linux-kernel - Re: [PATCHSET 0/5] perf tools: Show per-event lost sample count (v2)

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Date:   Fri, 2 Sep 2022 20:44:25 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Namhyung Kim <namhyung@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        linux-perf-users@...r.kernel.org
Subject: Re: [PATCHSET 0/5] perf tools: Show per-event lost sample count (v2)

On 1/09/22 22:57, Namhyung Kim wrote:
> Hello,
> 
> Now we have PERF_FORMAT_LOST support, add it to perf record and report so that
> it can show number of lost samples per event.  This can be useful if you want
> to reconstruct number of events from the samples like when using -c option.
> 
> Changes in v2)
>  * fix id_hdr_size calculation  (Adrian)
>  * fix a memory leak
>  * display lost samples even if no samples
>  
>  
> Currently it adds PERF_RECORD_LOST_SAMPLES at the end of perf data after reading
> event values by read(2).  The perf record unconditionally sets the lost bit if
> the kernel supports it.  Users can see the number with `perf report --stat`.
> 
> You can get the code from 'perf/report-lost-v2' brach on
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
> 
> Thanks,
> Namhyung
> 
> Namhyung Kim (5):
>   perf tools: Print LOST read format in the verbose mode
>   perf record: Set PERF_FORMAT_LOST by default
>   perf record: Read and inject LOST_SAMPLES events
>   perf hist: Add nr_lost_samples to hist_stats
>   perf report: Show per-event LOST SAMPLES stat

Reviewed-by: Adrian Hunter <adrian.hunter@...el.com>