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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE008C4332F for ; Wed, 14 Dec 2022 13:18:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0DC418E0003; Wed, 14 Dec 2022 08:18:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 08B148E0002; Wed, 14 Dec 2022 08:18:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E94A58E0003; Wed, 14 Dec 2022 08:18:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id D99968E0002 for ; Wed, 14 Dec 2022 08:18:45 -0500 (EST) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 95942140B79 for ; Wed, 14 Dec 2022 13:18:45 +0000 (UTC) X-FDA: 80240966610.30.8201A61 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf05.hostedemail.com (Postfix) with ESMTP id E6F95100006 for ; Wed, 14 Dec 2022 13:18:43 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=sVXi2uB7; spf=pass (imf05.hostedemail.com: domain of frederic@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=frederic@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1671023924; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=CxXc3PKNe1+l8vLZ5VYGIVok8hwCQvdjrhwgVja1WIY=; b=5W5eM6UPSlCm73EkYTlQ+UoEuv9IGUiU8tQVX5anoiDBckUpoH73OWMCqUTWrY5Kil9yMt lGFXsmrPvB1vsNEG2m8tx7EZYlB923MxQ5Q413AUAAR2XmO0/dKlHt2NMVdZbqQ9/5Ifq6 LYAcJ5BDvg+uV/XmGIqwRzcZjM5CDvU= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=sVXi2uB7; spf=pass (imf05.hostedemail.com: domain of frederic@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=frederic@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1671023924; a=rsa-sha256; cv=none; b=efzwpcg08Loypo+wkJz40o213ASUMVNTUCzC68NsYYuPwVr6+l3IKLDSn7IGGSAofwpeST 4k+3WHi0qOp0CtT3wKO3fjDrrRylcaFQy47nQjtbOr3IalXIDzGxCk19iqkiCjjvkMJM64 ZQ4Ffl4PE345uBGcctR9Zgw5tKEcZrs= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id F1D9161843; Wed, 14 Dec 2022 13:18:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D69D5C433EF; Wed, 14 Dec 2022 13:18:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671023922; bh=vUEUw7umkHcdN8/poSpqNEUmzIsAMybBL8IL/dAeuUU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sVXi2uB7BtOjWKiCScn5bL9wd1ewcVR4gJUZN10rI/+X+ZA01cOJIbqR6STKAvEKz iHEx+hSxSwpam3bUActYuIbvmF/3ejyT+QjK6j4nzbUCkt9vrUzn5dHHxvSSjwBdCa 1wZ4+QXEoW7AddsbPvZft77G/y4jMFapXIAC+n06Yj/fUfkBXIjNC52Pqx9c2Lh/WN ZIXeeVnplrYXgBItr+zqv5B31FPHHludoL9GiPDmu2Wh+RIrtsJ8FnfnzDORMHGrun x8nU5igAlnMZXJvaItaPy9oXl77tlB3iWbj5FTeUtM39p65qyOZRQoBg23ZUhf4wEC l9GGMhajS+vMw== Date: Wed, 14 Dec 2022 14:18:39 +0100 From: Frederic Weisbecker To: Marcelo Tosatti Cc: atomlin@redhat.com, cl@linux.com, tglx@linutronix.de, mingo@kernel.org, peterz@infradead.org, pauld@redhat.com, neelx@redhat.com, oleksandr@natalenko.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v9 3/5] mm/vmstat: manage per-CPU stats from CPU context when NOHZ full Message-ID: <20221214131839.GE1930067@lothringen> References: <20221206161826.698593151@redhat.com> <20221206162416.474800121@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221206162416.474800121@redhat.com> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: E6F95100006 X-Stat-Signature: jnup5tgy4autk11xfox4bwgzhn9susas X-Rspam-User: X-HE-Tag: 1671023923-35242 X-HE-Meta: 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 IPOdHGPD ggBa0lFtgZtDWWkL/y4cBGRSwAVaw+T+DfxAg X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Dec 06, 2022 at 01:18:29PM -0300, Marcelo Tosatti wrote: > For nohz full CPUs, manage per-CPU stat syncing from CPU context: > start delayed work when marking per-CPU vmstat dirty. > > When returning to userspace, fold the stats and cancel the delayed work. > > When entering idle, only fold the stats. The changelog still misses the reason behind the changes. > @@ -195,9 +196,24 @@ void fold_vm_numa_events(void) > > #ifdef CONFIG_SMP > static DEFINE_PER_CPU_ALIGNED(bool, vmstat_dirty); > +static DEFINE_PER_CPU(struct delayed_work, vmstat_work); > +int sysctl_stat_interval __read_mostly = HZ; > > static inline void vmstat_mark_dirty(void) > { > + int cpu = smp_processor_id(); > + > + if (tick_nohz_full_cpu(cpu) && !this_cpu_read(vmstat_dirty)) { > + struct delayed_work *dw; > + > + dw = &per_cpu(vmstat_work, cpu); this_cpu_ptr() > + if (!delayed_work_pending(dw)) { > + unsigned long delay; > + > + delay = round_jiffies_relative(sysctl_stat_interval); > + queue_delayed_work_on(cpu, mm_percpu_wq, dw, delay); > + } > + } > this_cpu_write(vmstat_dirty, true); > } > > @@ -1973,21 +1986,27 @@ static void vmstat_update(struct work_st > * until the diffs stay at zero. The function is used by NOHZ and can only be > * invoked when tick processing is not active. > */ > -void quiet_vmstat(void) > +void quiet_vmstat(bool user) > { > + struct delayed_work *dw; > + > if (system_state != SYSTEM_RUNNING) > return; > > if (!is_vmstat_dirty()) > return; > > + refresh_cpu_vm_stats(false); > + > + if (!user) > + return; > /* > - * Just refresh counters and do not care about the pending delayed > - * vmstat_update. It doesn't fire that often to matter and canceling > - * it would be too expensive from this path. > - * vmstat_shepherd will take care about that for us. > + * If the tick is stopped, cancel any delayed work to avoid > + * interruptions to this CPU in the future. > */ > - refresh_cpu_vm_stats(false); > + dw = &per_cpu(vmstat_work, smp_processor_id()); this_cpu_ptr() Thanks. > + if (delayed_work_pending(dw)) > + cancel_delayed_work(dw); > } > > /*