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: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri 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: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 39 insertions, 9 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 0263e383332f..41bb884f5a74 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -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");
 
-	err = perf_event__synthesize_cgroups(tool, process_synthesized_event,
-					     machine);
-	if (err < 0)
-		pr_warning("Couldn't synthesize cgroup 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;
 	}
 
-	err = __machine__synthesize_threads(machine, tool, &opts->target,
-					    rec->evlist->core.threads,
-					    f, true, opts->sample_address,
-					    rec->opts.nr_threads_synthesize);
+	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, 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()
 };