linux-kernel - Re: [PATCHSET v6 0/4] Split iowait into two states

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJZ5v0iZqKGG+wCZYrA1t7mXvrW6Fo-Zb3d17Bofg3NSb2kPEg@mail.gmail.com>
Date: Wed, 4 Sep 2024 16:42:19 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>, Jens Axboe <axboe@...nel.dk>
Cc: linux-kernel@...r.kernel.org, tglx@...utronix.de, 
	daniel.lezcano@...aro.org, linux-pm@...r.kernel.org
Subject: Re: [PATCHSET v6 0/4] Split iowait into two states

On Wed, Sep 4, 2024 at 4:28 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Mon, Aug 19, 2024 at 09:39:45AM -0600, Jens Axboe wrote:
> > Hi,
> >
> > This is v6 of the patchset where the current in_iowait state is split
> > into two parts:
> >
> > 1) The "task is sleeping waiting on IO", and would like cpufreq goodness
> >    in terms of sleep and wakeup latencies.
> > 2) The above, and also accounted as such in the iowait stats.
> >
> > The current ->in_iowait covers both, this series splits it into two types
> > of state so that each can be controlled seperately.
>
> Yeah, but *WHY* !?!? I have some vague memories from last time around,
> but patches should really keep this information.
>
> > Patches 1..3 are prep patches, changing the type of
> > task_struct->nr_iowait and adding helpers to manipulate the iowait counts.
> >
> > Patch 4 does the actual splitting.
> >
> > This has been sitting for a while, would be nice to get this queued up
> > for 6.12. Comments welcome!
>
> Ufff, and all this because menu-governor does something insane :-(
>
> Rafael, why can't we simply remove this from menu?

Same reason as before: people use it and refuse to stop.

But this is mostly about the schedutil cpufreq governor that uses
iowait boosting.