APPLIED: [PATCH Xenial SRU] perf stat: Fix interval output values

[Luis Henriques]

On Fri, Oct 28, 2016 at 09:21:18AM -0600, Tim Gardner wrote:
> From: Jiri Olsa <jolsa at kernel.org>
> 
> BugLink: http://bugs.launchpad.net/bugs/1636647
>

This commit is already applied to xenial; it came in through an upstream
stable update.

Cheers,
--
Luís


> We broke interval data displays with commit:
> 
>   3f416f22d1e2 ("perf stat: Do not clean event's private stats")
> 
> This commit removed stats cleaning, which is important for '-r' option
> to carry counters data over the whole run. But it's necessary to clean
> it for interval mode, otherwise the displayed value is avg of all
> previous values.
> 
> Before:
>   $ perf stat -e cycles -a -I 1000 record
>   #           time             counts unit events
>        1.000240796         75,216,287      cycles
>        2.000512791        107,823,524      cycles
> 
>   $ perf stat report
>   #           time             counts unit events
>        1.000240796         75,216,287      cycles
>        2.000512791         91,519,906      cycles
> 
> Now:
>   $ perf stat report
>   #           time             counts unit events
>        1.000240796         75,216,287      cycles
>        2.000512791        107,823,524      cycles
> 
> Notice the second value being bigger (91,.. < 107,..).
> 
> This could be easily verified by using perf script which displays raw
> stat data:
> 
>   $ perf script
>   CPU  THREAD       VAL         ENA         RUN        TIME EVENT
>     0      -1  23855779  1000209530  1000209530  1000240796 cycles
>     1      -1  33340397  1000224964  1000224964  1000240796 cycles
>     2      -1  15835415  1000226695  1000226695  1000240796 cycles
>     3      -1   2184696  1000228245  1000228245  1000240796 cycles
>     0      -1  97014312  2000514533  2000514533  2000512791 cycles
>     1      -1  46121497  2000543795  2000543795  2000512791 cycles
>     2      -1  32269530  2000543566  2000543566  2000512791 cycles
>     3      -1   7634472  2000544108  2000544108  2000512791 cycles
> 
> The sum of the first 4 values is the first interval aggregated value:
> 
>   23855779 + 33340397 + 15835415 + 2184696 = 75,216,287
> 
> The sum of the second 4 values minus first value is the second interval
> aggregated value:
> 
>   97014312 + 46121497 + 32269530 + 7634472 - 75216287 = 107,823,524
> 
> Signed-off-by: Jiri Olsa <jolsa at kernel.org>
> Cc: Andi Kleen <ak at linux.intel.com>
> Cc: David Ahern <dsahern at gmail.com>
> Cc: Namhyung Kim <namhyung at kernel.org>
> Cc: Peter Zijlstra <a.p.zijlstra at chello.nl>
> Cc: Stephane Eranian <eranian at google.com>
> Link: http://lkml.kernel.org/r/1454485436-20639-1-git-send-email-jolsa@kernel.org
> Signed-off-by: Arnaldo Carvalho de Melo <acme at redhat.com>
> (cherry picked from commit 51fd2df1e882a3c2a3f4b6c9ff243a93c9046dba)
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
> ---
>  tools/perf/util/stat.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
> index 4a3a72c..6ce624c 100644
> --- a/tools/perf/util/stat.c
> +++ b/tools/perf/util/stat.c
> @@ -311,6 +311,16 @@ int perf_stat_process_counter(struct perf_stat_config *config,
>  
>  	aggr->val = aggr->ena = aggr->run = 0;
>  
> +	/*
> +	 * We calculate counter's data every interval,
> +	 * and the display code shows ps->res_stats
> +	 * avg value. We need to zero the stats for
> +	 * interval mode, otherwise overall avg running
> +	 * averages will be shown for each interval.
> +	 */
> +	if (config->interval)
> +		init_stats(ps->res_stats);
> +
>  	if (counter->per_pkg)
>  		zero_per_pkg(counter);
>  
> -- 
> 2.7.4
> 
> 
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team