Commit 1d078ccb authored by Alexey Budankov's avatar Alexey Budankov Committed by Arnaldo Carvalho de Melo
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perf record: Introduce --control fd:ctl-fd[,ack-fd] options 



Introduce --control fd:ctl-fd[,ack-fd] options to pass open file
descriptors numbers from command line.

Extend perf-record.txt file with --control fd:ctl-fd[,ack-fd] options
description.

Document possible usage model introduced by --control fd:ctl-fd[,ack-fd]
options by providing example bash shell script.

Signed-off-by: default avatarAlexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: default avatarJiri Olsa <jolsa@redhat.com>
Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/8dc01e1a-3a80-3f67-5385-4bc7112b0dd3@linux.intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent acce0223

tools/perf/Documentation/perf-record.txt

+39 −0
Original line number Diff line number Diff line
@@ -627,6 +627,45 @@ option. The -e option and this one can be mixed and matched. Events 
can be grouped using the {} notation.

endif::HAVE_LIBPFM[]



--control fd:ctl-fd[,ack-fd]

Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,

'disable': disable events). Measurements can be started with events disabled using

--delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd 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               \

            --control fd:${ctl_fd},${ctl_fd_ack} \

            -- sleep 30 &

perf_pid=$!



sleep 5  && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})"

sleep 10 && echo 'disable' >&${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 $?





SEE ALSO

--------

linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-intel-pt[1]

tools/perf/builtin-record.c

+37 −0
Original line number Diff line number Diff line
@@ -1786,6 +1786,9 @@ static int __cmd_record(struct record *rec, int argc, const char **argv) 
		perf_evlist__start_workload(rec->evlist);

	}



	if (evlist__initialize_ctlfd(rec->evlist, opts->ctl_fd, opts->ctl_fd_ack))

		goto out_child;



	if (opts->initial_delay) {

		pr_info(EVLIST_DISABLED_MSG);

		if (opts->initial_delay > 0) {
@@ -1932,6 +1935,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv) 
		record__synthesize_workload(rec, true);



out_child:

	evlist__finalize_ctlfd(rec->evlist);

	record__mmap_read_all(rec, true);

	record__aio_mmap_read_sync(rec);
@@ -2281,6 +2285,33 @@ static int record__parse_mmap_pages(const struct option *opt, 
	return ret;

}



static int parse_control_option(const struct option *opt,

				const char *str,

				int unset __maybe_unused)

{

	char *comma = NULL, *endptr = NULL;

	struct record_opts *config = (struct record_opts *)opt->value;



	if (strncmp(str, "fd:", 3))

		return -EINVAL;



	config->ctl_fd = strtoul(&str[3], &endptr, 0);

	if (endptr == &str[3])

		return -EINVAL;



	comma = strchr(str, ',');

	if (comma) {

		if (endptr != comma)

			return -EINVAL;



		config->ctl_fd_ack = strtoul(comma + 1, &endptr, 0);

		if (endptr == comma + 1 || *endptr != '\0')

			return -EINVAL;

	}



	return 0;

}



static void switch_output_size_warn(struct record *rec)

{

	u64 wakeup_size = evlist__mmap_size(rec->opts.mmap_pages);
@@ -2417,6 +2448,8 @@ static struct record record = { 
		},

		.mmap_flush          = MMAP_FLUSH_DEFAULT,

		.nr_threads_synthesize = 1,

		.ctl_fd              = -1,

		.ctl_fd_ack          = -1,

	},

	.tool = {

		.sample		= process_sample_event,
@@ -2618,6 +2651,10 @@ static struct option __record_options[] = { 
		"libpfm4 event selector. use 'perf list' to list available events",

		parse_libpfm_events_option),

#endif

	OPT_CALLBACK(0, "control", &record.opts, "fd:ctl-fd[,ack-fd]",

		     "Listen on ctl-fd descriptor for command to control measurement ('enable': enable events, 'disable': disable events).\n"

		     "\t\t\t  Optionally send control command completion ('ack\\n') to ack-fd descriptor.",

		      parse_control_option),

	OPT_END()

};

tools/perf/util/record.h

+2 −0
Original line number Diff line number Diff line
@@ -71,6 +71,8 @@ struct record_opts { 
	int	      mmap_flush;

	unsigned int  comp_level;

	unsigned int  nr_threads_synthesize;

	int	      ctl_fd;

	int	      ctl_fd_ack;

};



extern const char * const *record_usage;