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Commit c3043569 authored by Jaswinder Singh Rajput's avatar Jaswinder Singh Rajput Committed by Ingo Molnar
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perf stat: Micro-optimize the code: memcpy is only required if no event is selected and !null_run 



Set attrs and nr_counters if no event is selected and !null_run.

Setting of attrs should depend on number of counters,
so we need to memcpy only for sizeof(default_attrs)

Also set nr_counters as ARRAY_SIZE(default_attrs) in place of
hardcoded value.

Signed-off-by: default avatarJaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1246126749.32198.16.camel@hpdv5.satnam>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6e750a8f

tools/perf/builtin-stat.c

+6 −5
Original line number Diff line number Diff line
@@ -46,7 +46,7 @@ 
#include <sys/prctl.h>

#include <math.h>



static struct perf_counter_attr default_attrs[MAX_COUNTERS] = {

static struct perf_counter_attr default_attrs[] = {



  { .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_TASK_CLOCK	},

  { .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_CONTEXT_SWITCHES},
@@ -477,16 +477,17 @@ int cmd_stat(int argc, const char **argv, const char *prefix) 
{

	int status;



	memcpy(attrs, default_attrs, sizeof(attrs));



	argc = parse_options(argc, argv, options, stat_usage, 0);

	if (!argc)

		usage_with_options(stat_usage, options);

	if (run_count <= 0 || run_count > MAX_RUN)

		usage_with_options(stat_usage, options);



	if (!null_run && !nr_counters)

		nr_counters = 8;

	/* Set attrs and nr_counters if no event is selected and !null_run */

	if (!null_run && !nr_counters) {

		memcpy(attrs, default_attrs, sizeof(default_attrs));

		nr_counters = ARRAY_SIZE(default_attrs);

	}



	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);

	assert(nr_cpus <= MAX_NR_CPUS);