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 60AA6C433EF for ; Thu, 24 Feb 2022 13:41:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235192AbiBXNll (ORCPT ); Thu, 24 Feb 2022 08:41:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235185AbiBXNlk (ORCPT ); Thu, 24 Feb 2022 08:41:40 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5590B4FC54 for ; Thu, 24 Feb 2022 05:41:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645710068; 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=weS+3HwpyorqpoTWq1H3W/L9srA7SlOeqlVBLs2cZd8=; b=EXHD0YLDqq9zTkBTWWwTgM4q3vzVgtElmlWLykMWT5ZKNFuLV7lc2rTmdAj3iR29BGCFwK Bp+OC404/hWQCggPra1p7XjI7twxsS79EvLwg5JHzHlhMLAYt1XdfcEho+WczQM56Aj620 TwPHkJ5HwPpdlyh17ctS7wCtgb3o18o= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-212-07YtHVyCNy2eWj5E8S71tQ-1; Thu, 24 Feb 2022 08:41:04 -0500 X-MC-Unique: 07YtHVyCNy2eWj5E8S71tQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 674251091DA2; Thu, 24 Feb 2022 13:41:03 +0000 (UTC) Received: from fuller.cnet (ovpn-112-2.gru2.redhat.com [10.97.112.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1347426DF6; Thu, 24 Feb 2022 13:41:03 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id 1723A416D862; Thu, 24 Feb 2022 10:40:42 -0300 (-03) Date: Thu, 24 Feb 2022 10:40:42 -0300 From: Marcelo Tosatti To: Aaron Tomlin Cc: Aaron Tomlin , Frederic Weisbecker , Christoph Lameter , tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Phil Auld Subject: Re: [RFC PATCH] tick/sched: Ensure quiet_vmstat() is called when the idle tick was stopped too Message-ID: References: <20220203214339.1889971-1-atomlin@redhat.com> <20220217124729.GA743618@lothringen> <20220217142615.xqtiydixvnumyvei@ava.usersys.com> <20220217163205.GA748087@lothringen> <20220218125454.utlgmuhijklzr3if@ava.usersys.com> <20220219154616.pwsvh445x3vn7ltf@ava.usersys.com> <20220224130014.rmhtx3xlepybuxn2@ava.usersys.com> <20220224132816.qsfa66ao3xdjdxxx@ava.usersys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220224132816.qsfa66ao3xdjdxxx@ava.usersys.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 24, 2022 at 01:28:16PM +0000, Aaron Tomlin wrote: > On Thu 2022-02-24 10:14 -0300, Marcelo Tosatti wrote: > > If the per-CPU vmstat_update is limited to happen once per second, that > > shouldnt be a significant performance impact? > > Perhaps not. Albeit, is the interrupt worth it? Its a requirement for correctness right? > Then again it could indeed > be a long time before the idle task is selected and a return to idle code > were we'd check for any remaining differentials with the aforementioned > patch. Or a long time before userspace returns to kernel.