linux-kernel - Re: [PATCH v5] perf record: Add support for limit perf output file size

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Date:   Fri, 1 Nov 2019 09:13:00 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     jsun4 <jiwei.sun@...driver.com>
Cc:     acme@...hat.com, arnaldo.melo@...il.com,
        linux-kernel@...r.kernel.org, alexander.shishkin@...ux.intel.com,
        mpetlan@...hat.com, namhyung@...nel.org, a.p.zijlstra@...llo.nl,
        adrian.hunter@...el.com, Richard.Danter@...driver.com,
        jiwei.sun.bj@...com
Subject: Re: [PATCH v5] perf record: Add support for limit perf output file
 size

On Tue, Oct 22, 2019 at 04:09:01PM +0800, jsun4 wrote:
> The patch adds a new option to limit the output file size, then based
> on it, we can create a wrapper of the perf command that uses the option
> to avoid exhausting the disk space by the unconscious user.
> 
> In order to make the perf.data parsable, we just limit the sample data
> size, since the perf.data consists of many headers and sample data and
> other data, the actual size of the recorded file will bigger than the
> setting value.
> 
> Testing it:
> 
>  # ./perf record -a -g --max-size=10M
>  Couldn't synthesize bpf events.
>  [ perf record: perf size limit reached (10249 KB), stopping session ]
>  [ perf record: Woken up 32 times to write data ]
>  [ perf record: Captured and wrote 10.133 MB perf.data (71964 samples) ]
> 
>  # ls -lh perf.data
>  -rw------- 1 root root 11M Oct 22 14:32 perf.data
> 
>  # ./perf record -a -g --max-size=10K
>  [ perf record: perf size limit reached (10 KB), stopping session ]
>  Couldn't synthesize bpf events.
>  [ perf record: Woken up 0 times to write data ]
>  [ perf record: Captured and wrote 1.546 MB perf.data (69 samples) ]
> 
>  # ls -l perf.data
>  -rw------- 1 root root 1626952 Oct 22 14:36 perf.data
> 
> Signed-off-by: Jiwei Sun <jiwei.sun@...driver.com>
> ---
> v5 changes:
>   - Change the output format like [ perf record: perf size limit XX ]
>   - change the killing perf way from "raise(SIGTERM)" to set "done == 1"

Acked-by: Jiri Olsa <jolsa@...nel.org>

thanks,
jirka