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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3BF3DC00140 for ; Wed, 24 Aug 2022 10:46:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234747AbiHXKqw (ORCPT ); Wed, 24 Aug 2022 06:46:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237138AbiHXKqe (ORCPT ); Wed, 24 Aug 2022 06:46:34 -0400 Received: from mail-ed1-x52a.google.com (mail-ed1-x52a.google.com [IPv6:2a00:1450:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 875AE8F95C for ; Wed, 24 Aug 2022 03:46:05 -0700 (PDT) Received: by mail-ed1-x52a.google.com with SMTP id z2so21513215edc.1 for ; Wed, 24 Aug 2022 03:46:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20210112.gappssmtp.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc; bh=Aj++Fk/W1JhvrURKcMUAUKoprlyW7CHD6tgqm6w3ip8=; b=6Iyv3/J5KocnAeNqHO+9drc0u5aILR13sqA6Kvkg5zjYCKXLwJp7Cu69hxIFDTViq+ HZYQlApQOCAUdvrC9loeA0eKBfIGGnditmSzzpOZ90vXY1TuDg3lsp31JoFuqP0/wSxU XSX4NHtEDrxhXz5fAmvszL3QwtVPl4/KNvLyXFAGbl+mLr5I/5wj2uzT7zmP6iMEYfIJ 9vo0CLZE+RH2KthBtZt8o0SxWYfNCTmfSjT2pcY6uS8qAGOOCRMdyXDM/SlcpnzLMib+ au4RGN94O395cioi2TT229XLk3Lnw/U/OjFCbsyXY5/YzL0Dm8dJTgMarbwsOWWBdf1o S4BA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc; bh=Aj++Fk/W1JhvrURKcMUAUKoprlyW7CHD6tgqm6w3ip8=; b=jP+AZlmRmluyCP4cD0E1f1Dg9Sm0BgZcDeIH792vjbJ55XGweBrnb6a9iExindIatK RgpTw3l6sH/cOQWoyzNaoxWFKTNiyKBX4a6tCJEk3oaU+4NzAm7AEwIPG7zJOrgN8VvO w9PljNLKzHXaXZp+KD5tCPo7otVWJGaE8h608jUiYs6KuJBdzlbbzGjTszFBDtvWi9m2 7yLGkhAQJZzbh4lBUFPEeyKT45pofrHwUp3Z9Dpf+Jc7v/p7oPVWs12ZVeag6oduv6+I OlcO76s2xe7XP8uBSEzk0YFvastNe3DTHRcfG5nh0idgEnbEIqnGFOscv5ckWFqrYzNE sq/w== X-Gm-Message-State: ACgBeo3G7v25abBzXGpHpLkWd7O3EqwHLCG+hbPbMnZJOTcUeOCFReNv Vy+2TwVd1JUvNLeOWu9KeLUq6A== X-Google-Smtp-Source: AA6agR5qwKkldsOR95XGvbtkAB2O9Mwd/1Y/pKoFJTvq65sd3Go0/YjkckRvGYFCO0Alrei9s0xxYA== X-Received: by 2002:a05:6402:43c6:b0:43d:79a6:4e32 with SMTP id p6-20020a05640243c600b0043d79a64e32mr6857725edc.281.1661337963817; Wed, 24 Aug 2022 03:46:03 -0700 (PDT) Received: from localhost ([2a02:8070:6389:a4c0:2ca9:6d59:782b:fff3]) by smtp.gmail.com with ESMTPSA id e12-20020a056402330c00b00445f2dc2901sm2889216eda.21.2022.08.24.03.46.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Aug 2022 03:46:03 -0700 (PDT) Date: Wed, 24 Aug 2022 06:46:02 -0400 From: Johannes Weiner To: Chengming Zhou Cc: tj@kernel.org, mkoutny@suse.com, surenb@google.com, gregkh@linuxfoundation.org, corbet@lwn.net, mingo@redhat.com, peterz@infradead.org, songmuchun@bytedance.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 07/10] sched/psi: add PSI_IRQ to track IRQ/SOFTIRQ pressure Message-ID: References: <20220824081829.33748-1-zhouchengming@bytedance.com> <20220824081829.33748-8-zhouchengming@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220824081829.33748-8-zhouchengming@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 24, 2022 at 04:18:26PM +0800, Chengming Zhou wrote: > @@ -903,6 +903,36 @@ void psi_task_switch(struct task_struct *prev, struct task_struct *next, > } > } > > +#ifdef CONFIG_IRQ_TIME_ACCOUNTING > +void psi_account_irqtime(struct task_struct *task, u32 delta) > +{ > + int cpu = task_cpu(task); > + void *iter = NULL; > + struct psi_group *group; > + struct psi_group_cpu *groupc; > + u64 now; > + > + if (!task->pid) > + return; > + > + now = cpu_clock(cpu); > + > + while ((group = iterate_groups(task, &iter))) { > + groupc = per_cpu_ptr(group->pcpu, cpu); > + > + write_seqcount_begin(&groupc->seq); > + > + record_times(groupc, now); > + groupc->times[PSI_IRQ_FULL] += delta; > + > + write_seqcount_end(&groupc->seq); > + > + if (group->poll_states & (1 << PSI_IRQ_FULL)) > + psi_schedule_poll_work(group, 1); > + } Shouldn't this kick avgs_work too? If the CPU is otherwise idle, times[PSI_IRQ_FULL] would overflow after two missed averaging runs. avgs_work should probably also self-perpetuate when PSI_IRQ_FULL is in changed_states. (Looking at that code, I think it can be simplified: delete nonidle and do `if (changed_states) schedule_delayed_work()`.) From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Weiner Subject: Re: [PATCH v3 07/10] sched/psi: add PSI_IRQ to track IRQ/SOFTIRQ pressure Date: Wed, 24 Aug 2022 06:46:02 -0400 Message-ID: References: <20220824081829.33748-1-zhouchengming@bytedance.com> <20220824081829.33748-8-zhouchengming@bytedance.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20210112.gappssmtp.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc; bh=Aj++Fk/W1JhvrURKcMUAUKoprlyW7CHD6tgqm6w3ip8=; b=6Iyv3/J5KocnAeNqHO+9drc0u5aILR13sqA6Kvkg5zjYCKXLwJp7Cu69hxIFDTViq+ HZYQlApQOCAUdvrC9loeA0eKBfIGGnditmSzzpOZ90vXY1TuDg3lsp31JoFuqP0/wSxU XSX4NHtEDrxhXz5fAmvszL3QwtVPl4/KNvLyXFAGbl+mLr5I/5wj2uzT7zmP6iMEYfIJ 9vo0CLZE+RH2KthBtZt8o0SxWYfNCTmfSjT2pcY6uS8qAGOOCRMdyXDM/SlcpnzLMib+ au4RGN94O395cioi2TT229XLk3Lnw/U/OjFCbsyXY5/YzL0Dm8dJTgMarbwsOWWBdf1o S4BA== Content-Disposition: inline In-Reply-To: <20220824081829.33748-8-zhouchengming-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Chengming Zhou Cc: tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, mkoutny-IBi9RG/b67k@public.gmane.org, surenb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, corbet-T1hC0tSOHrs@public.gmane.org, mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On Wed, Aug 24, 2022 at 04:18:26PM +0800, Chengming Zhou wrote: > @@ -903,6 +903,36 @@ void psi_task_switch(struct task_struct *prev, struct task_struct *next, > } > } > > +#ifdef CONFIG_IRQ_TIME_ACCOUNTING > +void psi_account_irqtime(struct task_struct *task, u32 delta) > +{ > + int cpu = task_cpu(task); > + void *iter = NULL; > + struct psi_group *group; > + struct psi_group_cpu *groupc; > + u64 now; > + > + if (!task->pid) > + return; > + > + now = cpu_clock(cpu); > + > + while ((group = iterate_groups(task, &iter))) { > + groupc = per_cpu_ptr(group->pcpu, cpu); > + > + write_seqcount_begin(&groupc->seq); > + > + record_times(groupc, now); > + groupc->times[PSI_IRQ_FULL] += delta; > + > + write_seqcount_end(&groupc->seq); > + > + if (group->poll_states & (1 << PSI_IRQ_FULL)) > + psi_schedule_poll_work(group, 1); > + } Shouldn't this kick avgs_work too? If the CPU is otherwise idle, times[PSI_IRQ_FULL] would overflow after two missed averaging runs. avgs_work should probably also self-perpetuate when PSI_IRQ_FULL is in changed_states. (Looking at that code, I think it can be simplified: delete nonidle and do `if (changed_states) schedule_delayed_work()`.)