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Message-ID: <CAP-5=fUsK9+d0=f2RuTQBfooVZ6qTPZ=XQZ_z7DaH08FG6tV9w@mail.gmail.com> Date: Thu, 30 Oct 2025 13:51:39 -0700 From: Ian Rogers <irogers@...gle.com> To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, James Clark <james.clark@...aro.org>, Xu Yang <xu.yang_2@....com>, Chun-Tse Shao <ctshao@...gle.com>, Thomas Richter <tmricht@...ux.ibm.com>, Sumanth Korikkar <sumanthk@...ux.ibm.com>, Collin Funk <collin.funk1@...il.com>, Thomas Falcon <thomas.falcon@...el.com>, Howard Chu <howardchu95@...il.com>, Dapeng Mi <dapeng1.mi@...ux.intel.com>, Levi Yun <yeoreum.yun@....com>, Yang Li <yang.lee@...ux.alibaba.com>, linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>, Weilin Wang <weilin.wang@...el.com> Subject: Re: [PATCH v1 00/22] Switch the default perf stat metrics to json On Fri, Oct 24, 2025 at 10:59 AM Ian Rogers <irogers@...gle.com> wrote: > > Prior to this series stat-shadow would produce hard coded metrics if > certain events appeared in the evlist. This series produces equivalent > json metrics and cleans up the consequences in tests and display > output. A before and after of the default display output on a > tigerlake is: > > Before: > ``` > $ perf stat -a sleep 1 > > Performance counter stats for 'system wide': > > 16,041,816,418 cpu-clock # 15.995 CPUs utilized > 5,749 context-switches # 358.376 /sec > 121 cpu-migrations # 7.543 /sec > 1,806 page-faults # 112.581 /sec > 825,965,204 instructions # 0.70 insn per cycle > 1,180,799,101 cycles # 0.074 GHz > 168,945,109 branches # 10.532 M/sec > 4,629,567 branch-misses # 2.74% of all branches > # 30.2 % tma_backend_bound > # 7.8 % tma_bad_speculation > # 47.1 % tma_frontend_bound > # 14.9 % tma_retiring > ``` > > After: > ``` > $ perf stat -a sleep 1 > > Performance counter stats for 'system wide': > > 2,890 context-switches # 179.9 cs/sec cs_per_second > 16,061,923,339 cpu-clock # 16.0 CPUs CPUs_utilized > 43 cpu-migrations # 2.7 migrations/sec migrations_per_second > 5,645 page-faults # 351.5 faults/sec page_faults_per_second > 5,708,413 branch-misses # 1.4 % branch_miss_rate (88.83%) > 429,978,120 branches # 26.8 K/sec branch_frequency (88.85%) > 1,626,915,897 cpu-cycles # 0.1 GHz cycles_frequency (88.84%) > 2,556,805,534 instructions # 1.5 instructions insn_per_cycle (88.86%) > TopdownL1 # 20.1 % tma_backend_bound > # 40.5 % tma_bad_speculation (88.90%) > # 17.2 % tma_frontend_bound (78.05%) > # 22.2 % tma_retiring (88.89%) > > 1.002994394 seconds time elapsed > ``` > > Having the metrics in json brings greater uniformity, allows events to > be shared by metrics, and it also allows descriptions like: > ``` > $ perf list cs_per_second > ... > cs_per_second > [Context switches per CPU second] > ``` > > A thorn in the side of doing this work was that the hard coded metrics > were used by perf script with '-F metric'. This functionality didn't > work for me (I was testing `perf record -e instructions,cycles` and > then `perf script -F metric` but saw nothing but empty lines) but > anyway I decided to fix it to the best of my ability in this > series. So the script side counters were removed and the regular ones > associated with the evsel used. The json metrics were all searched > looking for ones that have a subset of events matching those in the > perf script session, and all metrics are printed. This is kind of > weird as the counters are being set by the period of samples, but I > carried the behavior forward. I suspect there needs to be follow up > work to make this better, but what is in the series is superior to > what is currently in the tree. Follow up work could include finding > metrics for the machine in the perf.data rather than using the host, > allowing multiple metrics even if the metric ids of the events differ, > fixing pre-existing `perf stat record/report` issues, etc. > > There is a lot of stat tests that, for example, assume '-e > instructions,cycles' will produce an IPC metric. These things needed > tidying as now the metric must be explicitly asked for and when doing > this ones using software events were preferred to increase > compatibility. As the test updates were numerous they are distinct to > the patches updating the functionality causing periods in the series > where not all tests are passing. If this is undesirable the test fixes > can be squashed into the functionality updates. Hi, no comments on this series yet, please help! I'd like to land this work and then rebase the python generating metric work [1] on it. The metric generation work is largely independent of everything else but there are collisions in the json Makefile/Build files. Thanks, Ian [1] * Foundations: https://lore.kernel.org/lkml/20240228175617.4049201-1-irogers@google.com/ * AMD: https://lore.kernel.org/lkml/20240229001537.4158049-1-irogers@google.com/ * Intel: https://lore.kernel.org/lkml/20240229001806.4158429-1-irogers@google.com/ * ARM: https://lore.kernel.org/lkml/20240229001325.4157655-1-irogers@google.com/ > Ian Rogers (22): > perf evsel: Remove unused metric_events variable > perf metricgroup: Update comment on location of metric_event list > perf metricgroup: Missed free on error path > perf metricgroup: When copy metrics copy default information > perf metricgroup: Add care to picking the evsel for displaying a > metric > perf jevents: Make all tables static > perf expr: Add #target_cpu literal > perf jevents: Add set of common metrics based on default ones > perf jevents: Add metric DefaultShowEvents > perf stat: Add detail -d,-dd,-ddd metrics > perf script: Change metric format to use json metrics > perf stat: Remove hard coded shadow metrics > perf stat: Fix default metricgroup display on hybrid > perf stat: Sort default events/metrics > perf stat: Remove "unit" workarounds for metric-only > perf test stat+json: Improve metric-only testing > perf test stat: Ignore failures in Default[234] metricgroups > perf test stat: Update std_output testing metric expectations > perf test metrics: Update all metrics for possibly failing default > metrics > perf test stat: Update shadow test to use metrics > perf test stat: Update test expectations and events > perf test stat csv: Update test expectations and events > > tools/perf/builtin-script.c | 238 ++++++++++- > tools/perf/builtin-stat.c | 154 ++----- > .../arch/common/common/metrics.json | 151 +++++++ > tools/perf/pmu-events/empty-pmu-events.c | 139 ++++-- > tools/perf/pmu-events/jevents.py | 34 +- > tools/perf/pmu-events/pmu-events.h | 2 + > .../tests/shell/lib/perf_json_output_lint.py | 4 +- > tools/perf/tests/shell/lib/stat_output.sh | 2 +- > tools/perf/tests/shell/stat+csv_output.sh | 2 +- > tools/perf/tests/shell/stat+json_output.sh | 2 +- > tools/perf/tests/shell/stat+shadow_stat.sh | 4 +- > tools/perf/tests/shell/stat+std_output.sh | 4 +- > tools/perf/tests/shell/stat.sh | 6 +- > .../perf/tests/shell/stat_all_metricgroups.sh | 3 + > tools/perf/tests/shell/stat_all_metrics.sh | 7 +- > tools/perf/util/evsel.c | 2 - > tools/perf/util/evsel.h | 2 +- > tools/perf/util/expr.c | 3 + > tools/perf/util/metricgroup.c | 95 ++++- > tools/perf/util/metricgroup.h | 2 +- > tools/perf/util/stat-display.c | 55 +-- > tools/perf/util/stat-shadow.c | 402 +----------------- > tools/perf/util/stat.h | 2 +- > 23 files changed, 672 insertions(+), 643 deletions(-) > create mode 100644 tools/perf/pmu-events/arch/common/common/metrics.json > > -- > 2.51.1.821.gb6fe4d2222-goog >
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