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Subject: [PATCH v2 07/11] perf docs: extend stat mode docs with info on
 --ctl-fd[-ack] options
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>
Cc:     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>
References: <d582cc3d-2302-c7e2-70d3-bc7ab6f628c3@linux.intel.com>
Organization: Intel Corp.
Message-ID: <fb7c1fb9-2f6b-eb4b-d256-51253b29b4ac@linux.intel.com>
Date:   Wed, 6 May 2020 21:22:55 +0300
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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.

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