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 04708C433EF for ; Mon, 25 Apr 2022 11:39:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6F2826B0074; Mon, 25 Apr 2022 07:39:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6A1E16B0075; Mon, 25 Apr 2022 07:39:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5693C6B0078; Mon, 25 Apr 2022 07:39:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id 48EBA6B0074 for ; Mon, 25 Apr 2022 07:39:17 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 1C88324E65 for ; Mon, 25 Apr 2022 11:39:17 +0000 (UTC) X-FDA: 79395205554.09.10C5C0E Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf05.hostedemail.com (Postfix) with ESMTP id CA1CF10003C for ; Mon, 25 Apr 2022 11:39:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650886755; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=dWekVSPYd8xYAt3O60VkUDiNCfHG1joVEXBu5UZWkrw=; b=YN8m6mLLkfgMgH7PdaccLvnQQedjuNmnWN95k97ZHgIzlbVK3y0QzwTv1JtBxlBhOWORPg WEoeeD+4isws/fxVlYl7ZxCxDng51iqykZYew/Mah2A6QZ3wFruHaAC801gNWzN6FGZT2K BZ1q9iUXNb5isWi86jZwQzuzy5YXMkg= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-266-dAyQmcyRM8ixpriHngQL2w-1; Mon, 25 Apr 2022 07:39:14 -0400 X-MC-Unique: dAyQmcyRM8ixpriHngQL2w-1 Received: by mail-wm1-f70.google.com with SMTP id d13-20020a05600c3acd00b0038ff865c043so10176117wms.3 for ; Mon, 25 Apr 2022 04:39:14 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=dWekVSPYd8xYAt3O60VkUDiNCfHG1joVEXBu5UZWkrw=; b=JUoRperOw75WKh4cx35/5GKstI7wIfiDmaicq25UO6gucXvkgIttlnUqJB8EAHggwa TR1HXfIOA2xHM2rRxLMVLb0rc8KNqvhPryGXFd4L6Feijn5lKqKjC2tZMhhM939hgJ3k EG62UHYROUWLZ7nJJMSdqjdRFfkM/Ia6rQ9tGyFzO/Le68Fk530QDPY7eiiwnDlQqvbB kkoaM/73MlFb1xmM1cventIzT8ZCUB40+kP8cQKfVLf6qJg1PpDTnmG+Dkk9HOPScMRm JPIIpDXZ2SXFwAcJgDexx0Uncbht//IjZWx3xmQ/s+Ga5DOobbOqNsv0QgIEgjXlXSjv fxCw== X-Gm-Message-State: AOAM531MM0f3SQKPq5gn2p4dX5K1UM4gJKQ7EZhs30we2Y02ChUf7JXW GL9q4PwMl2zHSgtxZzK/hciM+DWhViUA4VPF1v1/D2UcmxL5zXwReNByW4eGEDJC8P+10UpW8+n pYOT0OvFDfg== X-Received: by 2002:adf:f710:0:b0:20a:e189:9983 with SMTP id r16-20020adff710000000b0020ae1899983mr133537wrp.24.1650886753362; Mon, 25 Apr 2022 04:39:13 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwq4QRElPhL8bLGVswnlIMjcwsK192ldTpRUzZ0gIm2L1nYcCNVDuB8lSD6IXZRABNNdhtiOQ== X-Received: by 2002:adf:f710:0:b0:20a:e189:9983 with SMTP id r16-20020adff710000000b0020ae1899983mr133512wrp.24.1650886753070; Mon, 25 Apr 2022 04:39:13 -0700 (PDT) Received: from localhost (cpc111743-lutn13-2-0-cust979.9-3.cable.virginm.net. [82.17.115.212]) by smtp.gmail.com with ESMTPSA id j39-20020a05600c1c2700b00393ee3deaf1sm1758378wms.9.2022.04.25.04.39.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Apr 2022 04:39:12 -0700 (PDT) Date: Mon, 25 Apr 2022 12:39:09 +0100 From: Aaron Tomlin To: Christoph Lameter Cc: frederic@kernel.org, mtosatti@redhat.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: [RFC PATCH v3] tick/sched: Ensure quiet_vmstat() is called when the idle tick was stopped too Message-ID: <20220425113909.u3smtztp66svlw4o@ava.usersys.com> X-PGP-Key: http://pgp.mit.edu/pks/lookup?search=atomlin%40redhat.com X-PGP-Fingerprint: 7906 84EB FA8A 9638 8D1E 6E9B E2DE 9658 19CC 77D6 References: <20220422193647.3808657-1-atomlin@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Stat-Signature: fnmkzi4bzz8sejbf6hpxhxkqx6gz6uzu X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: CA1CF10003C X-Rspam-User: Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=YN8m6mLL; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf05.hostedemail.com: domain of atomlin@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=atomlin@redhat.com X-HE-Tag: 1650886750-321288 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 Mon 2022-04-25 09:23 +0200, Christoph Lameter wrote: > On Fri, 22 Apr 2022, Aaron Tomlin wrote: > > > A customer provided some evidence which indicates that the idle tick was > > stopped; albeit, CPU-specific vmstat counters still remained populated. > > Thus one can only assume quiet_vmstat() was not invoked on return to the > > idle loop. > > Could we *always* fold the vmstat counters when entering idle mode? That > would make the logic less complicated. There is nothing else to do since > we are entering an idle state and if there are any counter deltas then we > have the time to process them. This may also decrease the time that > deltas exist significantly and an idle system will have accurate vmstat > counters. Hi Christoph, Thank you for your feedback. Yes, in the context of nohz, this patch should ensure it, if required, when the idle tick is to be stopped. Kind regards, -- Aaron Tomlin