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 5EF41C433EF for ; Mon, 25 Apr 2022 13:27:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DCCE26B0081; Mon, 25 Apr 2022 09:27:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D55D76B007E; Mon, 25 Apr 2022 09:27:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C1CAE6B0081; Mon, 25 Apr 2022 09:27:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id A20106B007D for ; Mon, 25 Apr 2022 09:27:08 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 780A92725F for ; Mon, 25 Apr 2022 13:27:08 +0000 (UTC) X-FDA: 79395477336.14.C027771 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) by imf02.hostedemail.com (Postfix) with ESMTP id EFDA080047 for ; Mon, 25 Apr 2022 13:27:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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; bh=H7R9p0jqKi7IyAfu9QDTZpmTUdknj0kaCCRV1aoBUQk=; b=hf1suSMghz2ceMZPIZYlFREg21 DyAubvSopa9rdwlzusFAfK1XFLaHcgnbfLL5klVqhUEq+S5TSEYikXChvvwGMmG2wQNiXjbiUoO0X TH1YgHxX3+UBU6m79HgHi4tzAXHToH9njB0IeZeU997ZydzYx0EUEodScuxmfGqjKzNcrnrBnSFza dyiCroLwfiwNLQ5tG1Z/D4KTxbMN0b5TPCdr2yGr2kO5AhZrjTrv4SQAA6BnDzjXhD3RO+T/E5Vw8 lwk460VchNXCm6R+0+GhLFcQtpoZKC+WPcn+vCM8H5mE7UeLUrPK2qgHM8b6ElVMXrdLTPMpodEVy f4ldO+FQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1niyk2-008YA6-3M; Mon, 25 Apr 2022 13:27:02 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 50130980C1C; Mon, 25 Apr 2022 15:27:00 +0200 (CEST) Date: Mon, 25 Apr 2022 15:27:00 +0200 From: Peter Zijlstra To: Christoph Lameter Cc: Aaron Tomlin , frederic@kernel.org, mtosatti@redhat.com, tglx@linutronix.de, mingo@kernel.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: <20220425132700.GK2731@worktop.programming.kicks-ass.net> References: <20220422193647.3808657-1-atomlin@redhat.com> <20220425113909.u3smtztp66svlw4o@ava.usersys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: EFDA080047 X-Stat-Signature: p3nw9o3ydohtee17gniep59twn6di9s9 X-Rspam-User: Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=desiato.20200630 header.b=hf1suSMg; spf=none (imf02.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.92.199) smtp.mailfrom=peterz@infradead.org; dmarc=none X-HE-Tag: 1650893224-115526 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, Apr 25, 2022 at 02:09:06PM +0200, Christoph Lameter wrote: > On Mon, 25 Apr 2022, Aaron Tomlin wrote: > > > Yes, in the context of nohz, this patch should ensure it, if required, when > > the idle tick is to be stopped. > > What I said was that it is generally useful. Even in the non NOHZ case. > > Folding the vmstat diffs *always* when entering idle prevents unnecessary > wakeups and processing in the future and also provides more accurate > counters for the VM allowing better decision to be made on reclaim. I'm thinking you're going to find a ton of regressions if you try it though; some workloads go idle *very* shortly, doing all this accounting is going to be counter-productive.