linux-kernel - Re: [PATCH 0/7] Improve performance of 'faddr2line'

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Date: Tue, 12 Mar 2024 16:06:16 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Brian Johannesmeyer <bjohannesmeyer@...il.com>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/7] Improve performance of 'faddr2line'

On Mon, Mar 11, 2024 at 09:40:12PM +0100, Brian Johannesmeyer wrote:
> Hello,
> 
> I was looking at the performance of faddr2line and noticed that it spends
> most of its time performing two tasks:
> - (1) Making redundant calls to readelf and addr2line for each address
>   (e.g., it makes 7 readelf calls and 2 addr2line calls when converting 1
> address, and it makes 252 readelf calls and 51 addr2line calls when
> converting 50 addresses); and
> - (2) Calculating a symbol’s size by unnecessarily looping through every
>   symbol in a particular section.
> 
> This patch series consists of the following parts:
> - Patches 1-2 reduce the total number of readelf calls to one,
> - Patches 3-4 make minor changes in preparation for the following patches,
> - Patches 5-6 reduce the total number of addr2line calls to one, and
> - Patch 7 modifies the symbol size calculation to only check two symbols.
> 
> I evaluated the performance of the patch series by running faddr2line with
> a standard kernel image (X86_64 defconfig with CONFIG_DEBUG_INFO enabled).
> When converting only 1 address, the patch series gives a negligible
> speedup. When converting 50 addresses, however, it gives a 15x speedup.

This looks really nice.

If testing runs ok, I'll go ahead and queue it up.

Thanks!

-- 
Josh