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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,USER_AGENT_SANE_1 autolearn=ham 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 12804C47089 for ; Wed, 26 May 2021 17:41:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4A6D613CA for ; Wed, 26 May 2021 17:41:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234588AbhEZRmk (ORCPT ); Wed, 26 May 2021 13:42:40 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:51472 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229500AbhEZRmj (ORCPT ); Wed, 26 May 2021 13:42:39 -0400 Received: from imap.suse.de (imap-alt.suse-dmz.suse.de [192.168.254.47]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 268361FD29; Wed, 26 May 2021 17:41:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1622050866; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ANZCgAVJTkGUpqDp4fC/2nwLSoD1Lxi4nB0Czr/Ru98=; b=ybr8mpJOKZhb6clAQ14ucbgY85c1gAWEc0Pq4S+2fiAJJODhZNz/7sU/d/ChYsEqWSlHBO 7AysAhdNmR59awZvO86p/+tCRF8Ol3uEXNBV9aJQAX0mmnDeb4/uaVTd9+/ekLjqwrUbA6 +QUHIO1orMa0G/bghEsdx/JeEEsmGHE= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1622050866; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ANZCgAVJTkGUpqDp4fC/2nwLSoD1Lxi4nB0Czr/Ru98=; b=1tqNz5Z3UPqOu8ZjjVpqyE/vWfdNkTaZEUpa4Vf7PMz+euLh3BnHOqD0Yx+hGA6PYa3ggr lEEhXEvx6VOYiuDg== Received: from director2.suse.de (director2.suse-dmz.suse.de [192.168.254.72]) by imap.suse.de (Postfix) with ESMTPSA id 0FD9311A98; Wed, 26 May 2021 17:41:06 +0000 (UTC) Subject: Re: [PATCH 1/6] mm/page_alloc: Delete vm.percpu_pagelist_fraction To: Mel Gorman , Andrew Morton Cc: Hillf Danton , Dave Hansen , Michal Hocko , LKML , Linux-MM References: <20210525080119.5455-1-mgorman@techsingularity.net> <20210525080119.5455-2-mgorman@techsingularity.net> From: Vlastimil Babka Message-ID: <7b821c1f-ecc2-5e09-3c06-a63945d697ea@suse.cz> Date: Wed, 26 May 2021 19:41:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: <20210525080119.5455-2-mgorman@techsingularity.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/25/21 10:01 AM, Mel Gorman wrote: > The vm.percpu_pagelist_fraction is used to increase the batch and high > limits for the per-cpu page allocator (PCP). The intent behind the sysctl > is to reduce zone lock acquisition when allocating/freeing pages but it has > a problem. While it can decrease contention, it can also increase latency > on the allocation side due to unreasonably large batch sizes. This leads > to games where an administrator adjusts percpu_pagelist_fraction on the > fly to work around contention and allocation latency problems. > > This series aims to alleviate the problems with zone lock contention while > avoiding the allocation-side latency problems. For the purposes of review, > it's easier to remove this sysctl now and reintroduce a similar sysctl > later in the series that deals only with pcp->high. > > Signed-off-by: Mel Gorman > Acked-by: Dave Hansen Acked-by: Vlastimil Babka