[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 20.06.23 10:14, Swapnil Sapkal wrote: > > On 4/22/2023 1:13 PM, tip-bot2 for Mathieu Desnoyers wrote: >> The following commit has been merged into the sched/core branch of tip: >> >> Commit-ID: 223baf9d17f25e2608dbdff7232c095c1e612268 >> Gitweb: >> https://git.kernel.org/tip/223baf9d17f25e2608dbdff7232c095c1e612268 >> Author: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> >> AuthorDate: Thu, 20 Apr 2023 10:55:48 -04:00 >> Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> >> CommitterDate: Fri, 21 Apr 2023 13:24:20 +02:00 >> >> sched: Fix performance regression introduced by mm_cid >> >> Introduce per-mm/cpu current concurrency id (mm_cid) to fix a PostgreSQL >> sysbench regression reported by Aaron Lu. > [...] > I run standard benchmarks as a part of kernel performance regression > testing. When I run these benchmarks against v6.3.0 to v6.4-rc1, > I have seen performance regression in hackbench running with threads. > When I did > git bisect it pointed to this commit and reverting this commit helps > regains > the performance. This regression is not seen with hackbench processes. > Following are the results from 1 Socket 4th generation EPYC > Processor(1 X 96C/192T) configured in NPS1 mode. This regression > becomes more severe as the number of core count increases. > > The numbers on a 1 Socket Bergamo (1 X 128 cores/256 threads) is > significantly worse. > [...] 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 223baf9d17f #regzbot title sched: performance regression in hackbench (partly solved in -next by c1753fd02a00, partially caused by df323337e50) #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 That page also explains what to do if mails like this annoy you.
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