linux-kernel - Re: [PATCH v3 2/2] Support interactive annotation of code without symbols

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Date:   Mon, 24 Feb 2020 23:46:51 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Ravi Bangoria <ravi.bangoria@...ux.ibm.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 v3 2/2] Support interactive annotation of code without
 symbols



On 2/24/2020 9:56 PM, Ravi Bangoria wrote:
> 
> 
> On 2/24/20 7:52 AM, Jin Yao wrote:
>> For perf report on stripped binaries it is currently impossible to do
>> annotation. The annotation state is all tied to symbols, but there are
>> either no symbols, or symbols are not covering all the code.
>>
>> We should support the annotation functionality even without symbols.
>>
>> This patch fakes a symbol and the symbol name is the string of address.
>> After that, we just follow current annotation working flow.
>>
>> For example,
>>
>> 1. perf report
>>
>> Overhead  Command  Shared Object     Symbol
>>    20.67%  div      libc-2.27.so      [.] __random_r
>>    17.29%  div      libc-2.27.so      [.] __random
>>    10.59%  div      div               [.] 0x0000000000000628
>>     9.25%  div      div               [.] 0x0000000000000612
>>     6.11%  div      div               [.] 0x0000000000000645
>>
>> 2. Select the line of "10.59%  div      div               [.] 
>> 0x0000000000000628" and ENTER.
>>
>> Annotate 0x0000000000000628
>> Zoom into div thread
>> Zoom into div DSO (use the 'k' hotkey to zoom directly into the kernel)
>> Browse map details
>> Run scripts for samples of symbol [0x0000000000000628]
>> Run scripts for all samples
>> Switch to another data file in PWD
>> Exit
>>
>> 3. Select the "Annotate 0x0000000000000628" and ENTER.
>>
>> Percent│
>>         │
>>         │
>>         │     Disassembly of section .text:
>>         │
>>         │     0000000000000628 <.text+0x68>:
>>         │       divsd %xmm4,%xmm0
>>         │       divsd %xmm3,%xmm1
>>         │       movsd (%rsp),%xmm2
>>         │       addsd %xmm1,%xmm0
>>         │       addsd %xmm2,%xmm0
>>         │       movsd %xmm0,(%rsp)
> This might be an add on...
> 
> Even though there are samples on a particular instruction, 'Percent' column
> is empty, I guess, because we don't have symbol length?
> 
> Should we show 'global percent'? Or nr samples? Will it be useful?
> 
> Ravi
> 

As the mail I reply to Jiri, if we use the Jiri's idea, we can collect 
the hits for dummy symbols then we can show the percent of dummy symbol 
here.

Thanks
Jin Yao