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[141.239.149.160]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fac10e3311sm86082035ad.79.2024.07.02.09.37.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Jul 2024 09:37:53 -0700 (PDT) Sender: Tejun Heo Date: Tue, 2 Jul 2024 06:37:51 -1000 From: Tejun Heo To: Hongyan Xia Cc: rafael@kernel.org, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, void@manifault.com, linux-kernel@vger.kernel.org, kernel-team@meta.com, mingo@redhat.com, peterz@infradead.org, David Vernet , "Rafael J . Wysocki" Subject: Re: [PATCH 2/2] sched_ext: Add cpuperf support Message-ID: References: <20240619031250.2936087-1-tj@kernel.org> <20240619031250.2936087-3-tj@kernel.org> <63c76af4-6451-4d6a-8aeb-0bc4812c4101@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <63c76af4-6451-4d6a-8aeb-0bc4812c4101@arm.com> 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