History log of /linux-master/arch/x86/include/asm/perf_event_p4.h
Revision Date Author Comments
# 8078f4d6 13-Feb-2024 Thomas Gleixner <tglx@linutronix.de>

x86/cpu/topology: Rename smp_num_siblings

It's really a non-intuitive name. Rename it to __max_threads_per_core which
is obvious.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Link: https://lore.kernel.org/r/20240213210253.011307973@linutronix.de


# b2441318 01-Nov-2017 Greg Kroah-Hartman <gregkh@linuxfoundation.org>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


# 4ba29684 26-Aug-2014 Christoph Lameter <cl@linux.com>

percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t

__get_cpu_var can paper over differences in the definitions of
cpumask_var_t and either use the address of the cpumask variable
directly or perform a fetch of the address of the struct cpumask
allocated elsewhere. This is important particularly when using per cpu
cpumask_var_t declarations because in one case we have an offset into
a per cpu area to handle and in the other case we need to fetch a
pointer from the offset.

This patch introduces a new macro

this_cpu_cpumask_var_ptr()

that is defined where cpumask_var_t is defined and performs the proper
actions. All use cases where __get_cpu_var is used with cpumask_var_t
are converted to the use of this_cpu_cpumask_var_ptr().

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>


# 5ac2b5c2 24-Apr-2013 Ingo Molnar <mingo@kernel.org>

perf/x86/intel/P4: Robistify P4 PMU types

Linus found, while extending integer type extension checks in the
sparse static code checker, various fragile patterns of mixed
signed/unsigned 64-bit/32-bit integer use in perf_events_p4.c.

The relevant hardware register ABI is 64 bit wide on 32-bit
kernels as well, so clean it all up a bit, remove unnecessary
casts, and make sure we use 64-bit unsigned integers in these
places.

[ Unfortunately this patch was not tested on real P4 hardware,
those are pretty rare already. If this patch causes any
problems on P4 hardware then please holler ... ]

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: David Miller <davem@davemloft.net>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20130424072630.GB1780@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>


# f53173e4 21-Jul-2011 Cyrill Gorcunov <gorcunov@gmail.com>

x86, perf: P4 PMU - Fix typos in comments and style cleanup

This patch:

- fixes typos in comments and clarifies the text
- renames obscure p4_event_alias::original and ::alter members to
::original and ::alternative as appropriate
- drops parenthesis from the return of p4_get_alias_event()

No functional changes.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Link: http://lkml.kernel.org/r/20110721160625.GX7492@sun
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# f9129870 08-Jul-2011 Cyrill Gorcunov <gorcunov@openvz.org>

perf, x86: P4 PMU - Introduce event alias feature

Instead of hw_nmi_watchdog_set_attr() weak function
and appropriate x86_pmu::hw_watchdog_set_attr() call
we introduce even alias mechanism which allow us
to drop this routines completely and isolate quirks
of Netburst architecture inside P4 PMU code only.

The main idea remains the same though -- to allow
nmi-watchdog and perf top run simultaneously.

Note the aliasing mechanism applies to generic
PERF_COUNT_HW_CPU_CYCLES event only because arbitrary
event (say passed as RAW initially) might have some
additional bits set inside ESCR register changing
the behaviour of event and we can't guarantee anymore
that alias event will give the same result.

P.S. Thanks a huge to Don and Steven for for testing
and early review.

Acked-by: Don Zickus <dzickus@redhat.com>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: Ingo Molnar <mingo@elte.hu>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Stephane Eranian <eranian@google.com>
CC: Lin Ming <ming.m.lin@intel.com>
CC: Arnaldo Carvalho de Melo <acme@redhat.com>
CC: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20110708201712.GS23657@sun
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>


# 0d2eb44f 17-Mar-2011 Lucas De Marchi <lucas.de.marchi@gmail.com>

x86: Fix common misspellings

They were generated by 'codespell' and then manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: trivial@kernel.org
LKML-Reference: <1300389856-1099-3-git-send-email-lucas.demarchi@profusion.mobi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# 7d44ec19 16-Feb-2011 Cyrill Gorcunov <gorcunov@openvz.org>

perf, x86: P4 PMU: Fix spurious NMI messages

Several people have reported spurious unknown NMI
messages on some P4 CPUs.

This patch fixes it by checking for an overflow (negative
counter values) directly, instead of relying on the
P4_CCCR_OVF bit.

Reported-by: George Spelvin <linux@horizon.com>
Reported-by: Meelis Roos <mroos@linux.ee>
Reported-by: Don Zickus <dzickus@redhat.com>
Reported-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <AANLkTinfuTfCck_FfaOHrDqQZZehtRzkBum4SpFoO=KJ@mail.gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# 047a3772 07-Jan-2011 Cyrill Gorcunov <gorcunov@gmail.com>

perf, x86: P4 PMU - Fix unflagged overflows handling

Don found that P4 PMU reads CCCR register instead of counter
itself (in attempt to catch unflagged event) this makes P4
NMI handler to consume all NMIs it observes. So the other
NMI users such as kgdb simply have no chance to get NMI
on their hands.

Side note: at moment there is no way to run nmi-watchdog
together with perf tool. This is because both 'perf top' and
nmi-watchdog use same event. So while nmi-watchdog reserves
one event/counter for own needs there is no room for perf tool
left (there is a way to disable nmi-watchdog on boot of course).

Ming has tested this patch with the following results

| 1. watchdog disabled
|
| kgdb tests on boot OK
| perf works OK
|
| 2. watchdog enabled, without patch perf-x86-p4-nmi-4
|
| kgdb tests on boot hang
|
| 3. watchdog enabled, without patch perf-x86-p4-nmi-4 and do not run kgdb
| tests on boot
|
| "perf top" partialy works
| cpu-cycles no
| instructions yes
| cache-references no
| cache-misses no
| branch-instructions no
| branch-misses yes
| bus-cycles no
|
| 4. watchdog enabled, with patch perf-x86-p4-nmi-4 applied
|
| kgdb tests on boot OK
| perf does not work, NMI "Dazed and confused" messages show up
|

Which means we still have problems with p4 box due to 'unknown'
nmi happens but at least it should fix kgdb test cases.

Reported-by: Jason Wessel <jason.wessel@windriver.com>
Reported-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Don Zickus <dzickus@redhat.com>
Acked-by: Lin Ming <ming.m.lin@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <4D275E7E.3040903@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# af86da53 26-Nov-2010 Cyrill Gorcunov <gorcunov@openvz.org>

perf, x86: P4 PMU - describe config format

Add description of .config in a sake of RAW events.
At least this should bring some light to those who
will be reading this code.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: Stephane Eranian <eranian@google.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# c9cf4a01 25-Aug-2010 Cyrill Gorcunov <gorcunov@openvz.org>

perf, x86, Pentium4: Add RAW events verification

Implements verification of

- Bits of ESCR EventMask field (meaningful bits in field are hardware
predefined and others bits should be set to zero)

- INSTR_COMPLETED event (it is available on predefined cpu model only)

- Thread shared events (they should be guarded by "perf_event_paranoid"
sysctl due to security reason). The side effect of this action is
that PERF_COUNT_HW_BUS_CYCLES become a "paranoid" general event.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Lin Ming <ming.m.lin@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20100825182334.GB14874@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# 39ef13a4 04-Jul-2010 Cyrill Gorcunov <gorcunov@openvz.org>

perf, x86: P4 PMU -- redesign cache events

To support cache events we have reserved the low 6 bits in
hw_perf_event::config (which is a part of CCCR register
configuration actually).

These bits represent Replay Event mertic enumerated in
enum P4_PEBS_METRIC. The caller should not care about
which exact bits should be set and how -- the caller
just chooses one P4_PEBS_METRIC entity and puts it into
the config. The kernel will track it and set appropriate
additional MSR registers (metrics) when needed.

The reason for this redesign was the PEBS enable bit, which
should not be set until DS (and PEBS sampling) support will
be implemented properly.

TODO
====

- PEBS sampling (note it's tricky and works with _one_ counter only
so for HT machines it will be not that easy to handle both threads)

- tracking of PEBS registers state, a user might need to turn
PEBS off completely (ie no PEBS enable, no UOP_tag) but some
other event may need it, such events clashes and should not
run simultaneously, at moment we just don't support such events

- eventually export user space bits in separate header which will
allow user apps to configure raw events more conveniently.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1278295769.9540.15.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# ce7f1545 18-May-2010 Cyrill Gorcunov <gorcunov@openvz.org>

perf, x86: P4 PMU -- add missing bit in CCCR mask

Should be there for the sake of RAW events.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: Lin Ming <ming.m.lin@intel.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100518212439.354345151@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# d814f301 23-Mar-2010 Cyrill Gorcunov <gorcunov@openvz.org>

x86, perf: Add raw events support for the P4 PMU

The adding of raw event support lead to complete code
refactoring. I hope is became more readable then it was.

The list of changes:

1) The 64bit config field is enough to hold all information we need
to track event details. To achieve it we used *own* enum for
events selection in ESCR register and map this key into proper
value at moment of event enabling.

For the same reason we use 12LSB bits in CCCR register -- to track
which exactly cache trace event was requested. And we cear this bits
at real 'write' moment.

2) There is no per-cpu area reserved for P4 PMU anymore. We
don't need it. All is held by config.

3) Now we may use any available counter, ie we try to grab any
possible counter.

v2:
- Lin Ming reported the lack of ESCR selector in CCCR for cache events

v3:
- Don't loose cache event codes at config unpacking procedure, we may
need it one day so no obscure hack behind our back, better to clear
reserved bits explicitly when needed (thanks Ming for pointing out)

- Lin Ming fixed misplaced opcodes in cache events

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1269403766.3409.6.camel@minggr.sh.intel.com>
[ v4: did a few whitespace fixlets ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# 40b7e05e 19-Mar-2010 Lin Ming <ming.m.lin@intel.com>

perf, x86: Fix key indexing in Pentium-4 PMU

Index 0-6 in p4_templates are reserved for common hardware
events. So p4_templates is arranged as below:

0 - 6: common hardware events
7 - N: cache events
N+1 - ...: other raw events

Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1268983738.13901.142.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# 9c8c6bad 18-Mar-2010 Cyrill Gorcunov <gorcunov@gmail.com>

x86, perf: Fix few cosmetic dabs for P4 pmu (comments and constantify)

- A few ESCR have escaped fixing at previous attempt.
- p4_escr_map is read only, make it const.

Nothing serious.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Lin Ming <ming.m.lin@intel.com>
LKML-Reference: <20100318211256.GH5062@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# cb7d6b50 18-Mar-2010 Lin Ming <ming.m.lin@intel.com>

perf, x86: Add cache events for the Pentium-4 PMU

Move the HT bit setting code from p4_pmu_event_map to
p4_hw_config. So the cache events can get HT bit set correctly.

Tested on my P4 desktop, below 6 cache events work:

L1-dcache-load-misses
LLC-load-misses
dTLB-load-misses
dTLB-store-misses
iTLB-loads
iTLB-load-misses

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1268908392.13901.128.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# f34edbc1 18-Mar-2010 Lin Ming <ming.m.lin@intel.com>

perf, x86: Add a key to simplify template lookup in Pentium-4 PMU

Currently, we use opcode(Event and Event-Selector) + emask to
look up template in p4_templates.

But cache events (L1-dcache-load-misses, LLC-load-misses, etc)
use the same event(P4_REPLAY_EVENT) to do the counting, ie, they
have the same opcode and emask. So we can not use current lookup
mechanism to find the template for cache events.

This patch introduces a "key", which is the index into
p4_templates. The low 12 bits of CCCR are reserved, so we can
hide the "key" in the low 12 bits of hwc->config.

We extract the key from hwc->config and then quickly find the
template.

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1268908387.13901.127.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# 8ea7f544 15-Mar-2010 Lin Ming <ming.m.lin@intel.com>

x86, perf: Fix comments in Pentium-4 PMU definitions

Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1268705556.3379.8.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# e4495262 14-Mar-2010 Cyrill Gorcunov <gorcunov@openvz.org>

perf, x86: Enable not tagged retired instruction counting on P4s

This should turn on instruction counting on P4s, which was missing in
the first version of the new PMU driver.

It's inaccurate for now, we still need dependant event to tag mops
before we can count them precisely. The result is that the number of
instruction may be lifted up.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1268629102.3355.11.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


# a072738e 11-Mar-2010 Cyrill Gorcunov <gorcunov@openvz.org>

perf, x86: Implement initial P4 PMU driver

The netburst PMU is way different from the "architectural
perfomance monitoring" specification that current CPUs use.
P4 uses a tuple of ESCR+CCCR+COUNTER MSR registers to handle
perfomance monitoring events.

A few implementational details:

1) We need a separate x86_pmu::hw_config helper in struct
x86_pmu since register bit-fields are quite different from P6,
Core and later cpu series.

2) For the same reason is a x86_pmu::schedule_events helper
introduced.

3) hw_perf_event::config consists of packed ESCR+CCCR values.
It's allowed since in reality both registers only use a half
of their size. Of course before making a real write into a
particular MSR we need to unpack the value and extend it to
a proper size.

4) The tuple of packed ESCR+CCCR in hw_perf_event::config
doesn't describe the memory address of ESCR MSR register
so that we need to keep a mapping between these tuples
used and available ESCR (various P4 events may use same
ESCRs but not simultaneously), for this sake every active
event has a per-cpu map of hw_perf_event::idx <--> ESCR
addresses.

5) Since hw_perf_event::idx is an offset to counter/control register
we need to lift X86_PMC_MAX_GENERIC up, otherwise kernel
strips it down to 8 registers and event armed may never be turned
off (ie the bit in active_mask is set but the loop never reaches
this index to check), thanks to Peter Zijlstra

Restrictions:

- No cascaded counters support (do we ever need them?)
- No dependent events support (so PERF_COUNT_HW_INSTRUCTIONS
doesn't work for now)
- There are events with same counters which can't work simultaneously
(need to use intersected ones due to broken counter 1)
- No PERF_COUNT_HW_CACHE_ events yet

Todo:

- Implement dependent events
- Need proper hashing for event opcodes (no linear search, good for
debugging stage but not in real loads)
- Some events counted during a clock cycle -- need to set threshold
for them and count every clock cycle just to get summary statistics
(ie to behave the same way as other PMUs do)
- Need to swicth to use event_constraints
- To support RAW events we need to encode a global list of P4 events
into p4_templates
- Cache events need to be added

Event support status matrix:

Event status
-----------------------------
cycles works
cache-references works
cache-misses works
branch-misses works
bus-cycles partially (does not work on 64bit cpu with HT enabled)
instruction doesnt work (needs dependent event [mop tagging])
branches doesnt work

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100311165439.GB5129@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>