linux-kernel - Re: [PATCH v3 0/3] perf report/annotate: Support average IPC and IPC coverage for function

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Date:   Wed, 28 Nov 2018 20:39:23 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Ingo Molnar <mingo@...nel.org>
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 v3 0/3] perf report/annotate: Support average IPC and IPC
 coverage for function



On 11/28/2018 5:10 PM, Ingo Molnar wrote:
> 
> * Jin Yao <yao.jin@...ux.intel.com> wrote:
> 
>> Add supporting of displaying the average IPC and IPC coverage
>> percentage per function.
>>
>> For example,
>>
>> $ perf record -b ...
>> $ perf report -s symbol or
>>    perf report -s symbol --stdio
>>
>> Overhead  Symbol                           IPC   [IPC Coverage]
>>    39.60%  [.] __random                     2.30  [ 54.8%]
>>    18.02%  [.] main                         0.43  [ 54.3%]
>>    14.21%  [.] compute_flag                 2.29  [100.0%]
>>    14.16%  [.] rand                         0.36  [100.0%]
>>     7.06%  [.] __random_r                   2.57  [ 70.5%]
>>     6.85%  [.] rand@plt                     0.00  [  0.0%]
>>    ...
>>
>> $ perf annotate --stdio2
>>
>> Percent  IPC Cycle (Average IPC: 2.30, IPC Coverage: 54.8%)
>>
>>                          Disassembly of section .text:
>>
>>                          000000000003aac0 <random@@GLIBC_2.2.5>:
>>    8.32  3.28              sub    $0x18,%rsp
>>          3.28              mov    $0x1,%esi
>>          3.28              xor    %eax,%eax
>>          3.28              cmpl   $0x0,argp_program_version_hook@@GLIBC_2.2.5+0x1e0
>>   11.57  3.28     1      ↓ je     20
>>                            lock   cmpxchg %esi,__abort_msg@@GLIBC_PRIVATE+0x8a0
>>                          ↓ jne    29
>>                          ↓ jmp    43
>>   11.57  1.10        20:   cmpxchg %esi,__abort_msg@@GLIBC_PRIVATE+0x8a0
> 
> That's a nice feature: please add meaningful documentation, accessible
> via the perf help system preferably, that outlines how the IPC metrics
> should be interpreted and how they are useful when optimizing programs.
> 
> Thanks,
> 
> 	Ingo
> 

Hi Ingo,

Thanks so much for your comments! I think I will add some explanations 
in perf/Documentation/perf-report.txt, maybe somewhere around the 
sort_key section (-s::).

Thanks
Jin Yao