linux-kernel - Re: [PATCH v1 0/3] perf list: Remove duplicate PMUs

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Date:   Wed, 2 Aug 2023 12:15:04 +0100
From:   John Garry <john.g.garry@...cle.com>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 0/3] perf list: Remove duplicate PMUs

On 01/08/2023 18:39, Ian Rogers wrote:
>>> I didn't write this behavior, it has pre-existed my contributions. I'm
>>> hoping to change the perf list behavior as we're seeing large server
>>> systems with getting on toward 100 PMUs, the events are replicated for
>>> each one and the perf list and testing behaviors are somewhat
>>> exploding in size.
>> Sure, that is why I was advised PMU kernel drivers event names to be
>> unique per PMU, so that we can add an event alias in a JSON and then
>> kernel events are matched and removed from perf list.
>>
>> I suppose that your changes are an alternative to the problem of
>> mushrooming kernel event list.
> Thanks John, yep this is going after that problem. Could I get a
> reviewed/acked/tested-by for these changes?

I'll try to help.

So we have:

Before:
```
$ perf list
...
   uncore_imc_free_running_0/data_read/               [Kernel PMU event]
   uncore_imc_free_running_0/data_total/              [Kernel PMU event]
   uncore_imc_free_running_0/data_write/              [Kernel PMU event]
   uncore_imc_free_running_1/data_read/               [Kernel PMU event]
   uncore_imc_free_running_1/data_total/              [Kernel PMU event]
   uncore_imc_free_running_1/data_write/              [Kernel PMU event]
```

After:
```
$ perf list
...
   uncore_imc_free_running/data_read/                 [Kernel PMU event]
   uncore_imc_free_running/data_total/                [Kernel PMU event]
   uncore_imc_free_running/data_write/                [Kernel PMU event]
```
How about keep listing uncore_imc_free_running_0 and the rest for perf 
list -v? Or something like that.

I find that the perf tool has lots of veiled tricks in terms of usage 
and describing events available and how to use them.

Thanks,
John