[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CAHk-=wgXoyxy99HnEFcvf+eUZAS5=ekWt_y84LC3P+0osxh6Jw@mail.gmail.com>
Date: Wed, 21 Jun 2023 12:31:45 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Tejun Heo <tj@...nel.org>
Cc: Pin-yen Lin <treapking@...omium.org>,
Brian Norris <briannorris@...omium.org>,
jiangshanlai@...il.com, peterz@...radead.org,
linux-kernel@...r.kernel.org, kernel-team@...a.com,
joshdon@...gle.com, brho@...gle.com, nhuck@...gle.com,
agk@...hat.com, snitzer@...nel.org, void@...ifault.com
Subject: Re: [PATCHSET v1 wq/for-6.5] workqueue: Improve unbound workqueue
execution locality
On Wed, 21 Jun 2023 at 12:16, Tejun Heo <tj@...nel.org> wrote:
>
> I find that perplexing given that switching to a per-cpu workqueue remedies
> the situation quite a bit, which is how this patchset came to be. #3 is the
> same as per-cpu workqueue, so if you're seeing noticeably different
> performance numbers between #3 and per-cpu workqueue, there's something
> wrong with either the code or test setup.
Or maybe there's some silly thinko in the wq code that is hidden by
the percpu code.
For example, WQ_UNBOUND triggers a lot of other overhead at least on
wq allocation and free. Maybe some of that stuff then indirectly
affects workqueue execution even when strict cpu affinity is set.
Pin-Yen Li - can you do a system-wide profile of the two cases (the
percpu case vs the "strict cpu affinity" one), to see if something
stands out?
Linus
Powered by blists - more mailing lists