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From:   Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Date:   Wed, 6 May 2020 17:27:19 -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 11/11] perf docs: extend record mode docs with info on
 --ctl-fd[-ack] options
Message-ID: <20200506202719.GJ9893@kernel.org>
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Em Wed, May 06, 2020 at 09:30:50PM +0300, Alexey Budankov escreveu:
> 
> Extend perf-record.txt file with --ctl-fd[-ack] options description.
> Document possible usage model introduced by --ctl-fd[-ack] options
> by providing example bash shell script.

Ditto, combine this patch with the one that introduces these options.
 
> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
> ---
>  tools/perf/Documentation/perf-record.txt | 39 ++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
> index 561ef55743e2..eabb00ed2f5d 100644
> --- a/tools/perf/Documentation/perf-record.txt
> +++ b/tools/perf/Documentation/perf-record.txt
> @@ -613,6 +613,45 @@ appended unit character - B/K/M/G
>  	The number of threads to run when synthesizing events for existing processes.
>  	By default, the number of threads equals 1.
>  
> +--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 record -D -1 -e cpu-cycles -a                        \
> +            --ctl-fd ${ctl_fd} --ctl-fd-ack ${ctl_fd_ack} \
> +            -- sleep 30 &
> +perf_pid=$!
> +
> +sleep 5  && echo 'e' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "resumed(${e1})"
> +sleep 10 && echo 'd' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "paused(${d1})"
> +
> +exec {ctl_fd_ack}>&-
> +unlink ${ctl_ack_fifo}
> +
> +exec {ctl_fd}>&-
> +unlink ${ctl_fifo}
> +
> +wait -n ${perf_pid}
> +exit $?
> +
> +
>  SEE ALSO
>  --------
>  linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-intel-pt[1]
> -- 
> 2.24.1
> 
> 

-- 

- Arnaldo