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McKenney" , Joel Fernandes , Qais Yousef , Xuewen Yan , kuyo chang , hupu , Zhan Xusheng , "zhidao su (Xiaomi)" , Hui Su , "Shubhang Kaushik (Ampere)" , kernel-team@android.com Subject: Re: [PATCH v33 1/7] sched/psi: Preserve sleep-persistent PSI flags on off-CPU sleeping dequeues Message-ID: <20261024114422.GA6775@noisy.programming.kicks-ass.net> References: <20261023220431.1106611-1-jstultz@google.com> <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 In-Reply-To: <20261023220431.1106611-2-jstultz@google.com> On Fri, Oct 23, 2026 at 10:04:12PM +0000, John Stultz wrote: > diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h > index ebe0a7765f98e..20820fe1021a1 100644 > --- a/kernel/sched/stats.h > +++ b/kernel/sched/stats.h > @@ -175,12 +175,28 @@ static inline void psi_dequeue(struct task_struct *p, int flags) > * Do nothing here. > * > * In the SCHED_PROXY_EXECUTION case we may do sleeping > - * dequeues that are not followed by a task switch, so check > - * TSK_ONCPU is set to ensure the task switch is imminent. > - * Otherwise clear the flags as usual. > + * dequeues that are not followed by a task switch. If TSK_ONCPU > + * is not set (meaning we already switched away while the task > + * stayed on the rq as a blocked donor), handle the sleeping > + * state transition here so sleep-persistent states (TSK_MEMSTALL, > + * TSK_IOWAIT) are preserved. > */ > - if ((flags & DEQUEUE_SLEEP) && (p->psi_flags & TSK_ONCPU)) > + if (flags & DEQUEUE_SLEEP) { > + int clear = TSK_RUNNING, set = 0; > + > + if (p->psi_flags & TSK_ONCPU) > + return; > + if (p->se.sched_delayed) > + return; Must this really be sched_delayed, that is, cannot p->is_blocked be used here? I'm trying to push sched_delayed into fair.c if at all possible. > + > + if (p->in_memstall) > + clear |= TSK_MEMSTALL_RUNNING; > + if (p->in_iowait) > + set |= TSK_IOWAIT; > + > + psi_task_change(p, clear, set); > return; > + } > > /* > * When migrating a task to another CPU, clear all psi > -- > 2.56.0.257.gf7497c7d27-goog >