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SubjectRe: [PATCH -tip] perf stat: memcpy is only required if no event is selected and !null_run
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If You want can also add Impact Line.

Impact: Speedup, reduce binary size.


On Sat, 2009-06-27 at 23:49 +0530, Jaswinder Singh Rajput wrote:
> 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)
>
> and set nr_counters as ARRAY_SIZE(default_attrs) in place of hardcoded value
>
> Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
> ---
> tools/perf/builtin-stat.c | 11 ++++++-----
> 1 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 3840a70..3e5ea4e 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -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);



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