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Commit 0cfb7a13 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perf stat: Add -n/--null option to run without counters 



Allow a no-counters run. This can be useful to measure just
elapsed wall-clock time - or to assess the raw overhead of perf
stat itself, without running any counters.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent fde953c1

tools/perf/builtin-stat.c

+4 −1
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ static int run_count = 1; 
static int			inherit				=  1;

static int			scale				=  1;

static int			target_pid			= -1;

static int			null_run			=  0;



static int			fd[MAX_NR_CPUS][MAX_COUNTERS];
@@ -461,6 +462,8 @@ static const struct option options[] = { 
		    "be more verbose (show counter open errors, etc)"),

	OPT_INTEGER('r', "repeat", &run_count,

		    "repeat command and print average + stddev (max: 100)"),

	OPT_BOOLEAN('n', "null", &null_run,

		    "null run - dont start any counters"),

	OPT_END()

};
@@ -476,7 +479,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix) 
	if (run_count <= 0 || run_count > MAX_RUN)

		usage_with_options(stat_usage, options);



	if (!nr_counters)

	if (!null_run && !nr_counters)

		nr_counters = 8;



	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);