[PATCH V3 6/6] perf record: add option to set the number of thread for event synthesize

From: kan . liang
Date: Fri Oct 20 2017 - 16:11:20 EST


From: Kan Liang <Kan.liang@xxxxxxxxx>

Using UINT_MAX to indicate the default thread#, which is the number of
online CPU.

Signed-off-by: Kan Liang <Kan.liang@xxxxxxxxx>
---
tools/perf/Documentation/perf-record.txt | 4 ++++
tools/perf/builtin-record.c | 10 +++++++++-
2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 68a1ffb..f759dc4 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -483,6 +483,10 @@ config terms. For example: 'cycles/overwrite/' and 'instructions/no-overwrite/'.

Implies --tail-synthesize.

+--num-thread-synthesize::
+The number of threads to run event synthesize.
+By default, the number of threads equals to the online CPU number.
+
SEE ALSO
--------
linkperf:perf-stat[1], linkperf:perf-list[1]
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 283fc21..4b65ebd 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -82,6 +82,7 @@ struct record {
struct switch_output switch_output;
unsigned long long samples;
struct perf_data_file *synthesized_file;
+ unsigned int nr_threads_synthesize;
};

static volatile int auxtrace_record__snapshot_started;
@@ -707,10 +708,14 @@ static int record__multithread_synthesize(struct record *rec,
struct perf_tool *tool,
struct record_opts *opts)
{
- int i, j, err, nr_thread = sysconf(_SC_NPROCESSORS_ONLN);
+ int i, j, err, nr_thread;
int fd_from, fd_to;
struct stat st;

+ if (rec->nr_threads_synthesize == UINT_MAX)
+ nr_thread = sysconf(_SC_NPROCESSORS_ONLN);
+ else
+ nr_thread = rec->nr_threads_synthesize;
again:
/* multithreading synthesize is only available for cpu monitoring */
if (target__has_task(&opts->target) || (nr_thread <= 1))
@@ -1530,6 +1535,7 @@ static struct record record = {
.mmap2 = perf_event__process_mmap2,
.ordered_events = true,
},
+ .nr_threads_synthesize = UINT_MAX,
};

const char record_callchain_help[] = CALLCHAIN_RECORD_HELP
@@ -1671,6 +1677,8 @@ static struct option __record_options[] = {
"signal"),
OPT_BOOLEAN(0, "dry-run", &dry_run,
"Parse options then exit"),
+ OPT_UINTEGER(0, "num-thread-synthesize", &record.nr_threads_synthesize,
+ "number of thread to run event synthesize"),
OPT_END()
};

--
2.7.4