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Message-ID: <c0648b32-e450-4036-aebe-5faab7edc1bd@linux.intel.com>
Date: Mon, 10 Nov 2025 16:38:08 +0800
From: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
To: Ian Rogers <irogers@...gle.com>, 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>, 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>,
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 v2 00/18] Switch the default perf stat metrics to json
Hi Ian,
which commit is the patch-set based on? I tried to apply this patch-set on
perf-tools-next branch, but it fails...
Thanks,
-Dapeng
On 11/7/2025 7:14 AM, Ian Rogers 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`
> with/without leader sampling 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, but this will be kind
> of messy, especially as at some points in the series both the old
> metrics and the new metrics will be displayed.
>
> v2: Drop merged patches, add json to document target_cpu/core_wide and
> example to "Add care to picking the evsel for displaying a metric"
> commit message (Namhyung).
>
> v1: https://lore.kernel.org/lkml/20251024175857.808401-1-irogers@google.com/
>
> Ian Rogers (18):
> perf metricgroup: Add care to picking the evsel for displaying a
> metric
> 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
> perf tool_pmu: Make core_wide and target_cpu json events
>
> tools/perf/builtin-script.c | 238 ++++++++++-
> tools/perf/builtin-stat.c | 154 ++-----
> .../arch/common/common/metrics.json | 151 +++++++
> .../pmu-events/arch/common/common/tool.json | 12 +
> tools/perf/pmu-events/empty-pmu-events.c | 229 ++++++----
> tools/perf/pmu-events/jevents.py | 28 +-
> 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.h | 1 +
> tools/perf/util/expr.c | 8 +-
> tools/perf/util/metricgroup.c | 92 +++-
> tools/perf/util/stat-display.c | 55 +--
> tools/perf/util/stat-shadow.c | 404 +-----------------
> tools/perf/util/stat.h | 2 +-
> tools/perf/util/tool_pmu.c | 24 +-
> tools/perf/util/tool_pmu.h | 9 +-
> 24 files changed, 756 insertions(+), 687 deletions(-)
> create mode 100644 tools/perf/pmu-events/arch/common/common/metrics.json
>
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