Messages in this thread | | | Date | Fri, 26 Apr 2024 13:22:05 -0400 | Subject | Re: [RFC PATCH v1 0/3] Retirement latency perf stat support | From | "Liang, Kan" <> |
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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
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(-) >
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