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

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Message-Id: <ec14c25e-e868-a073-2799-55d55ae23e1f@linux.ibm.com>
Date:   Mon, 24 Feb 2020 19:26:57 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.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,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH v3 2/2] Support interactive annotation of code without
 symbols



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