linux-kernel - [PATCH v1 8/8] perf docs: extend record mode docs with info on --ctl-fd[-ack] options

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Date:   Fri, 27 Mar 2020 11:51:08 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@...hat.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH v1 8/8] perf docs: extend record mode docs with info on
 --ctl-fd[-ack] options


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.

Signed-off-by: Alexey Budankov <alexey.budankov@...ux.intel.com>
---
 tools/perf/Documentation/perf-record.txt | 37 ++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 7f4db7592467..939e8eb864fe 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -587,6 +587,43 @@ Make a copy of /proc/kcore and place it into a directory with the perf data file
 Limit the sample data max size, <size> is expected to be a number with
 appended unit character - B/K/M/G
 
+--ctl-fd::
+--ctl-fd-ack::
+Listen on ctl-fd descriptor for command to control measurement ('r': resume,
+'p': pause). Optionally send control command completion ('a') to fd-ack descriptor
+to synchronize with the controlling process. Example of bash shell script
+to resume and pause 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 'r' >&${ctl_fd} && read -u ${ctl_fd_ack} r1 && echo "resumed(${r1})"
+sleep 10 && echo 'p' >&${ctl_fd} && read -u ${ctl_fd_ack} p1 && echo "paused(${p1})"
+
+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