linux-kernel - Re: [PATCH v4 2/2] perf report: Implement visual marker for macro fusion in annotate

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Date:   Fri, 7 Jul 2017 11:51:11 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     Jiri Olsa <jolsa@...nel.org>, peterz@...radead.org,
        Ingo Molnar <mingo@...nel.org>,
        alexander.shishkin@...ux.intel.com, Linux-kernel@...r.kernel.org,
        ak@...ux.intel.com, kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v4 2/2] perf report: Implement visual marker for macro
 fusion in annotate

Em Fri, Jul 07, 2017 at 01:06:35PM +0800, Jin Yao escreveu:
> For marking the fused instructions clearly, This patch adds a line
> before the first instruction of pair and joins it with the arrow of the
> jump.
> 
> For example, when je is selected in annotate view, the line before cmpl
> is displayed and joins the arrow of je.
> 
>        │   ┌──cmpl   $0x0,argp_program_version_hook
>  81.93 │   ├──je     20
>        │   │  lock   cmpxchg %esi,0x38a9a4(%rip)
>        │   │↓ jne    29
>        │   │↓ jmp    43
>  11.47 │20:└─→cmpxch %esi,0x38a999(%rip)
> 
> That means the cmpl+je is fused instruction pair and they should be
> considered together.

I applied this one, no unnecessary parsing of cpuid done at each
jump->target arrow rendering, much better, thanks!

One thing for a follow up patch:

We have this when the cursor is at a jump instruction:

       │      ┌──test   %ecx,%ecx
->     │      ├──je     714cf
       │      │  mov    LINES+0xb40,%edx
       │      │  test   %edx,%edx
       │      │↓ je     71580
       │714cf:└─→mov    LINES+0x10c8,%eax

But if we go up a line, to that "test" instruction, we get:

->     │         test   %ecx,%ecx
       │       ↓ je     714cf
       │         mov    LINES+0xb40,%edx
       │         test   %edx,%edx
       │       ↓ je     71580
       │714cf:   mov    LINES+0x10c8,%eax

I suggest that this be changed to:

->     │       ┌─test   %ecx,%ecx
       │       ↓ je     714cf
       │         mov    LINES+0xb40,%edx
       │         test   %edx,%edx
       │       ↓ je     71580
       │714cf:   mov    LINES+0x10c8,%eax

I.e. even before going to the jump instruction line with the cursor, we
would see the fused instructions.

To do that perhaps we should improve annotate_browser__draw_current_jump
to improve that part that looks for is_valid_jump() to consider
instructions that could be fused with jumps for the machine where the
perf data came from, etc.

But the current situation is better already, thanks for your work,
applied!

- Arnaldo