History log of /freebsd-10.3-release/sys/kern/subr_pcpu.c
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# 296373 04-Mar-2016 marius

- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

# 262739 04-Mar-2014 glebius

Merge r261722, r261723, r261724, r261725 from head:
several minor improvements for UMA_ZPCPU_ZONE zones.


# 256281 10-Oct-2013 gjb

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation


# 227293 07-Nov-2011 ed

Mark MALLOC_DEFINEs static that have no corresponding MALLOC_DECLAREs.

This means that their use is restricted to a single C file.


# 224218 19-Jul-2011 attilio

Remove pc_name member of struct pcpu.
pc_name is only included when KTR option is and it does introduce a
subdle KBI breakage that totally breaks vmstat when world and kernel are
not in sync.
Besides, it is not used somewhere.

In collabouration with: pluknet
Reviewed by: jhb
Approved by: re (kib)


# 223758 04-Jul-2011 attilio

With retirement of cpumask_t and usage of cpuset_t for representing a
mask of CPUs, pc_other_cpus and pc_cpumask become highly inefficient.

Remove them and replace their usage with custom pc_cpuid magic (as,
atm, pc_cpumask can be easilly represented by (1 << pc_cpuid) and
pc_other_cpus by (all_cpus & ~(1 << pc_cpuid))).

This change is not targeted for MFC because of struct pcpu members
removal and dependency by cpumask_t retirement.

MD review by: marcel, marius, alc
Tested by: pluknet
MD testing by: marcel, marius, gonzo, andreast


# 222813 07-Jun-2011 attilio

etire the cpumask_t type and replace it with cpuset_t usage.

This is intended to fix the bug where cpu mask objects are
capped to 32. MAXCPU, then, can now arbitrarely bumped to whatever
value. Anyway, as long as several structures in the kernel are
statically allocated and sized as MAXCPU, it is suggested to keep it
as low as possible for the time being.

Technical notes on this commit itself:
- More functions to handle with cpuset_t objects are introduced.
The most notable are cpusetobj_ffs() (which calculates a ffs(3)
for a cpuset_t object), cpusetobj_strprint() (which prepares a string
representing a cpuset_t object) and cpusetobj_strscan() (which
creates a valid cpuset_t starting from a string representation).
- pc_cpumask and pc_other_cpus are target to be removed soon.
With the moving from cpumask_t to cpuset_t they are now inefficient
and not really useful. Anyway, for the time being, please note that
access to pcpu datas is protected by sched_pin() in order to avoid
migrating the CPU while reading more than one (possible) word
- Please note that size of cpuset_t objects may differ between kernel
and userland. While this is not directly related to the patch itself,
it is good to understand that concept and possibly use the patch
as a reference on how to deal with cpuset_t objects in userland, when
accessing kernland members.
- KTR_CPUMASK is changed and now is represented through a string, to be
set as the example reported in NOTES.

Please additively note that no MAXCPU is bumped in this patch, but
private testing has been done until to MAXCPU=128 on a real 8x8x2(htt)
machine (amd64).

Please note that the FreeBSD version is not yet bumped because of
the upcoming pcpu changes. However, note that this patch is not
targeted for MFC.

People to thank for the time spent on this patch:
- sbruno, pluknet and Nicholas Esborn (nick AT desert DOT net) tested
several revision of the patches and really helped in improving
stability of this work.
- marius fixed several bugs in the sparc64 implementation and reviewed
patches related to ktr.
- jeff and jhb discussed the basic approach followed.
- kib and marcel made targeted review on some specific part of the
patch.
- marius, art, nwhitehorn and andreast reviewed MD specific part of
the patch.
- marius, andreast, gonzo, nwhitehorn and jceel tested MD specific
implementations of the patch.
- Other people have made contributions on other patches that have been
already committed and have been listed separately.

Companies that should be mentioned for having participated at several
degrees:
- Yahoo! for having offered the machines used for testing on big
count of CPUs.
- The FreeBSD Foundation for having sponsored my devsummit attendance,
which has been instrumental.
- Sandvine for having offered offices and infrastructure during
development.

(I really hope I didn't forget anyone, if it happened I apologize in
advance).


# 222531 31-May-2011 nwhitehorn

On multi-core, multi-threaded PPC systems, it is important that the threads
be brought up in the order they are enumerated in the device tree (in
particular, that thread 0 on each core be brought up first). The SLIST
through which we loop to start the CPUs has all of its entries added with
SLIST_INSERT_HEAD(), which means it is in reverse order of enumeration
and so AP startup would always fail in such situations (causing a machine
check or RTAS failure). Fix this by changing the SLIST into an STAILQ,
and inserting new CPUs at the end.

Reviewed by: jhb


# 217265 11-Jan-2011 jhb

Remove unneeded includes of <sys/linker_set.h>. Other headers that use
it internally contain nested includes.

Reviewed by: bde


# 215701 22-Nov-2010 dim

After some off-list discussion, revert a number of changes to the
DPCPU_DEFINE and VNET_DEFINE macros, as these cause problems for various
people working on the affected files. A better long-term solution is
still being considered. This reversal may give some modules empty
set_pcpu or set_vnet sections, but these are harmless.

Changes reverted:

------------------------------------------------------------------------
r215318 | dim | 2010-11-14 21:40:55 +0100 (Sun, 14 Nov 2010) | 4 lines

Instead of unconditionally emitting .globl's for the __start_set_xxx and
__stop_set_xxx symbols, only emit them when the set_vnet or set_pcpu
sections are actually defined.

------------------------------------------------------------------------
r215317 | dim | 2010-11-14 21:38:11 +0100 (Sun, 14 Nov 2010) | 3 lines

Apply the STATIC_VNET_DEFINE and STATIC_DPCPU_DEFINE macros throughout
the tree.

------------------------------------------------------------------------
r215316 | dim | 2010-11-14 21:23:02 +0100 (Sun, 14 Nov 2010) | 2 lines

Add macros to define static instances of VNET_DEFINE and DPCPU_DEFINE.


# 215317 14-Nov-2010 dim

Apply the STATIC_VNET_DEFINE and STATIC_DPCPU_DEFINE macros throughout
the tree.


# 209059 11-Jun-2010 jhb

Update several places that iterate over CPUs to use CPU_FOREACH().


# 208392 21-May-2010 jhb

- Adjust the whitespace for the lines that output fields in 'show pcpu' in
DDB so that all the fields line up.
- Print out the tid of the per-CPU idlethread instead of the pid since
the idle process is now shared across all idle threads.

MFC after: 1 month


# 208100 14-May-2010 bz

Fix an issue with the dynamic pcpu/vnet data allocators.

We cannot expect that modspace is the last entry in the linker
set and thus that modspace + possible extra space up to PAGE_SIZE
would be contiguous. For the moment do not support more than
*_MODMIN space and ignore the extra space (*).

(*) We know how to get it back but it'll need testing.

Discussed with: jeff, rwatson (briefly)
Reviewed by: jeff
Sponsored by: The FreeBSD Foundation
Sponsored by: CK Software GmbH
MFC after: 4 days


# 207929 11-May-2010 attilio

Right now, WITNESS just blindly pipes all the output to the
(TOCONS | TOLOG) mask even when called from DDB points.
That breaks several output, where the most notable is textdump output.
Fix this by having configurable callbacks passed to witness_list_locks()
and witness_display_spinlock() for printing out datas.

Reported by: several broken textdump outputs
Tested by: Giovanni Trematerra
<giovanni dot trematerra at gmail dot com>
MFC after: 7 days
X-MFC: r207922


# 196132 12-Aug-2009 bz

Add ddb show dpcpu_off command to ease dpcpu memory debugging.
While show pcpu prints pc_dynamic this also prints the original
memory address as well as the maths.

Once dpcpu goes NUMA this is considered to help debugging as well.

Reviewed by: rwatson
Approved by: re


# 194935 25-Jun-2009 jeff

- Add a sysctl_dpcpu_long to support long typed pcpu stats.
- Remove the #ifndef SMP case as the SMP code works on UP as well.

Reviewed by: sam


# 194784 23-Jun-2009 jeff

Implement a facility for dynamic per-cpu variables.
- Modules and kernel code alike may use DPCPU_DEFINE(),
DPCPU_GET(), DPCPU_SET(), etc. akin to the statically defined
PCPU_*. Requires only one extra instruction more than PCPU_* and is
virtually the same as __thread for builtin and much faster for shared
objects. DPCPU variables can be initialized when defined.
- Modules are supported by relocating the module's per-cpu linker set
over space reserved in the kernel. Modules may fail to load if there
is insufficient space available.
- Track space available for modules with a one-off extent allocator.
Free may block for memory to allocate space for an extent.

Reviewed by: jhb, rwatson, kan, sam, grehan, marius, marcel, stas


# 191816 05-May-2009 zec

Change the curvnet variable from a global const struct vnet *,
previously always pointing to the default vnet context, to a
dynamically changing thread-local one. The currvnet context
should be set on entry to networking code via CURVNET_SET() macros,
and reverted to previous state via CURVNET_RESTORE(). Recursions
on curvnet are permitted, though strongly discuouraged.

This change should have no functional impact on nooptions VIMAGE
kernel builds, where CURVNET_* macros expand to whitespace.

The curthread->td_vnet (aka curvnet) variable's purpose is to be an
indicator of the vnet context in which the current network-related
operation takes place, in case we cannot deduce the current vnet
context from any other source, such as by looking at mbuf's
m->m_pkthdr.rcvif->if_vnet, sockets's so->so_vnet etc. Moreover, so
far curvnet has turned out to be an invaluable consistency checking
aid: it helps to catch cases when sockets, ifnets or any other
vnet-aware structures may have leaked from one vnet to another.

The exact placement of the CURVNET_SET() / CURVNET_RESTORE() macros
was a result of an empirical iterative process, whith an aim to
reduce recursions on CURVNET_SET() to a minimum, while still reducing
the scope of CURVNET_SET() to networking only operations - the
alternative would be calling CURVNET_SET() on each system call entry.
In general, curvnet has to be set in three typicall cases: when
processing socket-related requests from userspace or from within the
kernel; when processing inbound traffic flowing from device drivers
to upper layers of the networking stack, and when executing
timer-driven networking functions.

This change also introduces a DDB subcommand to show the list of all
vnet instances.

Approved by: julian (mentor)


# 187357 17-Jan-2009 jeff

- Implement generic macros for producing KTR records that are compatible
with src/tools/sched/schedgraph.py. This allows developers to quickly
create a graphical view of ktr data for any resource in the system.
- Add sched_tdname() and the pcpu field 'name' for quickly and uniformly
identifying records associated with a thread or cpu.
- Reimplement the KTR_SCHED traces using the new generic facility.

Obtained from: attilio
Discussed with: jhb
Sponsored by: Nokia


# 183054 15-Sep-2008 sam

Make ddb command registration dynamic so modules can extend
the command set (only so long as the module is present):
o add db_command_register and db_command_unregister to add and remove
commands, respectively
o replace linker sets with SYSINIT's (and SYSUINIT's) that register
commands
o expose 3 list heads: db_cmd_table, db_show_table, and db_show_all_table
for registering top-level commands, show operands, and show all operands,
respectively

While here also:
o sort command lists
o add DB_ALIAS, DB_SHOW_ALIAS, and DB_SHOW_ALL_ALIAS to add aliases
for existing commands
o add "show all trace" as an alias for "show alltrace"
o add "show all locks" as an alias for "show alllocks"

Submitted by: Guillaume Ballet <gballet@gmail.com> (original version)
Reviewed by: jhb
MFC after: 1 month


# 173600 14-Nov-2007 julian

generally we are interested in what thread did something as
opposed to what process. Since threads by default have teh name of the
process unless over-written with more useful information, just print the
thread name instead.


# 173444 08-Nov-2007 ups

Initial checkin for rmlock (read mostly lock) a multi reader single writer
lock optimized for almost exclusive reader access. (see also rmlock.9)

TODO:
Convert to per cpu variables linkerset as soon as it is available.
Optimize UP (single processor) case.


# 152021 03-Nov-2005 jhb

Fix 'show allpcpu' ddb command on non-x86. CPU IDs are in the range 0 ..
mp_maxid, not 0 .. mp_maxid - 1. The result was that the highest numbered
CPU was skipped on Alpha and sparc64.

MFC after: 1 week


# 150576 26-Sep-2005 rwatson

Add "show allpcpu" to DDB, which prints the current CPU id followed by
the per-cpu data for all CPUs. This is easier to ask users to do than
"figure out how many CPUs you have, now run show pcpu, then run it
once for each CPU you have".

MFC after: 3 days


# 139804 06-Jan-2005 imp

/* -> /*- for copyright notices, minor format tweaks as necessary


# 116182 11-Jun-2003 obrien

Use __FBSDID().


# 88901 05-Jan-2002 peter

Add a per-cpu variable, cpumask, the preshifted equivalent of 1 << cpuid.
We use this around the place a lot.


# 87702 11-Dec-2001 jhb

Overhaul the per-CPU support a bit:

- The MI portions of struct globaldata have been consolidated into a MI
struct pcpu. The MD per-CPU data are specified via a macro defined in
machine/pcpu.h. A macro was chosen over a struct mdpcpu so that the
interface would be cleaner (PCPU_GET(my_md_field) vs.
PCPU_GET(md.md_my_md_field)).
- All references to globaldata are changed to pcpu instead. In a UP kernel,
this data was stored as global variables which is where the original name
came from. In an SMP world this data is per-CPU and ideally private to each
CPU outside of the context of debuggers. This also included combining
machine/globaldata.h and machine/globals.h into machine/pcpu.h.
- The pointer to the thread using the FPU on i386 was renamed from
npxthread to fpcurthread to be identical with other architectures.
- Make the show pcpu ddb command MI with a MD callout to display MD
fields.
- The globaldata_register() function was renamed to pcpu_init() and now
init's MI fields of a struct pcpu in addition to registering it with
the internal array and list.
- A pcpu_destroy() function was added to remove a struct pcpu from the
internal array and list.

Tested on: alpha, i386
Reviewed by: peter, jake


# 85444 24-Oct-2001 jhb

Document the requirements and nature of the logical CPU IDs. It isn't
very strict and leaves much up to the platform so that it can define a
convenient mapping.

Requested by: mjacob


# 76440 10-May-2001 jhb

- Split out the support for per-CPU data from the SMP code. UP kernels
have per-CPU data and gdb on the i386 at least needs access to it.
- Clean up includes in kern_idle.c and subr_smp.c.

Reviewed by: jake