Commit 41b740b6 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf record: Add --synth option 



Add an option to control the synthesizing behavior.

    --synth <no|all|task|mmap|cgroup>
                      Fine-tune event synthesis: default=all

This can be useful when we know it doesn't need some synthesis like
in a specific usecase and/or when using pipe:

  $ perf record -a --all-cgroups --synth cgroup -o- sleep 1 | \
  > perf report -i- -s cgroup

Committer notes:

Added a clarification to the man page entry for --synth that this is
about pre-existing threads.

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https //lore.kernel.org/r/20210811044658.1313391-2-namhyung@kernel.org
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 84111b9c

tools/perf/Documentation/perf-record.txt

+16 −0
Original line number Diff line number Diff line
@@ -596,6 +596,22 @@ options. 
'perf record --dry-run -e' can act as a BPF script compiler if llvm.dump-obj

in config file is set to true.



--synth=TYPE::

Collect and synthesize given type of events (comma separated).  Note that

this option controls the synthesis from the /proc filesystem which represent

task status for pre-existing threads.



Kernel (and some other) events are recorded regardless of the

choice in this option.  For example, --synth=no would have MMAP events for

kernel and modules.



Available types are:

  'task'    - synthesize FORK and COMM events for each task

  'mmap'    - synthesize MMAP events for each process (implies 'task')

  'cgroup'  - synthesize CGROUP events for each cgroup

  'all'     - synthesize all events (default)

  'no'      - do not synthesize any of the above events



--tail-synthesize::

Instead of collecting non-sample events (for example, fork, comm, mmap) at

the beginning of record, collect them during finalizing an output file.

tools/perf/builtin-record.c

+39 −9
Original line number Diff line number Diff line
@@ -1255,6 +1255,7 @@ static int record__synthesize_workload(struct record *rec, bool tail) 
{

	int err;

	struct perf_thread_map *thread_map;

	bool needs_mmap = rec->opts.synth & PERF_SYNTH_MMAP;



	if (rec->opts.tail_synthesize != tail)

		return 0;
@@ -1266,7 +1267,7 @@ static int record__synthesize_workload(struct record *rec, bool tail) 
	err = perf_event__synthesize_thread_map(&rec->tool, thread_map,

						 process_synthesized_event,

						 &rec->session->machines.host,

						 true,

						 needs_mmap,

						 rec->opts.sample_address);

	perf_thread_map__put(thread_map);

	return err;
@@ -1471,20 +1472,26 @@ static int record__synthesize(struct record *rec, bool tail) 
	if (err < 0)

		pr_warning("Couldn't synthesize bpf events.\n");



	if (rec->opts.synth & PERF_SYNTH_CGROUP) {

		err = perf_event__synthesize_cgroups(tool, process_synthesized_event,

						     machine);

		if (err < 0)

			pr_warning("Couldn't synthesize cgroup events.\n");

	}



	if (rec->opts.nr_threads_synthesize > 1) {

		perf_set_multithreaded();

		f = process_locked_synthesized_event;

	}



	if (rec->opts.synth & PERF_SYNTH_TASK) {

		bool needs_mmap = rec->opts.synth & PERF_SYNTH_MMAP;



		err = __machine__synthesize_threads(machine, tool, &opts->target,

						    rec->evlist->core.threads,

					    f, true, opts->sample_address,

						    f, needs_mmap, opts->sample_address,

						    rec->opts.nr_threads_synthesize);

	}



	if (rec->opts.nr_threads_synthesize > 1)

		perf_set_singlethreaded();
@@ -2393,6 +2400,26 @@ static int process_timestamp_boundary(struct perf_tool *tool, 
	return 0;

}



static int parse_record_synth_option(const struct option *opt,

				     const char *str,

				     int unset __maybe_unused)

{

	struct record_opts *opts = opt->value;

	char *p = strdup(str);



	if (p == NULL)

		return -1;



	opts->synth = parse_synth_opt(p);

	free(p);



	if (opts->synth < 0) {

		pr_err("Invalid synth option: %s\n", str);

		return -1;

	}

	return 0;

}



/*

 * XXX Ideally would be local to cmd_record() and passed to a record__new

 * because we need to have access to it in record__exit, that is called
@@ -2418,6 +2445,7 @@ static struct record record = { 
		.nr_threads_synthesize = 1,

		.ctl_fd              = -1,

		.ctl_fd_ack          = -1,

		.synth               = PERF_SYNTH_ALL,

	},

	.tool = {

		.sample		= process_sample_event,
@@ -2633,6 +2661,8 @@ static struct option __record_options[] = { 
		     "\t\t\t  Optionally send control command completion ('ack\\n') to ack-fd descriptor.\n"

		     "\t\t\t  Alternatively, ctl-fifo / ack-fifo will be opened and used as ctl-fd / ack-fd.",

		      parse_control_option),

	OPT_CALLBACK(0, "synth", &record.opts, "no|all|task|mmap|cgroup",

		     "Fine-tune event synthesis: default=all", parse_record_synth_option),

	OPT_END()

};

tools/perf/util/record.h

+1 −0
Original line number Diff line number Diff line
@@ -77,6 +77,7 @@ struct record_opts { 
	int	      ctl_fd;

	int	      ctl_fd_ack;

	bool	      ctl_fd_close;

	int	      synth;

};



extern const char * const *record_usage;

tools/perf/util/synthetic-events.c

+28 −0
Original line number Diff line number Diff line
@@ -2237,3 +2237,31 @@ int perf_event__synthesize_for_pipe(struct perf_tool *tool, 


	return ret;

}



int parse_synth_opt(char *synth)

{

	char *p, *q;

	int ret = 0;



	if (synth == NULL)

		return -1;



	for (q = synth; (p = strsep(&q, ",")); p = q) {

		if (!strcasecmp(p, "no") || !strcasecmp(p, "none"))

			return 0;



		if (!strcasecmp(p, "all"))

			return PERF_SYNTH_ALL;



		if (!strcasecmp(p, "task"))

			ret |= PERF_SYNTH_TASK;

		else if (!strcasecmp(p, "mmap"))

			ret |= PERF_SYNTH_TASK | PERF_SYNTH_MMAP;

		else if (!strcasecmp(p, "cgroup"))

			ret |= PERF_SYNTH_CGROUP;

		else

			return -1;

	}



	return ret;

}

tools/perf/util/synthetic-events.h

+12 −0
Original line number Diff line number Diff line
@@ -27,6 +27,18 @@ struct target; 


union perf_event;



enum perf_record_synth {

	PERF_SYNTH_TASK		= 1 << 0,

	PERF_SYNTH_MMAP		= 1 << 1,

	PERF_SYNTH_CGROUP	= 1 << 2,



	/* last element */

	PERF_SYNTH_MAX		= 1 << 3,

};

#define PERF_SYNTH_ALL  (PERF_SYNTH_MAX - 1)



int parse_synth_opt(char *str);



typedef int (*perf_event__handler_t)(struct perf_tool *tool, union perf_event *event,

				     struct perf_sample *sample, struct machine *machine);