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Date: Tue, 15 Apr 2014 15:35:35 +0900
From: Namhyung Kim <namhyung@...il.com>
To: Andi Kleen <andi@...stfloor.org>
Cc: jolsa@...hat.com, acme@...radead.org, linux-kernel@...r.kernel.org,
Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH] perf, tools: Support spark lines in perf stat v2
Hi Andi,
On Mon, 14 Apr 2014 09:09:31 -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
>
> perf stat -rX prints the stddev for multiple measurements.
> Just looking at the stddev for judging the quality of the data
> is a bit dangerous The simplest sanity check is to just look
> at a simple plot. This patchs add a sparkline to the end
> of the measurements to make it simple to judge the data.
>
> The sparkline only uses UTF-8, so should be readable
> in all modern tools and terminals.
>
> The sparkline is between the minimum and maximum of the data,
> so it's mainly a indicator of variance. To keep the code
> simple and make the output not too wide only the first
> 8 values are printed. If more values are there it adds '..'
>
> The code is inspired by Zach Holman's spark shell script.
>
> Example output (view in non-proportial font):
>
> Performance counter stats for 'true' (10 runs):
>
> 0.175672 task-clock (msec) # 0.555 CPUs utilized ( +- 1.77% ) █▄▁▁▁▁▁▁..
> 0 context-switches # 0.000 K/sec
> 0 cpu-migrations # 0.000 K/sec
> 114 page-faults # 0.647 M/sec ( +- 0.14% ) ▁█▁▁████..
> 520,798 cycles # 2.965 GHz ( +- 1.75% ) █▄▁▁▁▁▁▁..
> 433,525 instructions # 0.83 insns per cycle ( +- 0.28% ) ▅▇▅▄▇█▁▆..
> 83,012 branches # 472.537 M/sec ( +- 0.31% ) ▅▇▆▄▇█▁▆..
> 3,157 branch-misses # 3.80% of all branches ( +- 2.55% ) ▇█▃▅▁▃▁▂..
>
> 0.000316660 seconds time elapsed ( +- 1.78% ) █▅▁▁▁▁▁▁..
>
> As you can see even in the most simple run there are quite interesting
> patterns. The time sparkline suggests it would be also useful to have an option
> to throw the first measurement away.
>
> Known issues:
> - Makes the perf stat output wider. Could be adjust by shrinking
> some white space. Not done so far.
> - No output for -A/--per-socket/--per-core with -rX. This code
> is missing the basic noise detection code. Once it's added there
> sparklines could be shown too.
>
> v2: Avoid printing spark lines for normal CSV case (Jiri)
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
[SNIP]
> diff --git a/tools/perf/util/spark.c b/tools/perf/util/spark.c
> new file mode 100644
> index 0000000..a677d2c
> --- /dev/null
> +++ b/tools/perf/util/spark.c
> @@ -0,0 +1,45 @@
> +#include <stdio.h>
> +#include <limits.h>
> +#include "spark.h"
> +
> +#define NUM_SPARKS 8
> +#define SPARK_SHIFT 8
> +
> +/* Print spark lines on outf for numval values in val. */
> +void print_spark(FILE *outf, unsigned long *val, int numval)
> +{
> + static const char *ticks[NUM_SPARKS] = {
> + "▁", "▂", "▃", "▄", "▅", "▆", "▇", "█"
> + };
> + int i;
> + unsigned long min = LONG_MAX, max = 0, f;
s/LONG_MAX/ULONG_MAX/ ?
> +
> + for (i = 0; i < numval; i++) {
> + if (val[i] < min)
> + min = val[i];
> + if (val[i] > max)
> + max = val[i];
> + }
> + f = ((max - min) << SPARK_SHIFT) / (NUM_SPARKS - 1);
> + if (f < 1)
> + f = 1;
> + for (i = 0; i < numval; i++) {
> + fputs(ticks[((val[i] - min) << SPARK_SHIFT) / f], outf);
> + }
> +}
> +
> +#ifdef TEST
> +#include <stdlib.h>
> +
> +int main(int ac, char **av)
> +{
> + unsigned long *val = calloc(ac - 1, sizeof(unsigned long));
> + int i;
> +
> + for (i = 1; i < ac; i++)
> + val[i - 1] = strtoul(av[i], NULL, 0);
> + print_spark(stdout, val, ac - 1);
> + putchar('\n');
> + return 0;
> +}
> +#endif
Hmm.. test codes usually live in the tools/perf/tests directory.
> diff --git a/tools/perf/util/spark.h b/tools/perf/util/spark.h
> new file mode 100644
> index 0000000..f2d5ac5
> --- /dev/null
> +++ b/tools/perf/util/spark.h
> @@ -0,0 +1,3 @@
> +#pragma once
> +void print_spark(FILE *outf, unsigned long *val, int numval);
> +
> diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
> index 6506b3d..2b26d74 100644
> --- a/tools/perf/util/stat.c
> +++ b/tools/perf/util/stat.c
> @@ -1,10 +1,16 @@
> #include <math.h>
> +#include <stdio.h>
>
> #include "stat.h"
> +#include "spark.h"
>
> void update_stats(struct stats *stats, u64 val)
> {
> double delta;
> + int n = stats->n;
> +
> + if (n < NUM_SPARK_VALS)
> + stats->svals[n] = val;
>
> stats->n++;
> delta = val - stats->mean;
> @@ -61,3 +67,30 @@ double rel_stddev_stats(double stddev, double avg)
>
> return pct;
> }
> +
> +static int all_the_same(unsigned long *vals, int len)
> +{
> + int i;
> + unsigned long v0 = vals[0];
> +
> + for (i = 1; i < len; i++)
> + if (vals[i] != v0)
> + return 0;
> + return 1;
> +}
> +
> +void print_stat_spark(FILE *f, struct stats *stat)
> +{
> + int n = stat->n, len;
> +
> + if (n <= 1)
> + return;
> + len = n;
It seems the 'n' is not needed at all - just use 'len'.
> + if (len > NUM_SPARK_VALS)
> + len = NUM_SPARK_VALS;
> + if (all_the_same(stat->svals, len))
> + return;
Why does it skip printing if all values are same? I think you wanted to
skip the "all zero" (uncounted) case, right?
Also adding a few blank lines might improve readability a bit IMHO.
Thanks,
Namhyung
> + print_spark(f, stat->svals, len);
> + if (stat->n > NUM_SPARK_VALS)
> + fputs("..", f);
> +}
> diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
> index ae8ccd7..1b4dc71 100644
> --- a/tools/perf/util/stat.h
> +++ b/tools/perf/util/stat.h
> @@ -1,12 +1,16 @@
> #ifndef __PERF_STATS_H
> #define __PERF_STATS_H
>
> +#include <stdio.h>
> #include "types.h"
>
> +#define NUM_SPARK_VALS 8 /* support spark line on first N items */
> +
> struct stats
> {
> double n, mean, M2;
> u64 max, min;
> + unsigned long svals[NUM_SPARK_VALS];
> };
>
> void update_stats(struct stats *stats, u64 val);
> @@ -14,12 +18,18 @@ double avg_stats(struct stats *stats);
> double stddev_stats(struct stats *stats);
> double rel_stddev_stats(double stddev, double avg);
>
> +void print_stat_spark(FILE *f, struct stats *stat);
> +
> static inline void init_stats(struct stats *stats)
> {
> + int i;
> +
> stats->n = 0.0;
> stats->mean = 0.0;
> stats->M2 = 0.0;
> stats->min = (u64) -1;
> stats->max = 0;
> + for (i = 0; i < NUM_SPARK_VALS; i++)
> + stats->svals[i] = 0;
> }
> #endif
--
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