Date: Wed, 26 Jun 2024 18:17:22 +0000
From: "Wang, Weilin" <weilin.wang@...el.com>
To: Namhyung Kim <namhyung@...nel.org>
CC: Ian Rogers <irogers@...gle.com>, Arnaldo Carvalho de Melo
	<acme@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar
	<mingo@...hat.com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, "Hunter, Adrian" <adrian.hunter@...el.com>,
	"Kan Liang" <kan.liang@...ux.intel.com>, "linux-perf-users@...r.kernel.org"
	<linux-perf-users@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Taylor, Perry" <perry.taylor@...el.com>,
	"Alt, Samantha" <samantha.alt@...el.com>, "Biggers, Caleb"
	<caleb.biggers@...el.com>
Subject: RE: [RFC PATCH v14 0/8] TPEBS counting mode support



> -----Original Message-----
> From: Namhyung Kim <namhyung@...nel.org>
> Sent: Wednesday, June 26, 2024 10:59 AM
> To: Wang, Weilin <weilin.wang@...el.com>
> Cc: Ian Rogers <irogers@...gle.com>; Arnaldo Carvalho de Melo
> <acme@...nel.org>; Peter Zijlstra <peterz@...radead.org>; Ingo Molnar
> <mingo@...hat.com>; Alexander Shishkin
> <alexander.shishkin@...ux.intel.com>; Jiri Olsa <jolsa@...nel.org>; Hunter,
> Adrian <adrian.hunter@...el.com>; Kan Liang <kan.liang@...ux.intel.com>;
> linux-perf-users@...r.kernel.org; linux-kernel@...r.kernel.org; Taylor, Perry
> <perry.taylor@...el.com>; Alt, Samantha <samantha.alt@...el.com>; Biggers,
> Caleb <caleb.biggers@...el.com>
> Subject: Re: [RFC PATCH v14 0/8] TPEBS counting mode support
> 
> On Mon, Jun 24, 2024 at 06:20:16PM -0400, weilin.wang@...el.com wrote:
> > From: Weilin Wang <weilin.wang@...el.com>
> >
> > Changes in v14:
> >  - Fix the python import test failure. We cannot support PYTHON_PERF
> because it
> >  will trigger a chain of dependency issues if we add intel-tpebs.c to it. So,
> >  only enable tpebs functions in evsel and evlist when PYTHON_PERF is not
> >  defined.
> 
> I think it's easier if we have Ian's python build cleanup first.
> 
>   https://lore.kernel.org/linux-perf-users/20240625214117.953777-1-
> irogers@...gle.com
> 
> Let me take a look at it..

Ok, I will hold the cmd option name update until we conclude on this one. 
Thanks a lot!

Thanks,
Weilin

> 
> Thanks,
> Namhyung
> 
> 
> >  - Fix shellcheck warning for the tpebs test.
> >
> > Changes in v13:
> >  - Add document for the command line option and fix build error in non-
> x86_64.
> >  - Update example with non-zero retire_latency value when tpebs recording
> is
> >  enabled.
> >  - Add tpebs_stop() back to tpebs_set_evsel() because in hybrid platform,
> when
> >  the forked perf record is not killed, the reader thread does not get any
> >  sampled data from the PIPE. As a result, tpebs_set_evesel() will always
> return
> >  zero on retire_latency values. This does not happen on my test GNR
> machine.
> >  Since -I is not supported yet, I think we should add tpebs_stop() to ensure
> >  correctness for now. More investigation is required here when we work on
> >  supporting -I mode.
> >  - Rebase code on top of perf-tools-next.
> >
> > Changes in v12:
> >  - Update MTL metric JSON file to include E-Core TMA3.6 changes.
> >  - Update comments and code for better code quality. Keep tpebs_start() and
> >  tpebs_delete() at evsel level for now and add comments on these functions
> with
> >  more details about potential future changes. Remove tpebs_stop() call from
> >  tpebs_set_evsel(). Simplify the tpebs_start() and
> tpebs_stop()/tpebs_delete()
> >  interfaces. Also fixed the bugs on not freed "new" pointer and the incorrect
> >  variable value assignment to val instead of counter->val.
> >
> > Changes in v11:
> >  - Make retire_latency evsels not opened for counting. This works correctly
> now
> >  with the code Namhyung suggested that adjusting group read size when
> >  retire_latency evsels included in the group.
> >  - Update retire_latency value assignment using rint() to reduce precision loss
> >  while keeping code generic.
> >  - Fix the build error caused by not used variable in the test.
> >
> > Other changes in v10:
> >  - Change perf record fork from perf stat to evsel. All the major operations
> >  like tpebs start, stop, read_evsel should directly work through evsel.
> >  - Make intel-tpebs x86_64 only. This change is cross-compiled to arm64.
> >  - Put tpebs code to intel-tepbs and simplify intel-tpebs APIs to minimum
> number
> > of functions and variables. Update funtion name and variable names to use
> > consistent prefix. Also improve error handling.
> >  - Integrate code patch from Ian for the :R parser.
> >  - Update MTL metrics to TMA 4.8.
> >
> > V9: https://lore.kernel.org/all/20240521173952.3397644-1-
> weilin.wang@...el.com/
> >
> > Changes in v9:
> >  - Update the retire_latency result print and metric calculation method.
> Plugin
> > the value to evsel so that no special code is required.
> >  - Update --control:fifo to use pipe instead of named pipe.
> >  - Add test for TPEBS counting mode.
> >  - Update Document with more details.
> >
> > Changes in v8:
> >  - In this revision, the code is updated to base on Ian's patch on R modifier
> > parser https://lore.kernel.org/lkml/20240428053616.1125891-3-
> irogers@...gle.com/
> > After this change, there is no special code required for R modifier in
> > metricgroup.c and metricgroup.h files.
> >
> > Caveat of this change:
> >   Ideally, we will need to add special handling to skip counting events with R
> > modifier in evsel. Currently, this is not implemented so the event with :R will
> > be both counted and sampled. Usually, in a metric formula that uses
> retire_latency,
> > it would already require to count the event. As a result, we will endup count
> the
> > same event twice. This should be able to be handled properly when we
> finalize our
> > design on evsel R modifier support.
> >
> >  - Move TPEBS specific code out from main perf stat code to separate files in
> > util/intel-tpebs.c and util/intel-tpebs.h. [Namhyung]
> >  - Use --control:fifo to ack perf stat from forked perf record instead of
> sleep(2) [Namhyung]
> >  - Add introductions about TPEBS and R modifier in Documents. [Namhyung]
> >
> >
> > Changes in v7:
> >  - Update code and comments for better code quality [Namhyung]
> >  - Add a separate commit for perf data [Namhyung]
> >  - Update retire latency print function to improve alignment [Namhyung]
> >
> > Changes in v6:
> >  - Update code and add comments for better code quality [Namhyung]
> >  - Remove the added fd var and directly pass the opened fd to data.file.fd
> [Namhyung]
> >  - Add kill() to stop perf record when perf stat exists early [Namhyung]
> >  - Add command opt check to ensure only start perf record when -a/-C given
> [Namhyung]
> >  - Squash commits [Namhyung]
> >
> > Changes in v5:
> >  - Update code and add comments for better code quality [Ian]
> >
> > Changes in v4:
> >  - Remove uncessary debug print and update code and comments for better
> > readability and quality [Namhyung]
> >  - Update mtl metric json file with consistent TmaL1 and TopdownL1
> metricgroup
> >
> > Changes in v3:
> >  - Remove ':' when event name has '@' [Ian]
> >  - Use 'R' as the modifier instead of "retire_latency" [Ian]
> >
> > Changes in v2:
> >  - Add MTL metric file
> >  - Add more descriptions and example to the patch [Arnaldo]
> >
> > Here is an example of running perf stat to collect a metric that uses
> > retire_latency value of event MEM_INST_RETIRED.STLB_HIT_STORES on a
> MTL system.
> >
> > In this simple example, there is no MEM_INST_RETIRED.STLB_HIT_STORES
> sample.
> > Therefore, the MEM_INST_RETIRED.STLB_HIT_STORES:p count and
> retire_latency value
> > are all 0.
> >
> > ./perf stat -M tma_dtlb_store -a -- sleep 1
> >
> > [ perf record: Woken up 1 times to write data ]
> > [ perf record: Captured and wrote 0.000 MB - ]
> >
> >  Performance counter stats for 'system wide':
> >
> >        181,047,168      cpu_core/TOPDOWN.SLOTS/          #      0.6 %
> tma_dtlb_store
> >          3,195,608      cpu_core/topdown-retiring/
> >         40,156,649      cpu_core/topdown-mem-bound/
> >          3,550,925      cpu_core/topdown-bad-spec/
> >        117,571,818      cpu_core/topdown-fe-bound/
> >         57,118,087      cpu_core/topdown-be-bound/
> >             69,179      cpu_core/EXE_ACTIVITY.BOUND_ON_STORES/
> >              4,582      cpu_core/MEM_INST_RETIRED.STLB_HIT_STORES/
> >         30,183,104      cpu_core/CPU_CLK_UNHALTED.DISTRIBUTED/
> >         30,556,790      cpu_core/CPU_CLK_UNHALTED.THREAD/
> >            168,486      cpu_core/DTLB_STORE_MISSES.WALK_ACTIVE/
> >               0.00 MEM_INST_RETIRED.STLB_HIT_STORES:p       0        0
> >
> >        1.003105924 seconds time elapsed
> >
> > v1:
> > TPEBS is one of the features provided by the next generation of Intel PMU.
> > Please refer to Section 8.4.1 of "Intel® Architecture Instruction Set
> Extensions
> > Programming Reference" [1] for more details about this feature.
> >
> > This set of patches supports TPEBS in counting mode. The code works in the
> > following way: it forks a perf record process from perf stat when
> retire_latency
> > of one or more events are used in a metric formula. Perf stat would send a
> > SIGTERM signal to perf record before it needs the retire latency value for
> > metric calculation. Perf stat will then process sample data to extract the
> > retire latency data for metric calculations. Currently, the code uses the
> > arithmetic average of retire latency values.
> >
> > [1] https://www.intel.com/content/www/us/en/content-
> details/812218/intel-architecture-instruction-set-extensions-programming-
> reference.html?wapkw=future%20features
> >
> >
> > Ian Rogers (1):
> >   perf parse-events: Add a retirement latency modifier
> >
> > Weilin Wang (7):
> >   perf data: Allow to use given fd in data->file.fd
> >   perf stat: Fork and launch perf record when perf stat needs to get
> >     retire latency value for a metric.
> >   perf stat: Plugin retire_lat value from sampled data to evsel
> >   perf vendor events intel: Add MTL metric json files
> >   perf stat: Add command line option for enabling tpebs recording
> >   perf Document: Add TPEBS to Documents
> >   perf test: Add test for Intel TPEBS counting mode
> >
> >  tools/perf/Documentation/perf-list.txt        |    1 +
> >  tools/perf/Documentation/perf-stat.txt        |    8 +
> >  tools/perf/Documentation/topdown.txt          |   30 +
> >  tools/perf/arch/x86/util/evlist.c             |    6 +
> >  tools/perf/builtin-stat.c                     |    8 +
> >  .../arch/x86/meteorlake/metricgroups.json     |  142 +
> >  .../arch/x86/meteorlake/mtl-metrics.json      | 2535 +++++++++++++++++
> >  .../perf/tests/shell/test_stat_intel_tpebs.sh |   18 +
> >  tools/perf/util/Build                         |    1 +
> >  tools/perf/util/data.c                        |    7 +-
> >  tools/perf/util/evlist.c                      |    4 +
> >  tools/perf/util/evsel.c                       |   91 +-
> >  tools/perf/util/evsel.h                       |    6 +
> >  tools/perf/util/intel-tpebs.c                 |  407 +++
> >  tools/perf/util/intel-tpebs.h                 |   35 +
> >  tools/perf/util/parse-events.c                |    2 +
> >  tools/perf/util/parse-events.h                |    1 +
> >  tools/perf/util/parse-events.l                |    3 +-
> >  18 files changed, 3301 insertions(+), 4 deletions(-)
> >  create mode 100644 tools/perf/pmu-
> events/arch/x86/meteorlake/metricgroups.json
> >  create mode 100644 tools/perf/pmu-events/arch/x86/meteorlake/mtl-
> metrics.json
> >  create mode 100755 tools/perf/tests/shell/test_stat_intel_tpebs.sh
> >  create mode 100644 tools/perf/util/intel-tpebs.c
> >  create mode 100644 tools/perf/util/intel-tpebs.h
> >
> > --
> > 2.43.0
> >

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