linux-kernel - Re: [PATCH v2 6/7] perf diff: Print the basic block cycles diff

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Date:   Wed, 5 Jun 2019 13:44:08 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, 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 v2 6/7] perf diff: Print the basic block cycles diff

On Mon, Jun 03, 2019 at 10:36:16PM +0800, Jin Yao wrote:
> perf record -b ./div
> perf record -b ./div
> 
> Following is the default perf diff output
> 
>  # perf diff
> 
>  # Event 'cycles'
>  #
>  # Baseline  Delta Abs  Shared Object     Symbol
>  # ........  .........  ................  ....................................
>  #
>      49.03%     +0.30%  div               [.] main
>      16.29%     -0.20%  libc-2.23.so      [.] __random
>      18.82%     -0.07%  libc-2.23.so      [.] __random_r
>       8.11%     -0.04%  div               [.] compute_flag
>       2.25%     +0.01%  div               [.] rand@plt
>       0.00%     +0.01%  [kernel.vmlinux]  [k] task_tick_fair
>       5.46%     +0.01%  libc-2.23.so      [.] rand
>       0.01%     -0.01%  [kernel.vmlinux]  [k] native_irq_return_iret
>       0.00%     -0.00%  [kernel.vmlinux]  [k] interrupt_entry
> 
> This patch creates a new computation selection 'cycles'.
> 
>  # perf diff -c cycles
> 
>  # Event 'cycles'
>  #
>  # Baseline         Block cycles diff [start:end]  Shared Object     Symbol
>  # ........  ....................................  ................  ....................................
>  #
>      49.03%        -9 [         4ef:         520]  div               [.] main
>      49.03%         0 [         4e8:         4ea]  div               [.] main
>      49.03%         0 [         4ef:         500]  div               [.] main
>      49.03%         0 [         4ef:         51c]  div               [.] main
>      49.03%         0 [         4ef:         535]  div               [.] main
>      18.82%         0 [       3ac40:       3ac4d]  libc-2.23.so      [.] __random_r
>      18.82%         0 [       3ac40:       3ac5c]  libc-2.23.so      [.] __random_r
>      18.82%         0 [       3ac40:       3ac76]  libc-2.23.so      [.] __random_r
>      18.82%         0 [       3ac40:       3ac88]  libc-2.23.so      [.] __random_r
>      18.82%         0 [       3ac90:       3ac9c]  libc-2.23.so      [.] __random_r
>      16.29%        -8 [       3aac0:       3aac0]  libc-2.23.so      [.] __random
>      16.29%         0 [       3aac0:       3aad2]  libc-2.23.so      [.] __random
>      16.29%         0 [       3aae0:       3aae7]  libc-2.23.so      [.] __random
>      16.29%         0 [       3ab03:       3ab0f]  libc-2.23.so      [.] __random
>      16.29%         0 [       3ab14:       3ab1b]  libc-2.23.so      [.] __random
>      16.29%         0 [       3ab28:       3ab2e]  libc-2.23.so      [.] __random
>      16.29%         0 [       3ab4a:       3ab53]  libc-2.23.so      [.] __random
>       8.11%         0 [         640:         644]  div               [.] compute_flag
>       8.11%         0 [         649:         659]  div               [.] compute_flag
>       5.46%         0 [       3af60:       3af60]  libc-2.23.so      [.] rand
>       5.46%         0 [       3af60:       3af64]  libc-2.23.so      [.] rand
>       2.25%         0 [         490:         490]  div               [.] rand@plt
>       0.01%        26 [      c00a27:      c00a27]  [kernel.vmlinux]  [k] native_irq_return_iret
>       0.00%      -157 [      2bf9f2:      2bfa63]  [kernel.vmlinux]  [k] update_blocked_averages
>       0.00%       -56 [      2bf980:      2bf9d3]  [kernel.vmlinux]  [k] update_blocked_averages
>       0.00%        48 [      2bf934:      2bf942]  [kernel.vmlinux]  [k] update_blocked_averages
>       0.00%         3 [      2bfb38:      2bfb67]  [kernel.vmlinux]  [k] update_blocked_averages
>       0.00%         0 [      2bf968:      2bf97b]  [kernel.vmlinux]  [k] update_blocked_averages
> 

so what I'd expect would be Baseline column with cycles and another
column showing the differrence (in cycles) for given symbol

> "[start:end]" indicates the basic block range. The output is sorted
> by "Baseline" and the basic blocks in the same function are sorted
> by cycles diff.

hum, why is there multiple basic blocks [start:end] for a symbol?

thanks,
jirka