o patch w/ patch
MB/sec copy 29929.64 ( 0.00%) 32932.68 ( 10.03%)
MB/sec scale 29861.10 ( 0.00%) 32710.58 ( 9.54%)
MB/sec add 27034.42 ( 0.00%) 32400.68 ( 19.85%)
MB/sec triad 27225.26 ( 0.00%) 31965.36 ( 17.41%)

6threads stream (on 1NUMA * 24cores = 24cores)
stream stream
w/o patch w/ patch
MB/sec copy 40330.24 ( 0.00%) 42377.68 ( 5.08%)
MB/sec scale 40196.42 ( 0.00%) 42197.90 ( 4.98%)
MB/sec add 37427.00 ( 0.00%) 41960.78 ( 12.11%)
MB/sec triad 37841.36 ( 0.00%) 42513.64 ( 12.35%)

12threads stream (on 1NUMA * 24cores = 24cores)
stream stream
w/o patch w/ patch
MB/sec copy 52639.82 ( 0.00%) 53818.04 ( 2.24%)
MB/sec scale 52350.30 ( 0.00%) 53253.38 ( 1.73%)
MB/sec add 53607.68 ( 0.00%) 55198.82 ( 2.97%)
MB/sec triad 54776.66 ( 0.00%) 56360.40 ( 2.89%)

Thus, it could help memory-bound workload especially under medium load.
Similar improvement is also seen in lkp-pbzip2:

* lkp-pbzip2 benchmark

2-96 threads (on 4NUMA * 24cores = 96cores)
lkp-pbzip2 lkp-pbzip2
w/o patch w/ patch
Hmean tput-2 11062841.57 ( 0.00%) 11341817.51 * 2.52%*
Hmean tput-5 26815503.70 ( 0.00%) 27412872.65 * 2.23%*
Hmean tput-8 41873782.21 ( 0.00%) 43326212.92 * 3.47%*
Hmean tput-12 61875980.48 ( 0.00%) 64578337.51 * 4.37%*
Hmean tput-21 105814963.07 ( 0.00%) 111381851.01 * 5.26%*
Hmean tput-30 150349470.98 ( 0.00%) 156507070.73 * 4.10%*
Hmean tput-48 237195937.69 ( 0.00%) 242353597.17 * 2.17%*
Hmean tput-79 360252509.37 ( 0.00%) 362635169.23 * 0.66%*
Hmean tput-96 394571737.90 ( 0.00%) 400952978.48 * 1.62%*

2-24 threads (on 1NUMA * 24cores = 24cores)
lkp-pbzip2 lkp-pbzip2
w/o patch w/ patch
Hmean tput-2 11071705.49 ( 0.00%) 11296869.10 * 2.03%*
Hmean tput-4 20782165.19 ( 0.00%) 21949232.15 * 5.62%*
Hmean tput-6 30489565.14 ( 0.00%) 33023026.96 * 8.31%*
Hmean tput-8 40376495.80 ( 0.00%) 42779286.27 * 5.95%*
Hmean tput-12 61264033.85 ( 0.00%) 62995632.78 * 2.83%*
Hmean tput-18 86697139.39 ( 0.00%) 86461545.74 ( -0.27%)
Hmean tput-24 104854637.04 ( 0.00%) 104522649.46 * -0.32%*

In the case of 6 threads and 8 threads, we see the greatest performance
improvement.

Similar improvement can be seen on lkp-pixz though the improvement is
smaller:

* lkp-pixz benchmark

2-24 threads lkp-pixz (on 1NUMA * 24cores = 24cores)
lkp-pixz lkp-pixz
w/o patch w/ patch
Hmean tput-2 6486981.16 ( 0.00%) 6561515.98 * 1.15%*
Hmean tput-4 11645766.38 ( 0.00%) 11614628.43 ( -0.27%)
Hmean tput-6 15429943.96 ( 0.00%) 15957350.76 * 3.42%*
Hmean tput-8 19974087.63 ( 0.00%) 20413746.98 * 2.20%*
Hmean tput-12 28172068.18 ( 0.00%) 28751997.06 * 2.06%*
Hmean tput-18 39413409.54 ( 0.00%) 39896830.55 * 1.23%*
Hmean tput-24 49101815.85 ( 0.00%) 49418141.47 * 0.64%*

* SPECrate benchmark

4,8,16 copies mcf_r(on 1NUMA * 32cores = 32cores)
Base Base
Run Time Rate
------- ---------
4 Copies w/o 580 (w/ 570) w/o 11.1 (w/ 11.3)
8 Copies w/o 647 (w/ 605) w/o 20.0 (w/ 21.4, +7%)
16 Copies w/o 844 (w/ 844) w/o 30.6 (w/ 30.6)

32 Copies(on 4NUMA * 32 cores = 128cores)
[w/o patch]
Base Base Base
Benchmarks Copies Run Time Rate
--------------- ------- --------- ---------
500.perlbench_r 32 584 87.2 *
502.gcc_r 32 503 90.2 *
505.mcf_r 32 745 69.4 *
520.omnetpp_r 32 1031 40.7 *
523.xalancbmk_r 32 597 56.6 *
525.x264_r 1 -- CE
531.deepsjeng_r 32 336 109 *
541.leela_r 32 556 95.4 *
548.exchange2_r 32 513 163 *
557.xz_r 32 530 65.2 *
Est. SPECrate2017_int_base 80.3

[w/ patch]
Base Base Base
Benchmarks Copies Run Time Rate
--------------- ------- --------- ---------
500.perlbench_r 32 580 87.8 (+0.688%) *
502.gcc_r 32 477 95.1 (+5.432%) *
505.mcf_r 32 644 80.3 (+13.574%) *
520.omnetpp_r 32 942 44.6 (+9.58%) *
523.xalancbmk_r 32 560 60.4 (+6.714%%) *
525.x264_r 1 -- CE
531.deepsjeng_r 32 337 109 (+0.000%) *
541.leela_r 32 554 95.6 (+0.210%) *
548.exchange2_r 32 515 163 (+0.000%) *
557.xz_r 32 524 66.0 (+1.227%) *
Est. SPECrate2017_int_base 83.7 (+4.062%)

On the other hand, it is slightly helpful to CPU-bound tasks like
kernbench:

* 24-96 threads kernbench (on 4NUMA * 24cores = 96cores)
kernbench kernbench
w/o cluster w/ cluster
Min user-24 12054.67 ( 0.00%) 12024.19 ( 0.25%)
Min syst-24 1751.51 ( 0.00%) 1731.68 ( 1.13%)
Min elsp-24 600.46 ( 0.00%) 598.64 ( 0.30%)
Min user-48 12361.93 ( 0.00%) 12315.32 ( 0.38%)
Min syst-48 1917.66 ( 0.00%) 1892.73 ( 1.30%)
Min elsp-48 333.96 ( 0.00%) 332.57 ( 0.42%)
Min user-96 12922.40 ( 0.00%) 12921.17 ( 0.01%)
Min syst-96 2143.94 ( 0.00%) 2110.39 ( 1.56%)
Min elsp-96 211.22 ( 0.00%) 210.47 ( 0.36%)
Amean user-24 12063.99 ( 0.00%) 12030.78 * 0.28%*
Amean syst-24 1755.20 ( 0.00%) 1735.53 * 1.12%*
Amean elsp-24 601.60 ( 0.00%) 600.19 ( 0.23%)
Amean user-48 12362.62 ( 0.00%) 12315.56 * 0.38%*
Amean syst-48 1921.59 ( 0.00%) 1894.95 * 1.39%*
Amean elsp-48 334.10 ( 0.00%) 332.82 * 0.38%*
Amean user-96 12925.27 ( 0.00%) 12922.63 ( 0.02%)
Amean syst-96 2146.66 ( 0.00%) 2122.20 * 1.14%*
Amean elsp-96 211.96 ( 0.00%) 211.79 ( 0.08%)

Note this patch isn't an universal win, it might hurt those workload
which can benefit from packing. Though tasks which want to take
advantages of lower communication latency of one cluster won't
necessarily been packed in one cluster while kernel is not aware of
clusters, they have some chance to be randomly packed. But this
patch will make them more likely spread.

Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Tested-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

topology: Represent clusters of CPUs within a die

Both ACPI and DT provide the ability to describe additional layers of
topology between that of individual cores and higher level constructs
such as the level at which the last level cache is shared.
In ACPI this can be represented in PPTT as a Processor Hierarchy
Node Structure [1] that is the parent of the CPU cores and in turn
has a parent Processor Hierarchy Nodes Structure representing
a higher level of topology.

For example Kunpeng 920 has 6 or 8 clusters in each NUMA node, and each
cluster has 4 cpus. All clusters share L3 cache data, but each cluster
has local L3 tag. On the other hand, each clusters will share some
internal system bus.

+-----------------------------------+ +---------+
| +------+ +------+ +--------------------------+ |
| | CPU0 | | cpu1 | | +-----------+ | |
| +------+ +------+ | | | | |
| +----+ L3 | | |
| +------+ +------+ cluster | | tag | | |
| | CPU2 | | CPU3 | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | |
+-----------------------------------+ | |
| +------+ +------+ +--------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| | | L3 | | |
| +------+ +------+ +----+ tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | L3 |
| data |
+-----------------------------------+ | |
| +------+ +------+ | +-----------+ | |
| | | | | | | | | |
| +------+ +------+ +----+ L3 | | |
| | | tag | | |
| +------+ +------+ | | | | |
| | | | | | +-----------+ | |
| +------+ +------+ +--------------------------+ |
+-----------------------------------| | |
+-----------------------------------| | |
| +------+ +------+ +--------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| +----+ L3 | | |
| +------+ +------+ | | tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | |
+-----------------------------------+ | |
| +------+ +------+ +--------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| | | L3 | | |
| +------+ +------+ +---+ tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | | |
+-----------------------------------+ | |
+-----------------------------------+ | |
| +------+ +------+ +--------------------------+ |
| | | | | | +-----------+ | |
| +------+ +------+ | | | | |
| | | L3 | | |
| +------+ +------+ +--+ tag | | |
| | | | | | | | | |
| +------+ +------+ | +-----------+ | |
| | +---------+
+-----------------------------------+

That means spreading tasks among clusters will bring more bandwidth
while packing tasks within one cluster will lead to smaller cache
synchronization latency. So both kernel and userspace will have
a chance to leverage this topology to deploy tasks accordingly to
achieve either smaller cache latency within one cluster or an even
distribution of load among clusters for higher throughput.

This patch exposes cluster topology to both kernel and userspace.
Libraried like hwloc will know cluster by cluster_cpus and related
sysfs attributes. PoC of HWLOC support at [2].

Note this patch only handle the ACPI case.

Special consideration is needed for SMT processors, where it is
necessary to move 2 levels up the hierarchy from the leaf nodes
(thus skipping the processor core level).

Note that arm64 / ACPI does not provide any means of identifying
a die level in the topology but that may be unrelate to the cluster
level.

[1] ACPI Specification 6.3 - section 5.2.29.1 processor hierarchy node
structure (Type 0)
[2] https://github.com/hisilicon/hwloc/tree/linux-cluster

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210924085104.44806-2-21cnbao@gmail.com

sched/topology: Make sched_init_numa() use a set for the deduplicating sort

The deduplicating sort in sched_init_numa() assumes that the first line in
the distance table contains all unique values in the entire table. I've
been trying to pen what this exactly means for the topology, but it's not
straightforward. For instance, topology.c uses this example:

node 0 1 2 3
0: 10 20 20 30
1: 20 10 20 20
2: 20 20 10 20
3: 30 20 20 10

0 ----- 1
| / |
| / |
| / |
2 ----- 3

Which works out just fine. However, if we swap nodes 0 and 1:

1 ----- 0
| / |
| / |
| / |
2 ----- 3

we get this distance table:

node 0 1 2 3
0: 10 20 20 20
1: 20 10 20 30
2: 20 20 10 20
3: 20 30 20 10

Which breaks the deduplicating sort (non-representative first line). In
this case this would just be a renumbering exercise, but it so happens that
we can have a deduplicating sort that goes through the whole table in O(n²)
at the extra cost of a temporary memory allocation (i.e. any form of set).

The ACPI spec (SLIT) mentions distances are encoded on 8 bits. Following
this, implement the set as a 256-bits bitmap. Should this not be
satisfactory (i.e. we want to support 32-bit values), then we'll have to go
for some other sparse set implementation.

This has the added benefit of letting us allocate just the right amount of
memory for sched_domains_numa_distance[], rather than an arbitrary
(nr_node_ids + 1).

Note: DT binding equivalent (distance-map) decodes distances as 32-bit
values.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210122123943.1217-2-valentin.schneider@arm.com

sched/topology: Allow archs to override cpu_smt_mask

cpu_smt_mask tracks topology_sibling_cpumask. This would be good for
most architectures. One of the users of cpu_smt_mask(), would be to
identify idle-cores. On Power9, a pair of SMT4 cores can be presented
by the firmware as a SMT8 core for backward compatibility reasons.

powerpc allows LPARs to be live migrated from Power8 to Power9. Do
note Power8 had only SMT8 cores. Existing software which has been
developed/configured for Power8 would expect to see SMT8 core.
Maintaining the illusion of SMT8 core is a requirement to make that
work.

In order to maintain above userspace backward compatibility with
previous versions of processor, Power9 onwards there is option to the
firmware to advertise a pair of SMT4 cores as a fused cores aka SMT8
core. On Power9 this pair shares the L2 cache as well. However, from
the scheduler's point of view, a core should be determined by SMT4,
since its a completely independent unit of compute. Hence allow
powerpc architecture to override the default cpu_smt_mask() to point
to the SMT4 cores in a SMT8 mode.

This will ensure the scheduler is always given the right information.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200807074517.27957-1-srikar@linux.vnet.ibm.com

revert "topology: add support for node_to_mem_node() to determine the fallback node"

This reverts commit ad2c8144418c6a81cefe65379fd47bbe8344cef2.

The function node_to_mem_node() was introduced by that commit for use in SLUB
on systems with memoryless nodes, but it turned out to be unreliable on some
architectures/configurations and a simpler solution exists than fixing it up.

Thus commit 0715e6c516f1 ("mm, slub: prevent kmalloc_node crashes and
memory leaks") removed the only user of node_to_mem_node() and we can
revert the commit that introduced the function.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: PUVICHAKRAVARTHY RAMACHANDRAN <puvichakravarthy@in.ibm.com>
Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20200320115533.9604-2-vbabka@suse.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched/topology: Improve load balancing on AMD EPYC systems

SD_BALANCE_{FORK,EXEC} and SD_WAKE_AFFINE are stripped in sd_init()
for any sched domains with a NUMA distance greater than 2 hops
(RECLAIM_DISTANCE). The idea being that it's expensive to balance
across domains that far apart.

However, as is rather unfortunately explained in:

commit 32e45ff43eaf ("mm: increase RECLAIM_DISTANCE to 30")

the value for RECLAIM_DISTANCE is based on node distance tables from
2011-era hardware.

Current AMD EPYC machines have the following NUMA node distances:

node distances:
node 0 1 2 3 4 5 6 7
0: 10 16 16 16 32 32 32 32
1: 16 10 16 16 32 32 32 32
2: 16 16 10 16 32 32 32 32
3: 16 16 16 10 32 32 32 32
4: 32 32 32 32 10 16 16 16
5: 32 32 32 32 16 10 16 16
6: 32 32 32 32 16 16 10 16
7: 32 32 32 32 16 16 16 10

where 2 hops is 32.

The result is that the scheduler fails to load balance properly across
NUMA nodes on different sockets -- 2 hops apart.

For example, pinning 16 busy threads to NUMA nodes 0 (CPUs 0-7) and 4
(CPUs 32-39) like so,

$ numactl -C 0-7,32-39 ./spinner 16

causes all threads to fork and remain on node 0 until the active
balancer kicks in after a few seconds and forcibly moves some threads
to node 4.

Override node_reclaim_distance for AMD Zen.

Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suravee.Suthikulpanit@amd.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas.Lendacky@amd.com
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20190808195301.13222-3-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>

cpu-topology: Move cpu topology code to common code.

Both RISC-V & ARM64 are using cpu-map device tree to describe
their cpu topology. It's better to move the relevant code to
a common place instead of duplicate code.

To: Will Deacon <will.deacon@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
[Tested on QDF2400]
Tested-by: Jeffrey Hugo <jhugo@codeaurora.org>
[Tested on Juno and other embedded platforms.]
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

topology: Create core_cpus and die_cpus sysfs attributes

Create CPU topology sysfs attributes: "core_cpus" and "core_cpus_list"

These attributes represent all of the logical CPUs that share the
same core.

These attriutes is synonymous with the existing "thread_siblings" and
"thread_siblings_list" attribute, which will be deprecated.

Create CPU topology sysfs attributes: "die_cpus" and "die_cpus_list".
These attributes represent all of the logical CPUs that share the
same die.

Suggested-by: Brice Goglin <Brice.Goglin@inria.fr>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/071c23a298cd27ede6ed0b6460cae190d193364f.1557769318.git.len.brown@intel.com

cpu/topology: Export die_id

Export die_id in cpu topology, for the benefit of hardware that has
multiple-die/package.

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-doc@vger.kernel.org
Link: https://lkml.kernel.org/r/e7d1caaf4fbd24ee40db6d557ab28d7d83298900.1557769318.git.len.brown@intel.com

mm: convert zone_reclaim to node_reclaim

As reclaim is now per-node based, convert zone_reclaim to be
node_reclaim. It is possible that a node will be reclaimed multiple
times if it has multiple zones but this is unavoidable without caching
all nodes traversed so far. The documentation and interface to
userspace is the same from a configuration perspective and will will be
similar in behaviour unless the node-local allocation requests were also
limited to lower zones.

Link: http://lkml.kernel.org/r/1467970510-21195-24-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

numa: remove stale node_has_online_mem() define

This isn't used anywhere, so delete it.

Looks like the last usage (in x86-specific code) was removed by Tejun
in 2011 in commit bd6709a91a59 ("x86, NUMA: Make 32bit use common NUMA
init path").

Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>

sched/topology: Rename topology_thread_cpumask() to topology_sibling_cpumask()

Rename topology_thread_cpumask() to topology_sibling_cpumask()
for more consistency with scheduler code.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Benoit Cousson <bcousson@baylibre.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jean Delvare <jdelvare@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/1432645896-12588-2-git-send-email-bgolaszewski@baylibre.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

topology: add support for node_to_mem_node() to determine the fallback node

Anton noticed (http://www.spinics.net/lists/linux-mm/msg67489.html) that
on ppc LPARs with memoryless nodes, a large amount of memory was consumed
by slabs and was marked unreclaimable. He tracked it down to slab
deactivations in the SLUB core when we allocate remotely, leading to poor
efficiency always when memoryless nodes are present.

After much discussion, Joonsoo provided a few patches that help
significantly. They don't resolve the problem altogether:

- memory hotplug still needs testing, that is when a memoryless node
becomes memory-ful, we want to dtrt
- there are other reasons for going off-node than memoryless nodes,
e.g., fully exhausted local nodes

Neither case is resolved with this series, but I don't think that should
block their acceptance, as they can be explored/resolved with follow-on
patches.

The series consists of:

[1/3] topology: add support for node_to_mem_node() to determine the
fallback node

[2/3] slub: fallback to node_to_mem_node() node if allocating on
memoryless node

- Joonsoo's patches to cache the nearest node with memory for each
NUMA node

[3/3] Partial revert of 81c98869faa5 (""kthread: ensure locality of
task_struct allocations")

- At Tejun's request, keep the knowledge of memoryless node fallback
to the allocator core.

This patch (of 3):

We need to determine the fallback node in slub allocator if the allocation
target node is memoryless node. Without it, the SLUB wrongly select the
node which has no memory and can't use a partial slab, because of node
mismatch. Introduced function, node_to_mem_node(X), will return a node Y
with memory that has the nearest distance. If X is memoryless node, it
will return nearest distance node, but, if X is normal node, it will
return itself.

We will use this function in following patch to determine the fallback
node.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Han Pingtian <hanpt@linux.vnet.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Anton Blanchard <anton@samba.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: disable zone_reclaim_mode by default

When it was introduced, zone_reclaim_mode made sense as NUMA distances
punished and workloads were generally partitioned to fit into a NUMA
node. NUMA machines are now common but few of the workloads are
NUMA-aware and it's routine to see major performance degradation due to
zone_reclaim_mode being enabled but relatively few can identify the
problem.

Those that require zone_reclaim_mode are likely to be able to detect
when it needs to be enabled and tune appropriately so lets have a
sensible default for the bulk of users.

This patch (of 2):

zone_reclaim_mode causes processes to prefer reclaiming memory from
local node instead of spilling over to other nodes. This made sense
initially when NUMA machines were almost exclusively HPC and the
workload was partitioned into nodes. The NUMA penalties were
sufficiently high to justify reclaiming the memory. On current machines
and workloads it is often the case that zone_reclaim_mode destroys
performance but not all users know how to detect this. Favour the
common case and disable it by default. Users that are sophisticated
enough to know they need zone_reclaim_mode will detect it.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched: Rework sched_domain topology definition

We replace the old way to configure the scheduler topology with a new method
which enables a platform to declare additionnal level (if needed).

We still have a default topology table definition that can be used by platform
that don't want more level than the SMT, MC, CPU and NUMA ones. This table can
be overwritten by an arch which either wants to add new level where a load
balance make sense like BOOK or powergating level or wants to change the flags
configuration of some levels.

For each level, we need a function pointer that returns cpumask for each cpu,
a function pointer that returns the flags for the level and a name. Only flags
that describe topology, can be set by an architecture. The current topology
flags are:

SD_SHARE_CPUPOWER
SD_SHARE_PKG_RESOURCES
SD_NUMA
SD_ASYM_PACKING

Then, each level must be a subset on the next one. The build sequence of the
sched_domain will take care of removing useless levels like those with 1 CPU
and those with the same CPU span and no more relevant information for
load balancing than its children.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux390@de.ibm.com
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Link: http://lkml.kernel.org/r/1397209481-28542-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

mm: use raw_cpu ops for determining current NUMA node

With the preempt checking logic for __this_cpu_ops we will get false
positives from locations in the code that use numa_node_id.

Before the __this_cpu ops where introduced there were no checks for
preemption present either. smp_raw_processor_id() was used. See

http://www.spinics.net/lists/linux-numa/msg00641.html

Therefore we need to use raw_cpu_read here to avoid false postives.

Note that this issue has been discussed in prior years. If the process
changes nodes after retrieving the current numa node then that is
acceptable since most uses of numa_node etc are for optimization and not
for correctness.

There were suggestions to implement a raw_numa_node_id in order to do
preempt checks for numa_node_id as well. But I think we better defer
that to another patch since that would mean investigating how
numa_node_id() is used throughout the kernel which would increase the
scope of this patchset significantly. After all preemption was never
checked before when numa_node_id() was used.

Some sample traces:

__this_cpu_read operation in preemptible [00000000] code: login/1456
caller is __this_cpu_preempt_check+0x2b/0x2d
CPU: 0 PID: 1456 Comm: login Not tainted 3.12.0-rc4-cl-00062-g2fe80d3-dirty #185
Call Trace:
dump_stack+0x4e/0x82
check_preemption_disabled+0xc5/0xe0
__this_cpu_preempt_check+0x2b/0x2d
get_task_policy+0x1d/0x49
get_vma_policy+0x14/0x76
alloc_pages_vma+0x35/0xff
handle_mm_fault+0x290/0x73b
__do_page_fault+0x3fe/0x44d
do_page_fault+0x9/0xc
page_fault+0x22/0x30
generic_file_aio_read+0x38e/0x624
do_sync_read+0x54/0x73
vfs_read+0x9d/0x12a
SyS_read+0x47/0x7e
cstar_dispatch+0x7/0x23

caller is __this_cpu_preempt_check+0x2b/0x2d
CPU: 0 PID: 1456 Comm: login Not tainted 3.12.0-rc4-cl-00062-g2fe80d3-dirty #185
Call Trace:
dump_stack+0x4e/0x82
check_preemption_disabled+0xc5/0xe0
__this_cpu_preempt_check+0x2b/0x2d
alloc_pages_current+0x8f/0xbc
__page_cache_alloc+0xb/0xd
__do_page_cache_readahead+0xf4/0x219
ra_submit+0x1c/0x20
ondemand_readahead+0x28c/0x2b4
page_cache_sync_readahead+0x38/0x3a
generic_file_aio_read+0x261/0x624
do_sync_read+0x54/0x73
vfs_read+0x9d/0x12a
SyS_read+0x47/0x7e
cstar_dispatch+0x7/0x23

Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Alex Shi <alex.shi@intel.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched/balancing: Periodically decay max cost of idle balance

This patch builds on patch 2 and periodically decays that max value to
do idle balancing per sched domain by approximately 1% per second. Also
decay the rq's max_idle_balance_cost value.

Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1379096813-3032-4-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched/balancing: Consider max cost of idle balance per sched domain

In this patch, we keep track of the max cost we spend doing idle load balancing
for each sched domain. If the avg time the CPU remains idle is less then the
time we have already spent on idle balancing + the max cost of idle balancing
in the sched domain, then we don't continue to attempt the balance. We also
keep a per rq variable, max_idle_balance_cost, which keeps track of the max
time spent on newidle load balances throughout all its domains so that we can
determine the avg_idle's max value.

By using the max, we avoid overrunning the average. This further reduces the
chance we attempt balancing when the CPU is not idle for longer than the cost
to balance.

Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1379096813-3032-3-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched: recover SD_WAKE_AFFINE in select_task_rq_fair and code clean up

Since power saving code was removed from sched now, the implement
code is out of service in this function, and even pollute other logical.
like, 'want_sd' never has chance to be set '0', that remove the effect
of SD_WAKE_AFFINE here.

So, clean up the obsolete code, includes SD_PREFER_LOCAL.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/5028F431.6000306@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

sched/numa: Add SD_PERFER_SIBLING to CPU domain

Commit 8e7fbcbc22c ("sched: Remove stale power aware scheduling remnants
and dysfunctional knobs") removed SD_PERFER_SIBLING from the CPU domain.

On NUMA machines this causes that load_balance() doesn't perfer LCPU in
same physical CPU package.

It causes some actual performance regressions on our NUMA machines from
Core2 to NHM and SNB.

Adding this domain flag again recovers the performance drop.

This change doesn't have any bad impact on any of my benchmarks:
specjbb, kbuild, fio, hackbench .. etc, on all my machines.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1342765190-21540-1-git-send-email-alex.shi@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched: Remove stale power aware scheduling remnants and dysfunctional knobs

It's been broken forever (i.e. it's not scheduling in a power
aware fashion), as reported by Suresh and others sending
patches, and nobody cares enough to fix it properly ...
so remove it to make space free for something better.

There's various problems with the code as it stands today, first
and foremost the user interface which is bound to topology
levels and has multiple values per level. This results in a
state explosion which the administrator or distro needs to
master and almost nobody does.

Furthermore large configuration state spaces aren't good, it
means the thing doesn't just work right because it's either
under so many impossibe to meet constraints, or even if
there's an achievable state workloads have to be aware of
it precisely and can never meet it for dynamic workloads.

So pushing this kind of decision to user-space was a bad idea
even with a single knob - it's exponentially worse with knobs
on every node of the topology.

There is a proposal to replace the user interface with a single
3 state knob:

sched_balance_policy := { performance, power, auto }

where 'auto' would be the preferred default which looks at things
like Battery/AC mode and possible cpufreq state or whatever the hw
exposes to show us power use expectations - but there's been no
progress on it in the past many months.

Aside from that, the actual implementation of the various knobs
is known to be broken. There have been sporadic attempts at
fixing things but these always stop short of reaching a mergable
state.

Therefore this wholesale removal with the hopes of spurring
people who care to come forward once again and work on a
coherent replacement.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1326104915.2442.53.camel@twins
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86: replace percpu_xxx funcs with this_cpu_xxx

Since percpu_xxx() serial functions are duplicated with this_cpu_xxx().
Removing percpu_xxx() definition and replacing them by this_cpu_xxx()
in code. There is no function change in this patch, just preparation for
later percpu_xxx serial function removing.

On x86 machine the this_cpu_xxx() serial functions are same as
__this_cpu_xxx() without no unnecessary premmpt enable/disable.

Thanks for Stephen Rothwell, he found and fixed a i386 build error in
the patch.

Also thanks for Andrew Morton, he kept updating the patchset in Linus'
tree.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

sched/numa: Rewrite the CONFIG_NUMA sched domain support

The current code groups up to 16 nodes in a level and then puts an
ALLNODES domain spanning the entire tree on top of that. This doesn't
reflect the numa topology and esp for the smaller not-fully-connected
machines out there today this might make a difference.

Therefore, build a proper numa topology based on node_distance().

Since there's no fixed numa layers anymore, the static SD_NODE_INIT
and SD_ALLNODES_INIT aren't usable anymore, the new code tries to
construct something similar and scales some values either on the
number of cpus in the domain and/or the node_distance() ratio.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Anton Blanchard <anton@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: linux-alpha@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: Matt Turner <mattst88@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: sparclinux@vger.kernel.org
Cc: Tony Luck <tony.luck@intel.com>
Cc: x86@kernel.org
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Greg Pearson <greg.pearson@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: bob.picco@oracle.com
Cc: chris.mason@oracle.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-r74n3n8hhuc2ynbrnp3vt954@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

sched: Allow SD_NODES_PER_DOMAIN to be overridden

We want to override the default value of SD_NODES_PER_DOMAIN on ppc64,
so move it into linux/topology.h.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

mm: increase RECLAIM_DISTANCE to 30

Recently, Robert Mueller reported (http://lkml.org/lkml/2010/9/12/236)
that zone_reclaim_mode doesn't work properly on his new NUMA server (Dual
Xeon E5520 + Intel S5520UR MB). He is using Cyrus IMAPd and it's built on
a very traditional single-process model.

* a master process which reads config files and manages the other
process
* multiple imapd processes, one per connection
* multiple pop3d processes, one per connection
* multiple lmtpd processes, one per connection
* periodical "cleanup" processes.

There are thousands of independent processes. The problem is, recent
Intel motherboard turn on zone_reclaim_mode by default and traditional
prefork model software don't work well on it. Unfortunatelly, such models
are still typical even in the 21st century. We can't ignore them.

This patch raises the zone_reclaim_mode threshold to 30. 30 doesn't have
any specific meaning. but 20 means that one-hop QPI/Hypertransport and
such relatively cheap 2-4 socket machine are often used for traditional
servers as above. The intention is that these machines don't use
zone_reclaim_mode.

Note: ia64 and Power have arch specific RECLAIM_DISTANCE definitions.
This patch doesn't change such high-end NUMA machine behavior.

Dave Hansen said:

: I know specifically of pieces of x86 hardware that set the information
: in the BIOS to '21' *specifically* so they'll get the zone_reclaim_mode
: behavior which that implies.
:
: They've done performance testing and run very large and scary benchmarks
: to make sure that they _want_ this turned on. What this means for them
: is that they'll probably be de-optimized, at least on newer versions of
: the kernel.
:
: If you want to do this for particular systems, maybe _that_'s what we
: should do. Have a list of specific configurations that need the
: defaults overridden either because they're buggy, or they have an
: unusual hardware configuration not really reflected in the distance
: table.

And later said:

: The original change in the hardware tables was for the benefit of a
: benchmark. Said benchmark isn't going to get run on mainline until the
: next batch of enterprise distros drops, at which point the hardware where
: this was done will be irrelevant for the benchmark. I'm sure any new
: hardware will just set this distance to another yet arbitrary value to
: make the kernel do what it wants. :)
:
: Also, when the hardware got _set_ to this initially, I complained. So, I
: guess I'm getting my way now, with this patch. I'm cool with it.

Reported-by: Robert Mueller <robm@fastmail.fm>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched: Add book scheduling domain

On top of the SMT and MC scheduling domains this adds the BOOK scheduling
domain. This is useful for NUMA like machines which do not have an interface
which tells which piece of memory is attached to which node or where the
hardware performs striping.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100831082844.253053798@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

topology: alternate fix for ia64 tiger_defconfig build breakage

Define stubs for the numa_*_id() generic percpu related functions for
non-NUMA configurations in <asm-generic/topology.h> where the other
non-numa stubs live.

Fixes ia64 !NUMA build breakage -- e.g., tiger_defconfig

Back out now unneeded '#ifndef CONFIG_NUMA' guards from ia64 smpboot.c

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched: Fix spelling of sibling

No logic changes, only spelling.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: linuxppc-dev@ozlabs.org
Cc: David Howells <dhowells@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <15249.1277776921@neuling.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Add asymmetric group packing option for sibling domain

Check to see if the group is packed in a sched doman.

This is primarily intended to used at the sibling level. Some cores
like POWER7 prefer to use lower numbered SMT threads. In the case of
POWER7, it can move to lower SMT modes only when higher threads are
idle. When in lower SMT modes, the threads will perform better since
they share less core resources. Hence when we have idle threads, we
want them to be the higher ones.

This adds a hook into f_b_g() called check_asym_packing() to check the
packing. This packing function is run on idle threads. It checks to
see if the busiest CPU in this domain (core in the P7 case) has a
higher CPU number than what where the packing function is being run
on. If it is, calculate the imbalance and return the higher busier
thread as the busiest group to f_b_g(). Here we are assuming a lower
CPU number will be equivalent to a lower SMT thread number.

It also creates a new SD_ASYM_PACKING flag to enable this feature at
any scheduler domain level.

It also creates an arch hook to enable this feature at the sibling
level. The default function doesn't enable this feature.

Based heavily on patch from Peter Zijlstra.
Fixes from Srivatsa Vaddagiri.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <20100608045702.2936CCC897@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

numa: introduce numa_mem_id()- effective local memory node id

Introduce numa_mem_id(), based on generic percpu variable infrastructure
to track "nearest node with memory" for archs that support memoryless
nodes.

Define API in <linux/topology.h> when CONFIG_HAVE_MEMORYLESS_NODES
defined, else stubs. Architectures will define HAVE_MEMORYLESS_NODES
if/when they support them.

Archs can override definitions of:

numa_mem_id() - returns node number of "local memory" node
set_numa_mem() - initialize [this cpus'] per cpu variable 'numa_mem'
cpu_to_mem() - return numa_mem for specified cpu; may be used as lvalue

Generic initialization of 'numa_mem' occurs in __build_all_zonelists().
This will initialize the boot cpu at boot time, and all cpus on change of
numa_zonelist_order, or when node or memory hot-plug requires zonelist
rebuild. Archs that support memoryless nodes will need to initialize
'numa_mem' for secondary cpus as they're brought on-line.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

numa: add generic percpu var numa_node_id() implementation

Rework the generic version of the numa_node_id() function to use the new
generic percpu variable infrastructure.

Guard the new implementation with a new config option:

CONFIG_USE_PERCPU_NUMA_NODE_ID.

Archs which support this new implemention will default this option to 'y'
when NUMA is configured. This config option could be removed if/when all
archs switch over to the generic percpu implementation of numa_node_id().
Arch support involves:

1) converting any existing per cpu variable implementations to use
this implementation. x86_64 is an instance of such an arch.
2) archs that don't use a per cpu variable for numa_node_id() will
need to initialize the new per cpu variable "numa_node" as cpus
are brought on-line. ia64 is an example.
3) Defining USE_PERCPU_NUMA_NODE_ID in arch dependent Kconfig--e.g.,
when NUMA is configured. This is required because I have
retained the old implementation by default to allow archs to
be modified incrementally, as desired.

Subsequent patches will convert x86_64 and ia64 to use this implemenation.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched: Fix vmark regression on big machines

SD_PREFER_SIBLING is set at the CPU domain level if power saving isn't
enabled, leading to many cache misses on large machines as we traverse
looking for an idle shared cache to wake to. Change the enabler of
select_idle_sibling() to SD_SHARE_PKG_RESOURCES, and enable same at the
sibling domain level.

Reported-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1262612696.15495.15.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Disable SD_PREFER_LOCAL for MC/CPU domains

Yanmin reported that both tbench and hackbench were significantly
hurt by trying to keep tasks local on these domains, esp on small
cache machines.

So disable it in order to promote spreading outside of the cache
domains.

Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1255083400.8802.15.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

cpumask: remove obsolete topology_core_siblings and topology_thread_siblings: core

There were replaced by topology_core_cpumask and topology_thread_cpumask.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

sched: Disable wakeup balancing

Sysbench thinks SD_BALANCE_WAKE is too agressive and kbuild doesn't
really mind too much, SD_BALANCE_NEWIDLE picks up most of the
slack.

On a dual socket, quad core, dual thread nehalem system:

sysbench (--num_threads=16):

SD_BALANCE_WAKE-: 13982 tx/s
SD_BALANCE_WAKE+: 15688 tx/s

kbuild (-j16):

SD_BALANCE_WAKE-: 47.648295846 seconds time elapsed ( +- 0.312% )
SD_BALANCE_WAKE+: 47.608607360 seconds time elapsed ( +- 0.026% )

(same within noise)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Add SD_PREFER_LOCAL

And turn it on for NUMA and MC domains. This improves
locality in balancing decisions by keeping up to
capacity amount of tasks local before looking for idle
CPUs. (and twice the capacity if SD_POWERSAVINGS_BALANCE
is set.)

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Reduce forkexec_idx

If we're looking to place a new task, we might as well find the
idlest position _now_, not 1 tick ago.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Improve latencies and throughput

Make the idle balancer more agressive, to improve a
x264 encoding workload provided by Jason Garrett-Glaser:

NEXT_BUDDY NO_LB_BIAS
encoded 600 frames, 252.82 fps, 22096.60 kb/s
encoded 600 frames, 250.69 fps, 22096.60 kb/s
encoded 600 frames, 245.76 fps, 22096.60 kb/s

NO_NEXT_BUDDY LB_BIAS
encoded 600 frames, 344.44 fps, 22096.60 kb/s
encoded 600 frames, 346.66 fps, 22096.60 kb/s
encoded 600 frames, 352.59 fps, 22096.60 kb/s

NO_NEXT_BUDDY NO_LB_BIAS
encoded 600 frames, 425.75 fps, 22096.60 kb/s
encoded 600 frames, 425.45 fps, 22096.60 kb/s
encoded 600 frames, 422.49 fps, 22096.60 kb/s

Peter pointed out that this is better done via newidle_idx,
not via LB_BIAS, newidle balancing should look for where
there is load _now_, not where there was load 2 ticks ago.

Worst-case latencies are improved as well as no buddies
means less vruntime spread. (as per prior lkml discussions)

This change improves kbuild-peak parallelism as well.

Reported-by: Jason Garrett-Glaser <darkshikari@gmail.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1253011667.9128.16.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Fix some domain tunings

CPU level should have WAKE_AFFINE, whereas ALLNODES is dubious.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Tweak wake_idx

When merging select_task_rq_fair() and sched_balance_self() we lost
the use of wake_idx, restore that and set them to 0 to make wake
balancing more aggressive.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Merge select_task_rq_fair() and sched_balance_self()

The problem with wake_idle() is that is doesn't respect things like
cpu_power, which means it doesn't deal well with SMT nor the recent
RT interaction.

To cure this, it needs to do what sched_balance_self() does, which
leads to the possibility of merging select_task_rq_fair() and
sched_balance_self().

Modify sched_balance_self() to:

- update_shares() when walking up the domain tree,
(it only called it for the top domain, but it should
have done this anyway), which allows us to remove
this ugly bit from try_to_wake_up().

- do wake_affine() on the smallest domain that contains
both this (the waking) and the prev (the wakee) cpu for
WAKE invocations.

Then use the top-down balance steps it had to replace wake_idle().

This leads to the dissapearance of SD_WAKE_BALANCE and
SD_WAKE_IDLE_FAR, with SD_WAKE_IDLE replaced with SD_BALANCE_WAKE.

SD_WAKE_AFFINE needs SD_BALANCE_WAKE to be effective.

Touch all topology bits to replace the old with new SD flags --
platforms might need re-tuning, enabling SD_BALANCE_WAKE
conditionally on a NUMA distance seems like a good additional
feature, magny-core and small nehalem systems would want this
enabled, systems with slow interconnects would not.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: enable SD_WAKE_IDLE

Now that SD_WAKE_IDLE doesn't make pipe-test suck anymore,
enable it by default for MC, CPU and NUMA domains.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Turn on SD_BALANCE_NEWIDLE

Start the re-tuning of the balancer by turning on newidle.

It improves hackbench performance and parallelism on a 4x4 box.
The "perf stat --repeat 10" measurements give us:

domain0 domain1
.......................................
-SD_BALANCE_NEWIDLE -SD_BALANCE_NEWIDLE:
2041.273208 task-clock-msecs # 9.354 CPUs ( +- 0.363% )

+SD_BALANCE_NEWIDLE -SD_BALANCE_NEWIDLE:
2086.326925 task-clock-msecs # 11.934 CPUs ( +- 0.301% )

+SD_BALANCE_NEWIDLE +SD_BALANCE_NEWIDLE:
2115.289791 task-clock-msecs # 12.158 CPUs ( +- 0.263% )

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Clean up topology.h

Re-organize the flag settings so that it's visible at a glance
which sched-domains flags are set and which not.

With the new balancer code we'll need to re-tune these details
anyway, so make it cleaner to make fewer mistakes down the
road ;-)

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: Add smt_gain

The idea is that multi-threading a core yields more work
capacity than a single thread, provide a way to express a
static gain for threads.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: Gautham R Shenoy <ego@in.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
LKML-Reference: <20090901083826.073345955@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

numa, cpumask: move numa_node_id default implementation to topology.h

Impact: cleanup, potential bugfix

Not sure what changed to expose this, but clearly that numa_node_id()
doesn't belong in mmzone.h (the inline in gfp.h is probably overkill, too).

In file included from include/linux/topology.h:34,
from arch/x86/mm/numa.c:2:
/home/rusty/patches-cpumask/linux-2.6/arch/x86/include/asm/topology.h:64:1: warning: "numa_node_id" redefined
In file included from include/linux/topology.h:32,
from arch/x86/mm/numa.c:2:
include/linux/mmzone.h:770:1: warning: this is the location of the previous definition

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Mike Travis <travis@sgi.com>
LKML-Reference: <200903132343.37661.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

cpumask: replace node_to_cpumask with cpumask_of_node.

Impact: cleanup

node_to_cpumask (and the blecherous node_to_cpumask_ptr which
contained a declaration) are replaced now everyone implements
cpumask_of_node.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

cpumask: Use topology_core_cpumask()/topology_thread_cpumask()

Impact: reduce stack usage, use new cpumask API.

This actually uses topology_core_cpumask() and
topology_thread_cpumask(), removing the only users of
topology_core_siblings() and topology_thread_siblings()

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: linux-net-drivers@solarflare.com

sched: add SD_BALANCE_NEWIDLE at MC and CPU level for sched_mc>0

Impact: change task balancing to save power more agressively

Add SD_BALANCE_NEWIDLE flag at MC level and CPU level
if sched_mc is set. This helps power savings and
will not affect performance when sched_mc=0

Ingo and Mike Galbraith have optimised the SD flags by
removing SD_BALANCE_NEWIDLE at MC and CPU level. This
helps performance but hurts power savings since this
slows down task consolidation by reducing the number
of times load_balance is run.

sched: fine-tune SD_MC_INIT
commit 14800984706bf6936bbec5187f736e928be5c218
Author: Mike Galbraith <efault@gmx.de>
Date: Fri Nov 7 15:26:50 2008 +0100

sched: re-tune balancing -- revert
commit 9fcd18c9e63e325dbd2b4c726623f760788d5aa8
Author: Ingo Molnar <mingo@elte.hu>
Date: Wed Nov 5 16:52:08 2008 +0100

This patch selectively enables SD_BALANCE_NEWIDLE flag
only when sched_mc is set to 1 or 2. This helps power savings
by task consolidation and also does not hurt performance at
sched_mc=0 where all power saving optimisations are turned off.

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: convert BALANCE_FOR_xx_POWER to inline functions

Impact: cleanup

BALANCE_FOR_MC_POWER and similar macros defined in sched.h are
not constants and have various condition checks and significant
amount of code that is not suitable to be contain in a macro.
Also there could be side effects on the expressions passed to
some of them like test_sd_parent().

This patch converts all complex macros related to power savings
balance to inline functions.

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: let arch_update_cpu_topology indicate if topology changed

Change arch_update_cpu_topology so it returns 1 if the cpu topology changed
and 0 if it didn't change. This will be useful for the next patch which adds
a call to this function in partition_sched_domains.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: fine-tune SD_SIBLING_INIT

fine-tune the HT sched-domains parameters as well.

On a HT capable box, this increases lat_ctx performance from 23.87
usecs to 1.49 usecs:

# before

$ ./lat_ctx -s 0 2

"size=0k ovr=1.89
2 23.87

# after

$ ./lat_ctx -s 0 2

"size=0k ovr=1.84
2 1.49

Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: fine-tune SD_MC_INIT

Tune SD_MC_INIT the same way as SD_CPU_INIT:
unset SD_BALANCE_NEWIDLE, and set SD_WAKE_BALANCE.

This improves vmark by 5%:

vmark 132102 125968 125497 messages/sec avg 127855.66 .984
vmark 139404 131719 131272 messages/sec avg 134131.66 1.033

Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

# *DOCUMENTATION*

sched: re-tune balancing

Impact: improve wakeup affinity on NUMA systems, tweak SMP systems

Given the fixes+tweaks to the wakeup-buddy code, re-tweak the domain
balancing defaults on NUMA and SMP systems.

Turn on SD_WAKE_AFFINE which was off on x86 NUMA - there's no reason
why we would not want to have wakeup affinity across nodes as well.
(we already do this in the standard NUMA template.)

lat_ctx on a NUMA box is particularly happy about this change:

before:

| phoenix:~/l> ./lat_ctx -s 0 2
| "size=0k ovr=2.60
| 2 5.70

after:

| phoenix:~/l> ./lat_ctx -s 0 2
| "size=0k ovr=2.65
| 2 2.07

a 2.75x speedup.

pipe-test is similarly happy about it too:

| phoenix:~/sched-tests> ./pipe-test
| 18.26 usecs/loop.
| 14.70 usecs/loop.
| 14.38 usecs/loop.
| 10.55 usecs/loop. # +WAKE_AFFINE on domain0+domain1
| 8.63 usecs/loop.
| 8.59 usecs/loop.
| 9.03 usecs/loop.
| 8.94 usecs/loop.
| 8.96 usecs/loop.
| 8.63 usecs/loop.

Also:

- disable SD_BALANCE_NEWIDLE on NUMA and SMP domains (keep it for siblings)
- enable SD_WAKE_BALANCE on SMP domains

Sysbench+postgresql improves all around the board, quite significantly:

.28-rc3-11474e2c .28-rc3-11474e2c-tune
-------------------------------------------------
1: 571 688 +17.08%
2: 1236 1206 -2.55%
4: 2381 2642 +9.89%
8: 4958 5164 +3.99%
16: 9580 9574 -0.07%
32: 7128 8118 +12.20%
64: 7342 8266 +11.18%
128: 7342 8064 +8.95%
256: 7519 7884 +4.62%
512: 7350 7731 +4.93%
-------------------------------------------------
SUM: 55412 59341 +6.62%

So it's a win both for the runup portion, the peak area and the tail.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

cpu topology: always define CPU topology information

This can result in an empty topology directory in sysfs, and requires
in-kernel users to protect all uses with #ifdef - see
<http://marc.info/?l=linux-netdev&m=120639033904472&w=2>.

The documentation of CPU topology specifies what the defaults should be if
only partial information is available from the hardware. So we can
provide these defaults as a fallback.

This patch:

- Adds default definitions of the 4 topology macros to <linux/topology.h>
- Changes drivers/base/topology.c to use the topology macros unconditionally
and to cope with definitions that aren't lvalues
- Updates documentation accordingly

[ From: Andrew Morton <akpm@linux-foundation.org>
- fold now-duplicated code
- fix layout
]

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Chandra Seetharaman <sekharan@us.ibm.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Mike Travis <travis@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: John Hawkes <hawkes@sgi.com>
Cc: Zhang, Yanmin <yanmin.zhang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: re-tune NUMA topologies

improve the sysbench ramp-up phase and its peak throughput on
a 16way NUMA box, by turning on WAKE_AFFINE:

tip/sched tip/sched+wake-affine
-------------------------------------------------
1: 700 830 +15.65%
2: 1465 1391 -5.28%
4: 3017 3105 +2.81%
8: 5100 6021 +15.30%
16: 10725 10745 +0.19%
32: 10135 10150 +0.16%
64: 9338 9240 -1.06%
128: 8599 8252 -4.21%
256: 8475 8144 -4.07%
-------------------------------------------------
SUM: 57558 57882 +0.56%

this change also improves lat_ctx from 6.69 usecs to 1.11 usec:

$ ./lat_ctx -s 0 2
"size=0k ovr=1.19
2 1.11

$ ./lat_ctx -s 0 2
"size=0k ovr=1.22
2 6.69

in sysbench it's an overall win with some weakness at the lots-of-clients
side. That happens because we now under-balance this workload
a bit. To counter that effect, turn on NEWIDLE:

wake-idle wake-idle+newidle
-------------------------------------------------
1: 830 834 +0.43%
2: 1391 1401 +0.65%
4: 3105 3091 -0.43%
8: 6021 6046 +0.42%
16: 10745 10736 -0.08%
32: 10150 10206 +0.55%
64: 9240 9533 +3.08%
128: 8252 8355 +1.24%
256: 8144 8384 +2.87%
-------------------------------------------------
SUM: 57882 58591 +1.21%

as a bonus this not only improves the many-clients case but
also improves the (more important) rampup phase.

sysbench is a workload that quickly breaks down if the
scheduler over-balances, so since it showed an improvement
under NEWIDLE this change is definitely good.

cpumask: reduce stack usage in SD_x_INIT initializers

* Remove empty cpumask_t (and all non-zero/non-null) variables
in SD_*_INIT macros. Use memset(0) to clear. Also, don't
inline the initializer functions to save on stack space in
build_sched_domains().

* Merge change to include/linux/topology.h that uses the new
node_to_cpumask_ptr function in the nr_cpus_node macro into
this patch.

Depends on:
[mm-patch]: asm-generic-add-node_to_cpumask_ptr-macro.patch
[sched-devel]: sched: add new set_cpus_allowed_ptr function

Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: add arch_update_cpu_topology hook.

Will be called each time the scheduling domains are rebuild.
Needed for architectures that don't have a static cpu topology.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: tune multi-core idle balancing

WAKE_IDLE is too agressive on multi-core CPUs with the new
wake-affine code, keep it on for SMT/HT balancing alone
(where there's no cache affinity at all between logical CPUs).

Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: whitespace cleanups in topology.h

whitespace cleanups in topology.h.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: reactivate fork balancing

reactivate fork balancing.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: enable wake-idle on CONFIG_SCHED_MC=y

most multicore CPUs today have shared L2 caches, so tune things so
that the spreading amongst cores is more aggressive.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

sched: reintroduce topology.h tunings

reintroduce the 2.6.22 topology.h tunings again - they result in
slightly better balancing.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

[PATCH] sched: remove cache_hot_time

remove the last unused remains of cache_hot_time.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

[PATCH] sched: small topology.h cleanup

trivial cleanup: LOCAL_DISTANCE and REMOTE_DISTANCE are only used in
topology.h and inside an #ifndef section - limit their existence to
that #ifndef.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sched: more agressive idle balancing

the Linux scheduler is starving a number of workloads. So default
to more agressive idle-balancing. This hurts lmbench context-switching
numbers (which was the main reason we sucked at idle-balancing for
such a long time) but the lmbench numbers are fine once the system is
minimally utilized.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

[PATCH] sched: remove SMT nice

Remove the SMT-nice feature which idles sibling cpus on SMT cpus to
facilitiate nice working properly where cpu power is shared. The idling of
cpus in the presence of runnable tasks is considered too fragile, easy to
break with outside code, and the complexity of managing this system if an
architecture comes along with many logical cores sharing cpu power will be
unworkable.

Remove the associated per_cpu_gain variable in sched_domains used only by
this code.

Also:

The reason is that with dynticks enabled, this code breaks without yet
further tweaks so dynticks brought on the rapid demise of this code. So
either we tweak this code or kill it off entirely. It was Ingo's preference
to kill it off. Either way this needs to happen for 2.6.21 since dynticks
has gone in.

Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] sched: add option to serialize load balancing

Large sched domains can be very expensive to scan. Add an option SD_SERIALIZE
to the sched domain flags. If that flag is set then we make sure that no
other such domain is being balanced.

[akpm@osdl.org: build fix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] sched domain: increase the SMT busy rebalance interval

With SMT, if the logical processor is busy, load balance happens for every
8msec(min)-16msec(max). There is no need to do this often, as this is just
for fairness(to maintain uniform runqueue lengths) and default time slice
anyhow is 100msec.

Appended patch increases this interval to 64msec(min)-128msec(max) when the
logical processor is busy.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] sched: cleanup sched_group cpu_power setup

Up to now sched group's cpu_power for each sched domain is initialized
independently. This made the setup code ugly as the new sched domains are
getting added.

Make the sched group cpu_power setup code generic, by using domain child
field and new domain flag in sched_domain. For most of the sched
domains(except NUMA), sched group's cpu_power is now computed generically
using the domain properties of itself and of the child domain.

sched groups in NUMA domains are setup little differently and hence they
don't use this generic mechanism.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] sched: introduce child field in sched_domain

Introduce the child field in sched_domain struct and use it in
sched_balance_self().

We will also use this field in cleaning up the sched group cpu_power
setup(done in a different patch) code.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] sched: mc/smt power savings sched policy

sysfs entries 'sched_mc_power_savings' and 'sched_smt_power_savings' in
/sys/devices/system/cpu/ control the MC/SMT power savings policy for the
scheduler.

Based on the values (1-enable, 0-disable) for these controls, sched groups
cpu power will be determined for different domains. When power savings
policy is enabled and under light load conditions, scheduler will minimize
the physical packages/cpu cores carrying the load and thus conserving
power(with a perf impact based on the workload characteristics... see OLS
2005 CMP kernel scheduler paper for more details..)

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Con Kolivas <kernel@kolivas.org>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] sched: new sched domain for representing multi-core

Add a new sched domain for representing multi-core with shared caches
between cores. Consider a dual package system, each package containing two
cores and with last level cache shared between cores with in a package. If
there are two runnable processes, with this appended patch those two
processes will be scheduled on different packages.

On such systems, with this patch we have observed 8% perf improvement with
specJBB(2 warehouse) benchmark and 35% improvement with CFP2000 rate(with 2
users).

This new domain will come into play only on multi-core systems with shared
caches. On other systems, this sched domain will be removed by domain
degeneration code. This new domain can be also used for implementing power
savings policy (see OLS 2005 CMP kernel scheduler paper for more details..
I will post another patch for power savings policy soon)

Most of the arch/* file changes are for cpu_coregroup_map() implementation.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] Zone reclaim: Reclaim logic

Some bits for zone reclaim exists in 2.6.15 but they are not usable. This
patch fixes them up, removes unused code and makes zone reclaim usable.

Zone reclaim allows the reclaiming of pages from a zone if the number of
free pages falls below the watermarks even if other zones still have enough
pages available. Zone reclaim is of particular importance for NUMA
machines. It can be more beneficial to reclaim a page than taking the
performance penalties that come with allocating a page on a remote zone.

Zone reclaim is enabled if the maximum distance to another node is higher
than RECLAIM_DISTANCE, which may be defined by an arch. By default
RECLAIM_DISTANCE is 20. 20 is the distance to another node in the same
component (enclosure or motherboard) on IA64. The meaning of the NUMA
distance information seems to vary by arch.

If zone reclaim is not successful then no further reclaim attempts will
occur for a certain time period (ZONE_RECLAIM_INTERVAL).

This patch was discussed before. See

http://marc.theaimsgroup.com/?l=linux-kernel&m=113519961504207&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=113408418232531&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=113389027420032&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=113380938612205&w=2

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] scheduler cache-hot-autodetect


From: Ingo Molnar <mingo@elte.hu>

This is the latest version of the scheduler cache-hot-auto-tune patch.

The first problem was that detection time scaled with O(N^2), which is
unacceptable on larger SMP and NUMA systems. To solve this:

- I've added a 'domain distance' function, which is used to cache
measurement results. Each distance is only measured once. This means
that e.g. on NUMA distances of 0, 1 and 2 might be measured, on HT
distances 0 and 1, and on SMP distance 0 is measured. The code walks
the domain tree to determine the distance, so it automatically follows
whatever hierarchy an architecture sets up. This cuts down on the boot
time significantly and removes the O(N^2) limit. The only assumption
is that migration costs can be expressed as a function of domain
distance - this covers the overwhelming majority of existing systems,
and is a good guess even for more assymetric systems.

[ People hacking systems that have assymetries that break this
assumption (e.g. different CPU speeds) should experiment a bit with
the cpu_distance() function. Adding a ->migration_distance factor to
the domain structure would be one possible solution - but lets first
see the problem systems, if they exist at all. Lets not overdesign. ]

Another problem was that only a single cache-size was used for measuring
the cost of migration, and most architectures didnt set that variable
up. Furthermore, a single cache-size does not fit NUMA hierarchies with
L3 caches and does not fit HT setups, where different CPUs will often
have different 'effective cache sizes'. To solve this problem:

- Instead of relying on a single cache-size provided by the platform and
sticking to it, the code now auto-detects the 'effective migration
cost' between two measured CPUs, via iterating through a wide range of
cachesizes. The code searches for the maximum migration cost, which
occurs when the working set of the test-workload falls just below the
'effective cache size'. I.e. real-life optimized search is done for
the maximum migration cost, between two real CPUs.

This, amongst other things, has the positive effect hat if e.g. two
CPUs share a L2/L3 cache, a different (and accurate) migration cost
will be found than between two CPUs on the same system that dont share
any caches.

(The reliable measurement of migration costs is tricky - see the source
for details.)

Furthermore i've added various boot-time options to override/tune
migration behavior.

Firstly, there's a blanket override for autodetection:

migration_cost=1000,2000,3000

will override the depth 0/1/2 values with 1msec/2msec/3msec values.

Secondly, there's a global factor that can be used to increase (or
decrease) the autodetected values:

migration_factor=120

will increase the autodetected values by 20%. This option is useful to
tune things in a workload-dependent way - e.g. if a workload is
cache-insensitive then CPU utilization can be maximized by specifying
migration_factor=0.

I've tested the autodetection code quite extensively on x86, on 3
P3/Xeon/2MB, and the autodetected values look pretty good:

Dual Celeron (128K L2 cache):

---------------------
migration cost matrix (max_cache_size: 131072, cpu: 467 MHz):
---------------------
[00] [01]
[00]: - 1.7(1)
[01]: 1.7(1) -
---------------------
cacheflush times [2]: 0.0 (0) 1.7 (1784008)
---------------------

Here the slow memory subsystem dominates system performance, and even
though caches are small, the migration cost is 1.7 msecs.

Dual HT P4 (512K L2 cache):

---------------------
migration cost matrix (max_cache_size: 524288, cpu: 2379 MHz):
---------------------
[00] [01] [02] [03]
[00]: - 0.4(1) 0.0(0) 0.4(1)
[01]: 0.4(1) - 0.4(1) 0.0(0)
[02]: 0.0(0) 0.4(1) - 0.4(1)
[03]: 0.4(1) 0.0(0) 0.4(1) -
---------------------
cacheflush times [2]: 0.0 (33900) 0.4 (448514)
---------------------

Here it can be seen that there is no migration cost between two HT
siblings (CPU#0/2 and CPU#1/3 are separate physical CPUs). A fast memory
system makes inter-physical-CPU migration pretty cheap: 0.4 msecs.

8-way P3/Xeon [2MB L2 cache]:

---------------------
migration cost matrix (max_cache_size: 2097152, cpu: 700 MHz):
---------------------
[00] [01] [02] [03] [04] [05] [06] [07]
[00]: - 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1)
[01]: 19.2(1) - 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1)
[02]: 19.2(1) 19.2(1) - 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1)
[03]: 19.2(1) 19.2(1) 19.2(1) - 19.2(1) 19.2(1) 19.2(1) 19.2(1)
[04]: 19.2(1) 19.2(1) 19.2(1) 19.2(1) - 19.2(1) 19.2(1) 19.2(1)
[05]: 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1) - 19.2(1) 19.2(1)
[06]: 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1) - 19.2(1)
[07]: 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1) 19.2(1) -
---------------------
cacheflush times [2]: 0.0 (0) 19.2 (19281756)
---------------------

This one has huge caches and a relatively slow memory subsystem - so the
migration cost is 19 msecs.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Cc: <wilder@us.ibm.com>
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] cpusets: Move the ia64 domain setup code to the generic code

Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] sched: sched tuning

Do some basic initial tuning.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] sched: balance on fork

Reimplement the balance on exec balancing to be sched-domains aware. Use this
to also do balance on fork balancing. Make x86_64 do balance on fork over the
NUMA domain.

The problem that the non sched domains aware blancing became apparent on dual
core, multi socket opterons. What we want is for the new tasks to be sent to
a different socket, but more often than not, we would first load up our
sibling core, or fill two cores of a single remote socket before selecting a
new one.

This gives large improvements to STREAM on such systems.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] sched: no aggressive idle balancing

Remove the very aggressive idle stuff that has recently gone into 2.6 - it is
going against the direction we are trying to go. Hopefully we can regain
performance through other methods.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] sched: balance timers

Do CPU load averaging over a number of different intervals. Allow each
interval to be chosen by sending a parameter to source_load and target_load.
0 is instantaneous, idx > 0 returns a decaying average with the most recent
sample weighted at 2^(idx-1). To a maximum of 3 (could be easily increased).

So generally a higher number will result in more conservative balancing.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!