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

[Jiri Olsa <jolsa@redhat.com>]

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@windriver.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@kernel.org>

thanks,
jirka