Re: EXT4 IOPS degradation in 5.10 compared to 5.4

Linux kernel regression tracking (#adding)
2023-01-12T15:06:26Z

[CCing the regression list, as it should be in the loop for regressions:
https://docs.kernel.org/admin-guide/reporting-regressions.html]

[TLDR: I'm adding this report to the list of tracked Linux kernel
regressions; the text you find below is based on a few templates
paragraphs you might have encountered already in similar form.
See link in footer if these mails annoy you.]

On 12.01.23 03:06, Bhatnagar, Rishabh wrote:
> Hi Theodore/Jan
>
> Please ignore the previous mail which isn't formatted well.
>
>
> We have been seeing a consistent 3% degradation in IOPS score between
> 5.4 and 5.10 stable kernels while running fio tests.
>
> I'm running test case on m6g.8xlarge AWS instances using arm64. The test
> involves:
>
> [...]>
> After doing some kernel bisecting between we were able to pinpoint this
> commit that drops the iops score by 10~15 points (~3%).
> ext4: avoid unnecessary transaction starts during writeback
> (6b8ed62008a49751fc71fefd2a4f89202a7c2d4d)
> [...]

Thanks for the report. To be sure the issue doesn't fall through the
cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
tracking bot:

#regzbot ^introduced 6b8ed62008a49751fc71
#regzbot title ext4: consistent 3% degradation in IOPS score
#regzbot ignore-activity

This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
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