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, 28 insertions, 0 deletions

diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index a7a2825356d6..198982109f0f 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -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;
+}