linux-kernel - Re: [PATCH] perf/core: fix parent pid/tid in task exit events

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Message-ID: <20200417184536.GK20730@hirez.programming.kicks-ass.net>
Date:   Fri, 17 Apr 2020 20:45:36 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     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@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Stephane Eranian <eranian@...gle.com>,
        KP Singh <kpsingh@...gle.com>
Subject: Re: [PATCH] perf/core: fix parent pid/tid in task exit events

On Fri, Apr 17, 2020 at 11:28:42AM -0700, Ian Rogers wrote:
> Current logic yields the child task as the parent.
> 
> Before:
> $ perf record bash -c "perf list > /dev/null"
> $ perf script -D |grep 'FORK\|EXIT'
> 4387036190981094 0x5a70 [0x30]: PERF_RECORD_FORK(10472:10472):(10470:10470)
> 4387036606207580 0xf050 [0x30]: PERF_RECORD_EXIT(10472:10472):(10472:10472)
> 4387036607103839 0x17150 [0x30]: PERF_RECORD_EXIT(10470:10470):(10470:10470)
>                                                    ^
>   Note the repeated values here -------------------/
> 
> After:
> 383281514043 0x9d8 [0x30]: PERF_RECORD_FORK(2268:2268):(2266:2266)
> 383442003996 0x2180 [0x30]: PERF_RECORD_EXIT(2268:2268):(2266:2266)
> 383451297778 0xb70 [0x30]: PERF_RECORD_EXIT(2266:2266):(2265:2265)
> 

Fixes: .... ?

> Reported-by: KP Singh <kpsingh@...gle.com>
> Signed-off-by: Ian Rogers <irogers@...gle.com>