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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 10 Jan 2024 14:41:16 -0800
Message-ID: <CAHk-=wiXpsxMcQb7MhL-AxOityTajK0G8eWeBOzX-qBJ9X2DSw@mail.gmail.com>
Subject: Re: [GIT PULL] Scheduler changes for v6.8
To: Ingo Molnar <mingo@kernel.org>, Vincent Guittot <vincent.guittot@linaro.org>
Cc: linux-kernel@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>, 
	Thomas Gleixner <tglx@linutronix.de>, Juri Lelli <juri.lelli@redhat.com>, 
	Dietmar Eggemann <dietmar.eggemann@arm.com>, Steven Rostedt <rostedt@goodmis.org>, 
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>, 
	Daniel Bristot de Oliveira <bristot@redhat.com>, Valentin Schneider <vschneid@redhat.com>
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On Wed, 10 Jan 2024 at 14:19, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> Just a note that I'm currently bisecting into this merge for a
> horrendous performance regression.
>
> It makes my empty kernel build go from 22 seconds to 44 seconds, and
> makes a full kernel build enormously slower too.
>
> I haven't finished the bisection, but it's now inside *just* this
> pull, so I can already tell that I'm going to revert something in
> here, because this has been making my merge window miserable.

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.

             Linus