linux-kernel - Re: [PATCH] perf bench: Fix numa report output code

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Date:   Wed, 20 Jun 2018 11:19:22 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH] perf bench: Fix numa report output code

Em Wed, Jun 20, 2018 at 11:40:36AM +0200, Jiri Olsa escreveu:
> Currently we can hit following assert when running numa bench:
> 
>   $ perf bench numa mem -p 3 -t 1 -P 512 -s 100 -zZ0cm --thp 1
>   perf: bench/numa.c:1577: __bench_numa: Assertion `!(!(((wait_stat) & 0x7f) == 0))' failed.
> 
> The assertion is correct, because we hit the SIGFPE in following line:
> 
>   Thread 2.2 "thread 0/0" received signal SIGFPE, Arithmetic exception.
>   [Switching to Thread 0x7fffd28c6700 (LWP 11750)]
>   0x000.. in worker_thread (__tdata=0x7.. ) at bench/numa.c:1257
>   1257 td->speed_gbs = bytes_done / (td->runtime_ns / NSEC_PER_SEC) / 1e9;
> 
> We don't check if the runtime is actually bigger than 1 second,
> and thus this might end up with zero division within FPU.
> 
> Adding the check to prevent this.
> 
> Link: http://lkml.kernel.org/n/tip-9y8n4x48mjbbcay73sq6nche@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>

thanks, applied to perf/urgent.

- Arnaldo