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Sun, 25 Oct 2026 22:16:16 -0700 (PDT) Received: from osman.mioffice.cn ([43.224.245.178]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3adebfa4102sm6881508a91.12.2026.10.25.22.16.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Oct 2026 22:16:16 -0700 (PDT) From: Zhan Xusheng To: jstultz@google.com Cc: peterz@infradead.org, hannes@cmpxchg.org, surenb@google.com, mingo@redhat.com, kprateek.nayak@amd.com, arighi@nvidia.com, stevensd@google.com, tglx@linutronix.de, juri.lelli@redhat.com, vincent.guittot@linaro.org, vschneid@redhat.com, suleiman@google.com, Metin.Kaya@arm.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, zezeozue@google.com, longman@redhat.com, boqun.feng@gmail.com, paulmck@kernel.org, joelagnelf@nvidia.com, qyousef@layalina.io, xuewen.yan94@gmail.com, kuyo.chang@mediatek.com, hupu.gm@gmail.com, soolaugust@gmail.com, sh_def@163.com, sh@gentwo.org, kernel-team@android.com, linux-kernel@vger.kernel.org, zhanxusheng@xiaomi.com, Zhan Xusheng Subject: Re: [PATCH v33 1/7] sched/psi: Preserve sleep-persistent PSI flags on off-CPU sleeping dequeues Date: Mon, 26 Oct 2026 13:16:05 +0800 Message-ID: <20261026051605.1997313-1-zhanxusheng1024@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261023220431.1106611-2-jstultz@google.com> References: <20261023220431.1106611-2-jstultz@google.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8bit Hi John, On Fri, Oct 23, 2026 at 10:04:12PM +0000, John Stultz wrote: > + if (p->in_memstall) > + clear |= TSK_MEMSTALL_RUNNING; > + if (p->in_iowait) > + set |= TSK_IOWAIT; > + > + psi_task_change(p, clear, set); In this case psi_task_switch() also clears wake_clock when the task going to sleep is the psi_avgs_work() worker, so the worker doesn't re-arm its own work. psi_task_change() always passes wake_clock=true, so that check is lost here. The worker can get here: psi_avgs_work() takes group->avgs_lock, which psi_show(), psi_trigger_create() and psi_trigger_destroy() can hold while sleeping, so it can block on a sleeping owner and be dequeued through this branch. TSK_ONCPU is already clear by then, since find_proxy_task() doesn't park a chain that contains curr. The cost is an extra aggregation period, not the ping-pong described in psi_task_switch(), but it keeps the averaging clock from shutting off while idle. Should this branch do the same PF_WQ_WORKER check? Thanks, Zhan Xusheng