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From:   Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Date:   Wed, 6 May 2020 17:22:35 -0300
To:     Alexey Budankov <alexey.budankov@linux.intel.com>
Cc:     Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Andi Kleen <ak@linux.intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 07/11] perf docs: extend stat mode docs with info on
 --ctl-fd[-ack] options
Message-ID: <20200506202235.GG9893@kernel.org>
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Em Wed, May 06, 2020 at 09:22:55PM +0300, Alexey Budankov escreveu:
> 
> Extend perf-stat.txt file with --ctl-fd[-ack] options description.
> Document possible usage model introduced by --ctl-fd[-ack] options
> by providing example bash shell script.

Please update the docs in the same patch that introduces the options
being documented.

- Arnaldo

> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
> ---
>  tools/perf/Documentation/perf-stat.txt | 40 ++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
> index 3fb5028aef08..19ed53e08294 100644
> --- a/tools/perf/Documentation/perf-stat.txt
> +++ b/tools/perf/Documentation/perf-stat.txt
> @@ -164,6 +164,46 @@ with it.  --append may be used here.  Examples:
>       3>results  perf stat --log-fd 3          -- $cmd
>       3>>results perf stat --log-fd 3 --append -- $cmd
>  
> +--ctl-fd::
> +--ctl-fd-ack::
> +
> +Listen on ctl-fd descriptor for command to control measurement ('e': enable events,
> +'d': disable events). Optionally send control command completion ('a') to fd-ack
> +descriptor to synchronize with the controlling process. Example of bash shell script
> +to enable and disable events during measurements:
> +
> +#!/bin/bash
> +
> +ctl_dir=/tmp/
> +
> +ctl_fifo=${ctl_dir}perf_ctl.fifo
> +test -p ${ctl_fifo} && unlink ${ctl_fifo}
> +mkfifo ${ctl_fifo}
> +exec {ctl_fd}<>${ctl_fifo}
> +
> +ctl_ack_fifo=${ctl_dir}perf_ctl_ack.fifo
> +test -p ${ctl_ack_fifo} && unlink ${ctl_ack_fifo}
> +mkfifo ${ctl_ack_fifo}
> +exec {ctl_fd_ack}<>${ctl_ack_fifo}
> +
> +perf stat -D -1 -e cpu-cycles -a -I 1000                \
> +          --ctl-fd ${ctl_fd} --ctl-fd-ack ${ctl_fd_ack} \
> +          -- sleep 30 &
> +perf_pid=$!
> +
> +sleep 5  && echo 'e' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})"
> +sleep 10 && echo 'd' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "disabled(${d1})"
> +
> +exec {ctl_fd_ack}>&-
> +unlink ${ctl_ack_fifo}
> +
> +exec {ctl_fd}>&-
> +unlink ${ctl_fifo}
> +
> +wait -n ${perf_pid}
> +exit $?
> +
> +
>  --pre::
>  --post::
>  	Pre and post measurement hooks, e.g.:
> -- 
> 2.24.1
> 
> 

-- 

- Arnaldo