From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from merlin.infradead.org ([205.233.59.134]:52234 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750767AbeEIKz0 (ORCPT ); Wed, 9 May 2018 06:55:26 -0400 Date: Wed, 9 May 2018 12:55:05 +0200 From: Peter Zijlstra To: Johannes Weiner Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, cgroups@vger.kernel.org, Ingo Molnar , Andrew Morton , Tejun Heo , Balbir Singh , Mike Galbraith , Oliver Yang , Shakeel Butt , xxx xxx , Taras Kondratiuk , Daniel Walker , Vinayak Menon , Ruslan Ruslichenko , kernel-team@fb.com Subject: Re: [PATCH 6/7] psi: pressure stall information for CPU, memory, and IO Message-ID: <20180509105505.GQ12217@hirez.programming.kicks-ass.net> References: <20180507210135.1823-1-hannes@cmpxchg.org> <20180507210135.1823-7-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180507210135.1823-7-hannes@cmpxchg.org> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Mon, May 07, 2018 at 05:01:34PM -0400, Johannes Weiner wrote: > @@ -28,10 +28,14 @@ static inline int sched_info_on(void) > return 1; > #elif defined(CONFIG_TASK_DELAY_ACCT) > extern int delayacct_on; > - return delayacct_on; > -#else > - return 0; > + if (delayacct_on) > + return 1; > +#elif defined(CONFIG_PSI) > + extern int psi_disabled; > + if (!psi_disabled) > + return 1; > #endif > + return 0; > } > diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h > index 8aea199a39b4..cb4a68bcf37a 100644 > --- a/kernel/sched/stats.h > +++ b/kernel/sched/stats.h > @@ -55,12 +55,90 @@ static inline void rq_sched_info_depart (struct rq *rq, unsigned long long delt > # define schedstat_val_or_zero(var) 0 > #endif /* CONFIG_SCHEDSTATS */ > > +#ifdef CONFIG_PSI > +/* > + * PSI tracks state that persists across sleeps, such as iowaits and > + * memory stalls. As a result, it has to distinguish between sleeps, > + * where a task's runnable state changes, and requeues, where a task > + * and its state are being moved between CPUs and runqueues. > + */ > +static inline void psi_enqueue(struct task_struct *p, u64 now) > +{ > + int clear = 0, set = TSK_RUNNING; > + > + if (p->state == TASK_RUNNING || p->sched_psi_wake_requeue) { > + if (p->flags & PF_MEMSTALL) > + set |= TSK_MEMSTALL; > + p->sched_psi_wake_requeue = 0; > + } else { > + if (p->in_iowait) > + clear |= TSK_IOWAIT; > + } > + > + psi_task_change(p, now, clear, set); > +} > +static inline void psi_dequeue(struct task_struct *p, u64 now) > +{ > + int clear = TSK_RUNNING, set = 0; > + > + if (p->state == TASK_RUNNING) { > + if (p->flags & PF_MEMSTALL) > + clear |= TSK_MEMSTALL; > + } else { > + if (p->in_iowait) > + set |= TSK_IOWAIT; > + } > + > + psi_task_change(p, now, clear, set); > +} > +static inline void psi_ttwu_dequeue(struct task_struct *p) > +{ > + /* > + * Is the task being migrated during a wakeup? Make sure to > + * deregister its sleep-persistent psi states from the old > + * queue, and let psi_enqueue() know it has to requeue. > + */ > + if (unlikely(p->in_iowait || (p->flags & PF_MEMSTALL))) { > + struct rq_flags rf; > + struct rq *rq; > + int clear = 0; > + > + if (p->in_iowait) > + clear |= TSK_IOWAIT; > + if (p->flags & PF_MEMSTALL) > + clear |= TSK_MEMSTALL; > + > + rq = __task_rq_lock(p, &rf); > + update_rq_clock(rq); > + psi_task_change(p, rq_clock(rq), clear, 0); > + p->sched_psi_wake_requeue = 1; > + __task_rq_unlock(rq, &rf); > + } > +} That all seems to be missing psi_disabled tests.. Yes I know it's burried down in psi_task_change() somewhere, but that's really (too) late. (also, you seem to be conserving whitespace; typically we have an empty lines between functions)