linux-kernel - Re: [PATCH v1 0/2] Fix incorrect counts when count the same uncore event multiple times

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Message-ID: <CAP-5=fUAd5rjXp7evGLqm+gk4yjq+eoGaHNCkaAYNEcKonb4gA@mail.gmail.com>
Date: Thu, 27 Mar 2025 08:11:11 -0700
From: Ian Rogers <irogers@...gle.com>
To: Chun-Tse Shao <ctshao@...gle.com>
Cc: linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...hat.com, 
	acme@...nel.org, namhyung@...nel.org, mark.rutland@....com, 
	alexander.shishkin@...ux.intel.com, jolsa@...nel.org, adrian.hunter@...el.com, 
	kan.liang@...ux.intel.com, james.clark@...aro.org, howardchu95@...il.com, 
	linux@...blig.org, yeoreum.yun@....com, ak@...ux.intel.com, 
	weilin.wang@...el.com, asmadeus@...ewreck.org, 
	linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v1 0/2] Fix incorrect counts when count the same uncore
 event multiple times

On Wed, Mar 26, 2025 at 4:49 PM Chun-Tse Shao <ctshao@...gle.com> wrote:
>
> Let's take a look an example, the machine is SKX with 6 IMC devices.
>
>   perf stat -e clockticks,clockticks -I 1000
>   #           time             counts unit events
>        1.001127430      6,901,503,174      uncore_imc_0/clockticks/
>        1.001127430      3,940,896,301      uncore_imc_0/clockticks/
>        2.002649722        988,376,876      uncore_imc_0/clockticks/
>        2.002649722        988,376,141      uncore_imc_0/clockticks/
>        3.004071319      1,000,292,675      uncore_imc_0/clockticks/
>        3.004071319      1,000,294,160      uncore_imc_0/clockticks/
>
> 1) The events name should not be uniquified.
> 2) The initial count for the first `clockticks` is doubled.
> 3) Subsequent count only report for the first IMC device.
>
> The first patch fixes 1) and 3), and the second patch fixes 2).
>
> After these fix:
>
>   perf stat -e clockticks,clockticks -I 1000
>   #           time             counts unit events
>        1.001127586      4,126,938,857      clockticks
>        1.001127586      4,121,564,277      clockticks
>        2.001686014      3,953,806,350      clockticks
>        2.001686014      3,953,809,541      clockticks
>        3.003121403      4,137,750,252      clockticks
>        3.003121403      4,137,749,048      clockticks
>
> I also tested `-A`, `--per-socket`, `--per-die` and `--per-core`, all
> looks good.

Thanks CT, I tested on hybrid and it looks good. I did notice a
regression with hwmon:

Before:
```
$ perf stat -e data_read,temp1 -a sleep 0.1

Performance counter stats for 'system wide':

           212.12 MiB  data_read
18,446,744,073,709,284.00 'C   hwmon_acpitz/temp1/
            46.00 'C   hwmon_coretemp/temp1/
            32.00 'C   hwmon_iwlwifi_1/temp1/
            40.85 'C   hwmon_nvme/temp1/
            47.00 'C   hwmon_spd5118/temp1/
```

After:
```
$  perf stat -e data_read,temp1 -a sleep 0.1

Performance counter stats for 'system wide':

           213.08 MiB  data_read
18,446,744,073,709,448.00 'C   temp1
```

So we're not uniquifying the hwmon events any more, I'll look into a
fix. I also need to open a bug to use my acptiz device to solve the
world's energy problems as it is currently running with 5% of the
surface temperature of the Sun.

Thanks,
Ian

> Ian Rogers (2):
>   perf evlist: Make uniquifying counter names consistent
>   perf parse-events: Use wildcard processing to set an event to merge
>     into
>
>  tools/perf/builtin-record.c    |   7 +-
>  tools/perf/builtin-top.c       |   7 +-
>  tools/perf/util/evlist.c       |  66 +++++++++-----
>  tools/perf/util/evlist.h       |   3 +-
>  tools/perf/util/evsel.c        | 116 ++++++++++++++++++++++++-
>  tools/perf/util/evsel.h        |  11 ++-
>  tools/perf/util/parse-events.c |  45 ++++++----
>  tools/perf/util/stat-display.c | 151 +--------------------------------
>  tools/perf/util/stat.c         |  40 +--------
>  9 files changed, 214 insertions(+), 232 deletions(-)
>
> --
> 2.49.0.472.ge94155a9ec-goog
>