Received-SPF: pass (google.com: domain of linux-kernel+bounces-106423-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Precedence: bulk
MIME-Version: 1.0
References: <20240304201625.100619-1-christian.loehle@arm.com>
 <20240304201625.100619-3-christian.loehle@arm.com> <CAJZ5v0gMni0QJTBJXoVOav=kOtQ9W--NyXAgq+dXA+m-bciG8w@mail.gmail.com>
 <5060c335-e90a-430f-bca5-c0ee46a49249@arm.com>
In-Reply-To: <5060c335-e90a-430f-bca5-c0ee46a49249@arm.com>
From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Mon, 18 Mar 2024 18:08:44 +0100
Message-ID: <CAJZ5v0janPrWRkjcLkFeP9gmTC-nVRF-NQCh6CTET6ENy-_knQ@mail.gmail.com>
Subject: Re: [RFC PATCH 2/2] cpufreq/schedutil: Remove iowait boost
To: Christian Loehle <christian.loehle@arm.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>, linux-kernel@vger.kernel.org, peterz@infradead.org, 
	juri.lelli@redhat.com, mingo@redhat.com, dietmar.eggemann@arm.com, 
	vschneid@redhat.com, vincent.guittot@linaro.org, Johannes.Thumshirn@wdc.com, 
	adrian.hunter@intel.com, ulf.hansson@linaro.org, andres@anarazel.de, 
	asml.silence@gmail.com, linux-pm@vger.kernel.org, linux-block@vger.kernel.org, 
	io-uring@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Mon, Mar 18, 2024 at 5:40=E2=80=AFPM Christian Loehle
<christian.loehle@arm.com> wrote:
>
> On 18/03/2024 14:07, Rafael J. Wysocki wrote:
> > On Mon, Mar 4, 2024 at 9:17=E2=80=AFPM Christian Loehle
> > <christian.loehle@arm.com> wrote:
> >>
> >> The previous commit provides a new cpu_util_cfs_boost_io interface for
> >> schedutil which uses the io boosted utilization of the per-task
> >> tracking strategy. Schedutil iowait boosting is therefore no longer
> >> necessary so remove it.
> >
> > I'm wondering about the cases when schedutil is used without EAS.
> >
> > Are they still going to be handled as before after this change?
>
> Well they should still get boosted (under the new conditions) and accordi=
ng
> to my tests that does work.

OK

> Anything in particular you're worried about?

It is not particularly clear to me how exactly the boost is taken into
account without EAS.

> So in terms of throughput I see similar results with EAS and CAS+sugov.
> I'm happy including numbers in the cover letter for future versions, too.
> So far my intuition was that nobody would care enough to include them
> (as long as it generally still works).

Well, IMV clear understanding of the changes is more important.