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Date:	Mon, 5 Jan 2015 16:04:42 +0000
From:	"Liang, Kan" <kan.liang@...el.com>
To:	"acme@...nel.org" <acme@...nel.org>,
	"jolsa@...hat.com" <jolsa@...hat.com>,
	"namhyung@...nel.org" <namhyung@...nel.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>
Subject: RE: [PATCH V6 1/1] perf tool: perf diff support for different
 binaries

Hi Arnaldo,

The patch is one month old. Kim and Jirka have reviewed it. 

There is also another perf diff related patch which has similar situation.
https://lkml.org/lkml/2014/12/1/380
It was also reviewed by Jirka a month ago.

Both of them still apply to current perf/core. 
Should I re-post them for more review?

Thanks,
Kan

> 
> From: Kan Liang <kan.liang@...el.com>
> 
> Currently, the perf diff only works with same binaries. That's because it
> compares the symbol start address. It doesn't work if the perf.data comes
> from different binaries. This patch matches the function names.
> 
> Here is an examples.
> The only difference between example_v1.c and example_v2.c is the
> location of f2 and f3. There is no change in behavior, but the previous perf
> diff display the wrong differential profile.
> 
> example_v1.c
> 
> noinline void f3(void)
> {
>         volatile int i;
>         for (i = 0; i < 10000;) {
> 
>                 if(i%2)
>                         i++;
>                 else
>                         i++;
>         }
> }
> 
> noinline void f2(void)
> {
>         volatile int a = 100, b, c;
>         for (b = 0; b < 10000; b++)
>                 c = a * b;
> 
> }
> 
> noinline void f1(void)
> {
>                 f2();
>                 f3();
> }
> 
> int main()
> {
>         int i;
>         for (i = 0; i < 100000; i++)
>                 f1();
> }
> 
> example_v2.c
> 
> noinline void f2(void)
> {
>         volatile int a = 100, b, c;
>         for (b = 0; b < 10000; b++)
>                 c = a * b;
> }
> 
> noinline void f3(void)
> {
>         volatile int i;
>         for (i = 0; i < 10000;) {
>                 if(i%2)
>                         i++;
>                 else
>                         i++;
>         }
> }
> 
> noinline void f1(void)
> {
>                 f2();
>                 f3();
> }
> 
> int main()
> {
>         int i;
>         for (i = 0; i < 100000; i++)
>                 f1();
> }
> 
> [lk@...alhost perf_diff]$ gcc example_v1.c -o example [lk@...alhost
> perf_diff]$ perf record -o example_v1.data ./example [ perf record:
> Woken up 4 times to write data ] [ perf record: Captured and wrote 0.813
> MB example_v1.data (~35522
> samples) ]
> 
> [lk@...alhost perf_diff]$ gcc example_v2.c -o example [lk@...alhost
> perf_diff]$ perf record -o example_v2.data ./example [ perf record:
> Woken up 4 times to write data ] [ perf record: Captured and wrote 0.824
> MB example_v2.data (~36015
> samples) ]
> 
> Old perf diff result.
> [lk@...alhost perf_diff]$ perf diff example_v1.data example_v2.data
> Event 'cycles'
> 
>  Baseline    Delta  Shared Object     Symbol
>  ........  .......  ................  ...............................
> 
>                      [kernel.vmlinux]  [k] __perf_event_task_sched_out
>      0.00%           [kernel.vmlinux]  [k] apic_timer_interrupt
>                      [kernel.vmlinux]  [k] idle_cpu
>                      [kernel.vmlinux]  [k] intel_pstate_timer_func
>                      [kernel.vmlinux]  [k] native_read_msr_safe
>      0.00%           [kernel.vmlinux]  [k] native_read_tsc
>      0.00%           [kernel.vmlinux]  [k] native_write_msr_safe
>                      [kernel.vmlinux]  [k] ntp_tick_length
>      0.00%           [kernel.vmlinux]  [k] rb_erase
>      0.00%           [kernel.vmlinux]  [k] tick_sched_timer
>      0.00%           [kernel.vmlinux]  [k] unmap_single_vma
>      0.00%           [kernel.vmlinux]  [k] update_wall_time
>      0.00%           example           [.] f1
>     46.24%           example           [.] f2
>     53.71%   -7.55%  example           [.] f3
>             +53.81%  example           [.] f3
>      0.02%           example           [.] main
> 
> New perf diff result.
> [lk@...alhost perf_diff]$ perf diff example_v1.data example_v2.data
>                      [kernel.vmlinux]  [k] __perf_event_task_sched_out
>      0.00%           [kernel.vmlinux]  [k] apic_timer_interrupt
>                      [kernel.vmlinux]  [k] idle_cpu
>                      [kernel.vmlinux]  [k] intel_pstate_timer_func
>                      [kernel.vmlinux]  [k] native_read_msr_safe
>      0.00%           [kernel.vmlinux]  [k] native_read_tsc
>      0.00%           [kernel.vmlinux]  [k] native_write_msr_safe
>                      [kernel.vmlinux]  [k] ntp_tick_length
>      0.00%           [kernel.vmlinux]  [k] rb_erase
>      0.00%           [kernel.vmlinux]  [k] tick_sched_timer
>      0.00%           [kernel.vmlinux]  [k] unmap_single_vma
>      0.00%           [kernel.vmlinux]  [k] update_wall_time
>      0.00%           example           [.] f1
>     46.24%   -0.08%  example           [.] f2
>     53.71%   +0.11%  example           [.] f3
>      0.02%           example           [.] main
> 
> Signed-off-by: Kan Liang <kan.liang@...el.com>
> Acked-by: Namhyung Kim <namhyung@...nel.org>
> Acked-by: Jiri Olsa <jolsa@...nel.org>
> 
> ---
> 
> The patch is seperated from "[PATCH V4 0/3] perf tool: perf diff sort
> changes" patch set.
> The first patch of the patch set has been merged.
> The third patch of the patch set for symoff will be sent out by another
> thread.
> 
> Changes since V4:
>  - Seperate from old patch set
>  - Add an example in changelog
>  - Update man page
> 
> Changes since V5:
>  - Correct patch style
> 
>  tools/perf/Documentation/perf-diff.txt | 5 +++++
>  tools/perf/util/sort.c                 | 9 +++++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/tools/perf/Documentation/perf-diff.txt
> b/tools/perf/Documentation/perf-diff.txt
> index e463caa..5182661 100644
> --- a/tools/perf/Documentation/perf-diff.txt
> +++ b/tools/perf/Documentation/perf-diff.txt
> @@ -20,6 +20,11 @@ If no parameters are passed it will assume
> perf.data.old and perf.data.
>  The differential profile is displayed only for events matching both
> specified perf.data files.
> 
> +If no parameters are passed the samples will be sorted by dso and symbol.
> +As the perf.data files could come from different binaries, the symbols
> +addresses could vary. So perf diff is based on the comparison of the
> +files and symbols name.
> +
>  OPTIONS
>  -------
>  -D::
> diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c index
> 9139dda..e0e4173 100644
> --- a/tools/perf/util/sort.c
> +++ b/tools/perf/util/sort.c
> @@ -1432,6 +1432,15 @@ int sort_dimension__add(const char *tok)
>  			sort__has_parent = 1;
>  		} else if (sd->entry == &sort_sym) {
>  			sort__has_sym = 1;
> +			/*
> +			 * perf diff displays the performance difference
> amongst
> +			 * two or more perf.data files. Those files could
> come
> +			 * from different binaries. So we should not
> compare
> +			 * their ips, but the name of symbol.
> +			 */
> +			if (sort__mode == SORT_MODE__DIFF)
> +				sd->entry->se_collapse = sort__sym_sort;
> +
>  		} else if (sd->entry == &sort_dso) {
>  			sort__has_dso = 1;
>  		}
> --
> 1.8.3.2

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