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Date: Fri, 19 Mar 2021 10:01:05 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Changbin Du <changbin.du@...il.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Jiri Olsa <jolsa@...hat.com>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v2] perf stat: improve readability of shadow stats
Hello,
On Mon, Mar 15, 2021 at 11:31 PM Changbin Du <changbin.du@...il.com> wrote:
>
> This adds function convert_unit_double() and selects appropriate
> unit for shadow stats between K/M/G.
>
> $ sudo ./perf stat -a -- sleep 1
>
> Before: Unit 'M' is selected even the number is very small.
> Performance counter stats for 'system wide':
>
> 4,003.06 msec cpu-clock # 3.998 CPUs utilized
> 16,179 context-switches # 0.004 M/sec
> 161 cpu-migrations # 0.040 K/sec
> 4,699 page-faults # 0.001 M/sec
> 6,135,801,925 cycles # 1.533 GHz (83.21%)
> 5,783,308,491 stalled-cycles-frontend # 94.26% frontend cycles idle (83.21%)
> 4,543,694,050 stalled-cycles-backend # 74.05% backend cycles idle (66.49%)
> 4,720,130,587 instructions # 0.77 insn per cycle
> # 1.23 stalled cycles per insn (83.28%)
> 753,848,078 branches # 188.318 M/sec (83.61%)
> 37,457,747 branch-misses # 4.97% of all branches (83.48%)
>
> 1.001283725 seconds time elapsed
>
> After:
> $ sudo ./perf stat -a -- sleep 2
>
> Performance counter stats for 'system wide':
>
> 8,005.52 msec cpu-clock # 3.999 CPUs utilized
> 10,715 context-switches # 1.338 K/sec
> 785 cpu-migrations # 98.057 /sec
> 102 page-faults # 12.741 /sec
> 1,948,202,279 cycles # 0.243 GHz
> 2,816,470,932 stalled-cycles-frontend # 144.57% frontend cycles idle
> 2,661,172,207 stalled-cycles-backend # 136.60% backend cycles idle
> 464,172,105 instructions # 0.24 insn per cycle
> # 6.07 stalled cycles per insn
> 91,567,662 branches # 11.438 M/sec
> 7,756,054 branch-misses # 8.47% of all branches
>
> 2.002040043 seconds time elapsed
>
> Signed-off-by: Changbin Du <changbin.du@...il.com>
Acked-by: Namhyung Kim <namhyung@...nel.org>
Thanks,
Namhyung
>
> v2:
> o do not change 'sec' to 'cpu-sec'.
> o use convert_unit_double to implement convert_unit.
> ---
> tools/perf/util/stat-shadow.c | 16 +++++++---------
> tools/perf/util/units.c | 21 ++++++++++++++-------
> tools/perf/util/units.h | 1 +
> 3 files changed, 22 insertions(+), 16 deletions(-)
>
> diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
> index 6ccf21a72f06..3f800e71126f 100644
> --- a/tools/perf/util/stat-shadow.c
> +++ b/tools/perf/util/stat-shadow.c
> @@ -9,6 +9,7 @@
> #include "expr.h"
> #include "metricgroup.h"
> #include "cgroup.h"
> +#include "units.h"
> #include <linux/zalloc.h>
>
> /*
> @@ -1270,18 +1271,15 @@ void perf_stat__print_shadow_stats(struct perf_stat_config *config,
> generic_metric(config, evsel->metric_expr, evsel->metric_events, NULL,
> evsel->name, evsel->metric_name, NULL, 1, cpu, out, st);
> } else if (runtime_stat_n(st, STAT_NSECS, cpu, &rsd) != 0) {
> - char unit = 'M';
> - char unit_buf[10];
> + char unit = ' ';
> + char unit_buf[10] = "/sec";
>
> total = runtime_stat_avg(st, STAT_NSECS, cpu, &rsd);
> -
> if (total)
> - ratio = 1000.0 * avg / total;
> - if (ratio < 0.001) {
> - ratio *= 1000;
> - unit = 'K';
> - }
> - snprintf(unit_buf, sizeof(unit_buf), "%c/sec", unit);
> + ratio = convert_unit_double(1000000000.0 * avg / total, &unit);
> +
> + if (unit != ' ')
> + snprintf(unit_buf, sizeof(unit_buf), "%c/sec", unit);
> print_metric(config, ctxp, NULL, "%8.3f", unit_buf, ratio);
> } else if (perf_stat_evsel__is(evsel, SMI_NUM)) {
> print_smi_cost(config, cpu, out, st, &rsd);
> diff --git a/tools/perf/util/units.c b/tools/perf/util/units.c
> index a46762aec4c9..32c39cfe209b 100644
> --- a/tools/perf/util/units.c
> +++ b/tools/perf/util/units.c
> @@ -33,28 +33,35 @@ unsigned long parse_tag_value(const char *str, struct parse_tag *tags)
> return (unsigned long) -1;
> }
>
> -unsigned long convert_unit(unsigned long value, char *unit)
> +double convert_unit_double(double value, char *unit)
> {
> *unit = ' ';
>
> - if (value > 1000) {
> - value /= 1000;
> + if (value > 1000.0) {
> + value /= 1000.0;
> *unit = 'K';
> }
>
> - if (value > 1000) {
> - value /= 1000;
> + if (value > 1000.0) {
> + value /= 1000.0;
> *unit = 'M';
> }
>
> - if (value > 1000) {
> - value /= 1000;
> + if (value > 1000.0) {
> + value /= 1000.0;
> *unit = 'G';
> }
>
> return value;
> }
>
> +unsigned long convert_unit(unsigned long value, char *unit)
> +{
> + double v = convert_unit_double((double)value, unit);
> +
> + return (unsigned long)v;
> +}
> +
> int unit_number__scnprintf(char *buf, size_t size, u64 n)
> {
> char unit[4] = "BKMG";
> diff --git a/tools/perf/util/units.h b/tools/perf/util/units.h
> index 99263b6a23f7..ea43e74e3240 100644
> --- a/tools/perf/util/units.h
> +++ b/tools/perf/util/units.h
> @@ -12,6 +12,7 @@ struct parse_tag {
>
> unsigned long parse_tag_value(const char *str, struct parse_tag *tags);
>
> +double convert_unit_double(double value, char *unit);
> unsigned long convert_unit(unsigned long value, char *unit);
> int unit_number__scnprintf(char *buf, size_t size, u64 n);
>
> --
> 2.25.1
>
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