From: Ian Rogers <irogers@google.com>
To: "Liang, Kan" <kan.liang@linux.intel.com>
Cc: weilin.wang@intel.com, Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Ze Gao <zegao2021@gmail.com>, Leo Yan <leo.yan@linux.dev>,
Ravi Bangoria <ravi.bangoria@amd.com>,
Dmitrii Dolgov <9erthalion6@gmail.com>,
Song Liu <song@kernel.org>, James Clark <james.clark@arm.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v1 0/3] Retirement latency perf stat support
Date: Fri, 26 Apr 2024 10:34:39 -0700 [thread overview]
Message-ID: <CAP-5=fX520Nvd7V_UNDn5yQV-o0-ADYNe7XqdjHUmRVtEC_5tw@mail.gmail.com> (raw)
In-Reply-To: <53dfaeae-b4eb-479e-938f-d0022c4f2416@linux.intel.com>
On Fri, Apr 26, 2024 at 10:22 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>
> On 2024-04-25 6:34 p.m., Ian Rogers wrote:
> > Support 'R' as a retirement latency modifier on events. When present
> > the evsel will fork perf record and perf report commands, parsing the
> > perf report output as the count value. The intent is to do something
> > similar to Weilin's series:
> > https://lore.kernel.org/lkml/20240402214436.1409476-1-weilin.wang@intel.com/
> >
> > While the 'R' and the retirement latency are Intel specific, in the
> > future I can imagine more evsel like commands that require child
> > processes. We can make the logic more generic at that point.
> >
>
> I think in generic what we want is the weight/latency information of the
> event. 'W' is already occupied by the weak group. Maybe 'L' is a more
> generic name than 'R'. With the event modifier, perf collects and report
> the weight/latency information of the event in a perf stat command.
>
> Not just changing the evsel, I think a proper output is still required.
> It's possible that an end user can use it without metrics. E.g.,
> perf stat -e cycles,instructions:L
> A possible generic output maybe
>
> 1,931,099,931 cycles
> 801,826,458 instructions # Avg Weight1 1000
> # Avg Weight2 800
> # Avg Weight3 500
I think this is good but we need to work toward it. This change is
opening a separate perf record per CPU, we should really open one perf
record and then read each counter separately in the perf report
output. We shouldn't really fork a perf record, we should gather
multiple weights, and so on.. There isn't a notion in the current
counts abstraction that you have multiple counts, and that will need
feeding through into all the aggregation code.
Thanks,
Ian
> Thanks,
> Kan
>
> > The code is untested on hardware that supports retirement latency, and
> > with metrics with retirement latency in them. The record is also of
> > sleep and various things need tweaking but I think v1 is good enough
> > for people to give input.
> >
> > The first patch stops opening a dummy event for tool events. I came
> > across this while looking into the issue and we can likely just pick
> > it first. I kept it in the series for cleanliness sake.
> >
> > The code has benefitted greatly from Weilin's work and Namhyung's
> > great review input.
> >
> > Ian Rogers (3):
> > perf evsel: Don't open tool events
> > perf parse-events: Add a retirement latency modifier
> > perf evsel: Add retirement latency event support
> >
> > tools/perf/util/evsel.c | 186 ++++++++++++++++++++++++++++++++-
> > tools/perf/util/evsel.h | 4 +
> > tools/perf/util/parse-events.c | 2 +
> > tools/perf/util/parse-events.h | 1 +
> > tools/perf/util/parse-events.l | 3 +-
> > 5 files changed, 192 insertions(+), 4 deletions(-)
> >
prev parent reply other threads:[~2024-04-26 17:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-25 22:34 [RFC PATCH v1 0/3] Retirement latency perf stat support Ian Rogers
2024-04-25 22:34 ` [RFC PATCH v1 1/3] perf evsel: Don't open tool events Ian Rogers
2024-04-25 22:34 ` [RFC PATCH v1 2/3] perf parse-events: Add a retirement latency modifier Ian Rogers
2024-04-25 22:34 ` [RFC PATCH v1 3/3] perf evsel: Add retirement latency event support Ian Rogers
2024-04-25 22:41 ` [RFC PATCH v1 0/3] Retirement latency perf stat support Ian Rogers
2024-04-26 17:22 ` Liang, Kan
2024-04-26 17:34 ` Ian Rogers [this message]
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