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 CE02FC433F5 for ; Mon, 25 Apr 2022 07:23:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3A86C8D0009; Mon, 25 Apr 2022 03:23:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3311E8D0006; Mon, 25 Apr 2022 03:23:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1D17E8D0009; Mon, 25 Apr 2022 03:23:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id 0AF2B8D0006 for ; Mon, 25 Apr 2022 03:23:04 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id C86E22269C for ; Mon, 25 Apr 2022 07:23:03 +0000 (UTC) X-FDA: 79394559846.23.C961767 Received: from gentwo.de (gentwo.de [161.97.139.209]) by imf18.hostedemail.com (Postfix) with ESMTP id 994F51C003B for ; Mon, 25 Apr 2022 07:22:59 +0000 (UTC) Received: by gentwo.de (Postfix, from userid 1001) id 2A115B000C1; Mon, 25 Apr 2022 09:23:01 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by gentwo.de (Postfix) with ESMTP id 27161B00078; Mon, 25 Apr 2022 09:23:01 +0200 (CEST) Date: Mon, 25 Apr 2022 09:23:01 +0200 (CEST) From: Christoph Lameter To: Aaron Tomlin 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 In-Reply-To: <20220422193647.3808657-1-atomlin@redhat.com> Message-ID: References: <20220422193647.3808657-1-atomlin@redhat.com> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 994F51C003B X-Stat-Signature: tmoh84fsogptio1udx79df4n78tr14xx X-Rspam-User: Authentication-Results: imf18.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf18.hostedemail.com: domain of cl@gentwo.de designates 161.97.139.209 as permitted sender) smtp.mailfrom=cl@gentwo.de X-Rspamd-Server: rspam09 X-HE-Tag: 1650871379-913009 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 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.