From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0029EECDFB1 for ; Tue, 17 Jul 2018 10:04:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9A45E2148E for ; Tue, 17 Jul 2018 10:04:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Hik9Zahr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9A45E2148E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729983AbeGQKfr (ORCPT ); Tue, 17 Jul 2018 06:35:47 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:46912 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729656AbeGQKfr (ORCPT ); Tue, 17 Jul 2018 06:35:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=iXNnyF2ef2ZgbJomMol+/cweHoUkF/XCw3sPJXTZ2R4=; b=Hik9ZahreQ2sr0HCHcXj5f+3L 0ddtuhzzkZccZTR88SQVLdALCJNildsXLwTCHP60RBngAlJm+EZByVl+AMe9NqL4gUBujykYzKBt+ ThEL/uK38aDGcrSqmvbK1S4mpMnrbvhLiOWPX+rt06J8JbMk6bEnePgmMsOOuCxE00PU6WK//laRG GYtlLmXJkSXxAKHDrdmPeZXC/MI4u1sIpnZgK4NLuS5N8NHGowgBiftKufUSyMEG8cPiVJvK6i8oz Vj+9EJA5nAvdGOfo/YbQkCK4tW3Js4G2HpUDVVI20MY3KWqH1uhftuTPMtFEDahPzKnWxBTqO9soZ w1X/sZhkw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1ffMpi-0003Bo-1Q; Tue, 17 Jul 2018 10:03:50 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C38D520289332; Tue, 17 Jul 2018 12:03:47 +0200 (CEST) Date: Tue, 17 Jul 2018 12:03:47 +0200 From: Peter Zijlstra To: Johannes Weiner Cc: Ingo Molnar , Andrew Morton , Linus Torvalds , Tejun Heo , Suren Baghdasaryan , Vinayak Menon , Christopher Lameter , Mike Galbraith , Shakeel Butt , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 08/10] psi: pressure stall information for CPU, memory, and IO Message-ID: <20180717100347.GD2494@hirez.programming.kicks-ass.net> References: <20180712172942.10094-1-hannes@cmpxchg.org> <20180712172942.10094-9-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180712172942.10094-9-hannes@cmpxchg.org> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 12, 2018 at 01:29:40PM -0400, Johannes Weiner wrote: > +static void time_state(struct psi_resource *res, int state, u64 now) > +{ > + if (res->state != PSI_NONE) { > + bool was_full = res->state == PSI_FULL; > + > + res->times[was_full] += now - res->state_start; > + } > + if (res->state != state) > + res->state = state; > + if (res->state != PSI_NONE) > + res->state_start = now; > +} > + > +static void psi_group_change(struct psi_group *group, int cpu, u64 now, > + unsigned int clear, unsigned int set) > +{ > + enum psi_state state = PSI_NONE; > + struct psi_group_cpu *groupc; > + unsigned int *tasks; > + unsigned int to, bo; > + > + groupc = per_cpu_ptr(group->cpus, cpu); > + tasks = groupc->tasks; > + > + /* Update task counts according to the set/clear bitmasks */ > + for (to = 0; (bo = ffs(clear)); to += bo, clear >>= bo) { > + int idx = to + (bo - 1); > + > + if (tasks[idx] == 0 && !psi_bug) { > + printk_deferred(KERN_ERR "psi: task underflow! cpu=%d idx=%d tasks=[%u %u %u] clear=%x set=%x\n", > + cpu, idx, tasks[0], tasks[1], tasks[2], > + clear, set); > + psi_bug = 1; > + } > + tasks[idx]--; > + } > + for (to = 0; (bo = ffs(set)); to += bo, set >>= bo) > + tasks[to + (bo - 1)]++; > + > + /* Time in which tasks wait for the CPU */ > + state = PSI_NONE; > + if (tasks[NR_RUNNING] > 1) > + state = PSI_SOME; > + time_state(&groupc->res[PSI_CPU], state, now); > + > + /* Time in which tasks wait for memory */ > + state = PSI_NONE; > + if (tasks[NR_MEMSTALL]) { > + if (!tasks[NR_RUNNING] || > + (cpu_curr(cpu)->flags & PF_MEMSTALL)) > + state = PSI_FULL; > + else > + state = PSI_SOME; > + } > + time_state(&groupc->res[PSI_MEM], state, now); > + > + /* Time in which tasks wait for IO */ > + state = PSI_NONE; > + if (tasks[NR_IOWAIT]) { > + if (!tasks[NR_RUNNING]) > + state = PSI_FULL; > + else > + state = PSI_SOME; > + } > + time_state(&groupc->res[PSI_IO], state, now); > + > + /* Time in which tasks are non-idle, to weigh the CPU in summaries */ > + if (groupc->nonidle) > + groupc->nonidle_time += now - groupc->nonidle_start; > + groupc->nonidle = tasks[NR_RUNNING] || > + tasks[NR_IOWAIT] || tasks[NR_MEMSTALL]; > + if (groupc->nonidle) > + groupc->nonidle_start = now; > + > + /* Kick the stats aggregation worker if it's gone to sleep */ > + if (!delayed_work_pending(&group->clock_work)) > + schedule_delayed_work(&group->clock_work, PSI_FREQ); > +} > + > +void psi_task_change(struct task_struct *task, u64 now, int clear, int set) > +{ > + int cpu = task_cpu(task); > + > + if (psi_disabled) > + return; > + > + if (!task->pid) > + return; > + > + if (((task->psi_flags & set) || > + (task->psi_flags & clear) != clear) && > + !psi_bug) { > + printk_deferred(KERN_ERR "psi: inconsistent task state! task=%d:%s cpu=%d psi_flags=%x clear=%x set=%x\n", > + task->pid, task->comm, cpu, > + task->psi_flags, clear, set); > + psi_bug = 1; > + } > + > + task->psi_flags &= ~clear; > + task->psi_flags |= set; > + > + psi_group_change(&psi_system, cpu, now, clear, set); > +} > +/* > + * 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, bool wakeup) > +{ > + int clear = 0, set = TSK_RUNNING; > + > + if (psi_disabled) > + return; > + > + if (!wakeup || p->sched_psi_wake_requeue) { > + if (p->flags & PF_MEMSTALL) > + set |= TSK_MEMSTALL; > + if (p->sched_psi_wake_requeue) > + 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, bool sleep) > +{ > + int clear = TSK_RUNNING, set = 0; > + > + if (psi_disabled) > + return; > + > + if (!sleep) { > + if (p->flags & PF_MEMSTALL) > + clear |= TSK_MEMSTALL; > + } else { > + if (p->in_iowait) > + set |= TSK_IOWAIT; > + } > + > + psi_task_change(p, now, clear, set); > +} This is still a scary amount of accounting; not to mention you'll be adding O(cgroup-depth) to this in a later patch. Where are the performance numbers for all this?