linux-kernel - Re: [PATCH 2/2] sched_ext: Add cpuperf support

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]

Date: Tue, 2 Jul 2024 06:37:51 -1000
From: Tejun Heo <tj@...nel.org>
To: Hongyan Xia <hongyan.xia2@....com>
Cc: rafael@...nel.org, viresh.kumar@...aro.org, linux-pm@...r.kernel.org,
	void@...ifault.com, linux-kernel@...r.kernel.org,
	kernel-team@...a.com, mingo@...hat.com, peterz@...radead.org,
	David Vernet <dvernet@...a.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH 2/2] sched_ext: Add cpuperf support

Hello, Hongyan.

On Tue, Jul 02, 2024 at 11:23:58AM +0100, Hongyan Xia wrote:
> What would be really nice is to have cpufreq support in sched_ext but not
> force uclamp_enabled. But, I also think there will be people who are happy
> with the current uclamp implementation and want to just reuse it. The best
> thing is to let the loaded scheduler decide, somehow, which I don't know if
> there's an easy way to do this yet.

I don't know much about uclamp but at least from sched_ext side, it's
trivial add an ops flag for it and because we know that no tasks are on the
ext class before BPF scheduler is loaded, as long as we switch the
uclamp_enabled value while the BPF scheduler is not loaded, the uclamp
buckets should stay balanced. AFAICS, the only core change we need to make
is mooving the uclamp_enabled bool outside sched_class so that it can be
changed runtime. Is that the case or am I missing something?

Thanks.

-- 
tejun