Commit 991ae4eb authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
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perf tools: Allow to enable/disable events via control file 



Adding new control events to enable/disable specific event.
The interface string for control file are:

  'enable <EVENT NAME>'
  'disable <EVENT NAME>'

when received the command, perf will scan the current evlist
for <EVENT NAME> and if found it's enabled/disabled.

Example session:

  terminal 1:
    # mkfifo control ack perf.pipe
    # perf record --control=fifo:control,ack -D -1 --no-buffering -e 'sched:*' -o - > perf.pipe

  terminal 2:
    # cat perf.pipe | perf --no-pager script -i -

  terminal 1:
    Events disabled

  NOTE Above message will show only after read side of the pipe ('>')
  is started on 'terminal 2'. The 'terminal 1's bash does not execute
  perf before that, hence the delyaed perf record message.

  terminal 3:
    # echo 'enable sched:sched_process_fork' > control

  terminal 1:
    event sched:sched_process_fork enabled

  terminal 2:
    bash 33349 [034] 149587.674295: sched:sched_process_fork: comm=bash pid=33349 child_comm=bash child_pid=34056
    bash 33349 [034] 149588.239521: sched:sched_process_fork: comm=bash pid=33349 child_comm=bash child_pid=34057

  terminal 3:
    # echo 'enable sched:sched_wakeup_new' > control

  terminal 1:
    event sched:sched_wakeup_new enabled

  terminal 2:
    bash 33349 [034] 149632.228023: sched:sched_process_fork: comm=bash pid=33349 child_comm=bash child_pid=34059
    bash 33349 [034] 149632.228050:   sched:sched_wakeup_new: bash:34059 [120] success=1 CPU:036
    bash 33349 [034] 149633.950005: sched:sched_process_fork: comm=bash pid=33349 child_comm=bash child_pid=34060
    bash 33349 [034] 149633.950030:   sched:sched_wakeup_new: bash:34060 [120] success=1 CPU:036

Committer testing:

If I use 'sched:*' and then enable all events, I can't get 'perf record'
to react to further commands, so I tested it with:

  [root@five ~]# perf record --control=fifo:control,ack -D -1 --no-buffering -e 'sched:sched_process_*' -o - > perf.pipe
  Events disabled
  Events enabled
  Events disabled

And then it works as expected, so we need to fix this pre-existing
problem.

Another issue, we need to check if a event is already enabled or
disabled and change the message to be clearer, i.e.:

  [root@five ~]# perf record --control=fifo:control,ack -D -1 --no-buffering -e 'sched:sched_process_*' -o - > perf.pipe
  Events disabled

If we receive a 'disable' command, then it should say:

  [root@five ~]# perf record --control=fifo:control,ack -D -1 --no-buffering -e 'sched:sched_process_*' -o - > perf.pipe
  Events disabled
  Events already disabled

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20201226232038.390883-2-jolsa@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent e8b2db07

tools/perf/Documentation/perf-record.txt

+5 −3
Original line number Diff line number Diff line
@@ -648,6 +648,8 @@ Listen on ctl-fd descriptor for command to control measurement. 
Available commands:

  'enable'       : enable events

  'disable'      : disable events

  'enable name'  : enable event 'name'

  'disable name' : disable event 'name'

  'snapshot'     : AUX area tracing snapshot).



Measurements can be started with events disabled using --delay=-1 option. Optionally

tools/perf/builtin-record.c

+2 −6
Original line number Diff line number Diff line
@@ -1938,18 +1938,14 @@ static int __cmd_record(struct record *rec, int argc, const char **argv) 


		if (evlist__ctlfd_process(rec->evlist, &cmd) > 0) {

			switch (cmd) {

			case EVLIST_CTL_CMD_ENABLE:

				pr_info(EVLIST_ENABLED_MSG);

				break;

			case EVLIST_CTL_CMD_DISABLE:

				pr_info(EVLIST_DISABLED_MSG);

				break;

			case EVLIST_CTL_CMD_SNAPSHOT:

				hit_auxtrace_snapshot_trigger(rec);

				evlist__ctlfd_ack(rec->evlist);

				break;

			case EVLIST_CTL_CMD_ACK:

			case EVLIST_CTL_CMD_UNSUPPORTED:

			case EVLIST_CTL_CMD_ENABLE:

			case EVLIST_CTL_CMD_DISABLE:

			default:

				break;

			}

tools/perf/builtin-stat.c

+0 −2
Original line number Diff line number Diff line
@@ -611,14 +611,12 @@ static void process_evlist(struct evlist *evlist, unsigned int interval) 
	if (evlist__ctlfd_process(evlist, &cmd) > 0) {

		switch (cmd) {

		case EVLIST_CTL_CMD_ENABLE:

			pr_info(EVLIST_ENABLED_MSG);

			if (interval)

				process_interval();

			break;

		case EVLIST_CTL_CMD_DISABLE:

			if (interval)

				process_interval();

			pr_info(EVLIST_DISABLED_MSG);

			break;

		case EVLIST_CTL_CMD_SNAPSHOT:

		case EVLIST_CTL_CMD_ACK:

tools/perf/util/evlist.c

+60 −3
Original line number Diff line number Diff line
@@ -1957,6 +1957,64 @@ int evlist__ctlfd_ack(struct evlist *evlist) 
	return err;

}



static int get_cmd_arg(char *cmd_data, size_t cmd_size, char **arg)

{

	char *data = cmd_data + cmd_size;



	/* no argument */

	if (!*data)

		return 0;



	/* there's argument */

	if (*data == ' ') {

		*arg = data + 1;

		return 1;

	}



	/* malformed */

	return -1;

}



static int evlist__ctlfd_enable(struct evlist *evlist, char *cmd_data, bool enable)

{

	struct evsel *evsel;

	char *name;

	int err;



	err = get_cmd_arg(cmd_data,

			  enable ? sizeof(EVLIST_CTL_CMD_ENABLE_TAG) - 1 :

				   sizeof(EVLIST_CTL_CMD_DISABLE_TAG) - 1,

			  &name);

	if (err < 0) {

		pr_info("failed: wrong command\n");

		return -1;

	}



	if (err) {

		evsel = evlist__find_evsel_by_str(evlist, name);

		if (evsel) {

			if (enable)

				evlist__enable_evsel(evlist, name);

			else

				evlist__disable_evsel(evlist, name);

			pr_info("Event %s %s\n", evsel->name,

				enable ? "enabled" : "disabled");

		} else {

			pr_info("failed: can't find '%s' event\n", name);

		}

	} else {

		if (enable) {

			evlist__enable(evlist);

			pr_info(EVLIST_ENABLED_MSG);

		} else {

			evlist__disable(evlist);

			pr_info(EVLIST_DISABLED_MSG);

		}

	}



	return 0;

}



int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd)

{

	int err = 0;
@@ -1973,10 +2031,9 @@ int evlist__ctlfd_process(struct evlist *evlist, enum evlist_ctl_cmd *cmd) 
		if (err > 0) {

			switch (*cmd) {

			case EVLIST_CTL_CMD_ENABLE:

				evlist__enable(evlist);

				break;

			case EVLIST_CTL_CMD_DISABLE:

				evlist__disable(evlist);

				err = evlist__ctlfd_enable(evlist, cmd_data,

							   *cmd == EVLIST_CTL_CMD_ENABLE);

				break;

			case EVLIST_CTL_CMD_SNAPSHOT:

				break;