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Message-ID: <ZZ/MY0KEGXotqGHY@gmail.com>
Date: Thu, 11 Jan 2024 12:09:23 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Vincent Guittot <vincent.guittot@...aro.org>,
linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Juri Lelli <juri.lelli@...hat.com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Valentin Schneider <vschneid@...hat.com>
Subject: [GIT PULL] scheduler fixes
* Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> On Wed, 10 Jan 2024 at 14:41, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> >
> > It's one of these two:
> >
> > f12560779f9d sched/cpufreq: Rework iowait boost
> > 9c0b4bb7f630 sched/cpufreq: Rework schedutil governor performance estimation
> >
> > one more boot to go, then I'll try to revert whichever causes my
> > machine to perform horribly much worse.
>
> I guess it should come as no surprise that the result is
>
> 9c0b4bb7f6303c9c4e2e34984c46f5a86478f84d is the first bad commit
>
> but to revert cleanly I will have to revert all of
>
> b3edde44e5d4 ("cpufreq/schedutil: Use a fixed reference frequency")
> f12560779f9d ("sched/cpufreq: Rework iowait boost")
> 9c0b4bb7f630 ("sched/cpufreq: Rework schedutil governor
> performance estimation")
>
> This is on a 32-core (64-thread) AMD Ryzen Threadripper 3970X, fwiw.
>
> I'll keep that revert in my private test-tree for now (so that I have
> a working machine again), but I'll move it to my main branch soon
> unless somebody has a quick fix for this problem.
Thanks a lot for bisecting this, and ack on the revert in any case, these
are relatively fresh changes that clearly didn't get enough testing - sorry!
I also made the revert in sched/urgent & added a changelog, which you can
pull from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-2024-01-11
# HEAD: 250ce3c1169743f3575cc5937fccd72380052795 Revert "sched/cpufreq: Rework schedutil governor performance estimation" and dependent commits
Revert recent changes to the sched_util logic, to address a bad
performance regression that increased kernel build time on Linus's
64-CPU desktop system substantially.
Lightly build and boot tested.
Thanks,
Ingo
------------------>
Ingo Molnar (1):
Revert "sched/cpufreq: Rework schedutil governor performance estimation" and dependent commits
include/linux/energy_model.h | 1 +
kernel/sched/core.c | 90 +++++++++++++++++++++++-----------------
kernel/sched/cpufreq_schedutil.c | 90 ++++++++++++----------------------------
kernel/sched/fair.c | 22 ++--------
kernel/sched/sched.h | 84 +++++++++++++++++++++++++++++++++----
5 files changed, 160 insertions(+), 127 deletions(-)
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