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 X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC1DBC4BA24 for ; Thu, 27 Feb 2020 09:59:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91CE3222C2 for ; Thu, 27 Feb 2020 09:59:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582797544; bh=06Vr4fb9S78h9bNlh0lKeEo/QOWCjp42tLzTIj4gp6c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=g9gQyq6lYRFNYrX5F0b1mZFbTJH0XAMvanIStEwsVSENTTWUhQgDcim+rO5mM4i8a 3n705o1yuAFA503vN4i4Xc+9DXxqvE/+F3AhI/xVnNkqjcHAcCIaxa+hr+eKtrYDmY n9h49SFAqcSTNtA69TNxOtg2yxjP34XwP+rGyMR4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728687AbgB0J7D (ORCPT ); Thu, 27 Feb 2020 04:59:03 -0500 Received: from mail-wr1-f68.google.com ([209.85.221.68]:46207 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728627AbgB0J7D (ORCPT ); Thu, 27 Feb 2020 04:59:03 -0500 Received: by mail-wr1-f68.google.com with SMTP id j7so2451309wrp.13; Thu, 27 Feb 2020 01:59:01 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=VQ5cODCZxfkuaY7C2X27hLMvpBk5ErfD2dcMR1H0vUQ=; b=JJU0oNnazQsJt2bms+AMLR/OzVoAGmRebYNrmf2enIBVhIyVEh8UKPSPvU1QAB1yxw ISl9/mGH+qEazp4gKqF5/ZIsIvfbLfhqWyW9IzJZrliSNHkAv1WkrFSQVlArErG3ujm5 uSt0nk0gRc3EWkoWcy3un2IhRZAkCe3rLZKX6J3C8S/Y35XzHuTrfEj3dx3ZfrTx3idv dmKwIhW9+K3luWrlcViyVjptuR+jLjX2YMXxgrdCBf/odKqoA211p962V9/O0k6aXU2T KGT/0l/9B9x8Q2SIybxCyHmGV1+yt4/4pO4qtdM23qcbA/sJezmG+DowwYNdU/f0llPU /eTg== X-Gm-Message-State: APjAAAUvp7Ny8+kJ3XiSPxzoPWYMJDHeXcDiOrA+dRcU00q302rVCra7 wy1n0fgGGnMX3xiFGdNyfxE= X-Google-Smtp-Source: APXvYqyIHDqVdj4EvcgNGGEOqLGP0YnWFvgtDohXEArkdrFlu3228O8uGCdziWphEpOylyvx14xPRQ== X-Received: by 2002:adf:ed84:: with SMTP id c4mr3890509wro.24.1582797540999; Thu, 27 Feb 2020 01:59:00 -0800 (PST) Received: from localhost (prg-ext-pat.suse.com. [213.151.95.130]) by smtp.gmail.com with ESMTPSA id a198sm7226849wme.12.2020.02.27.01.58.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Feb 2020 01:58:59 -0800 (PST) Date: Thu, 27 Feb 2020 10:58:59 +0100 From: Michal Hocko To: Yang Shi Cc: Johannes Weiner , Shakeel Butt , Andrew Morton , Tejun Heo , Roman Gushchin , Linux MM , Cgroups , LKML , Kernel Team Subject: Re: [PATCH] mm: memcontrol: asynchronous reclaim for memory.high Message-ID: <20200227095859.GA3771@dhcp22.suse.cz> References: <20200219181219.54356-1-hannes@cmpxchg.org> <20200226222642.GB30206@cmpxchg.org> <2be6ac8d-e290-0a85-5cfa-084968a7fe36@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2be6ac8d-e290-0a85-5cfa-084968a7fe36@linux.alibaba.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 26-02-20 16:12:23, Yang Shi wrote: [...] > Actually I'm wondering if we really need account CPU cycles used by > background reclaimer or not. For our usecase (this may be not general), the > purpose of background reclaimer is to avoid latency sensitive workloads get > into direct relcaim (avoid the stall from direct relcaim). In fact it just > "steal" CPU cycles from lower priority or best-effort workloads to guarantee > latency sensitive workloads behave well. If the "stolen" CPU cycles are > accounted, it means the latency sensitive workloads would get throttled from > somewhere else later, i.e. by CPU share. I believe we need to because that work is not for free and so you are essentially stealing those CPUs cycles from everybody else outside of your throttled cgroup. -- Michal Hocko SUSE Labs