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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 6E751C4707A for ; Fri, 21 May 2021 22:57:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 46335613EE for ; Fri, 21 May 2021 22:57:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229967AbhEUW6v (ORCPT ); Fri, 21 May 2021 18:58:51 -0400 Received: from mga06.intel.com ([134.134.136.31]:62985 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229655AbhEUW6r (ORCPT ); Fri, 21 May 2021 18:58:47 -0400 IronPort-SDR: csUo8XrueBcM4iNAJ3ow1NNqW+phmr9SL1KLEfmuDD0Pe+h9qa1eu1VGAHxRZa+vjx/4//QLH9 0uTQxtgPgRvw== X-IronPort-AV: E=McAfee;i="6200,9189,9991"; a="262807288" X-IronPort-AV: E=Sophos;i="5.82,319,1613462400"; d="scan'208";a="262807288" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 May 2021 15:57:23 -0700 IronPort-SDR: xbpNSsUlAxTX/kbcdusQpqrnNZKQyJLWPlwqOf3U9AOiSy9mCymfZi6p5/rDxtZLfUdOL15TLe CDY1crP72yLA== X-IronPort-AV: E=Sophos;i="5.82,319,1613462400"; d="scan'208";a="441130087" Received: from djayapra-mobl2.amr.corp.intel.com (HELO [10.212.209.34]) ([10.212.209.34]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 May 2021 15:57:23 -0700 Subject: Re: [PATCH 6/6] mm/page_alloc: Introduce vm.percpu_pagelist_high_fraction To: Mel Gorman , Linux-MM Cc: Dave Hansen , Matthew Wilcox , Vlastimil Babka , Michal Hocko , Nicholas Piggin , LKML References: <20210521102826.28552-1-mgorman@techsingularity.net> <20210521102826.28552-7-mgorman@techsingularity.net> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210521102826.28552-7-mgorman@techsingularity.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/21/21 3:28 AM, Mel Gorman wrote: > This introduces a new sysctl vm.percpu_pagelist_high_fraction. It is > similar to the old vm.percpu_pagelist_fraction except it only adjusts > pcp->high to potentially reduce zone->lock contention while preserving > allocation latency when PCP lists have to be refilled. Look at me... Five patches later and I already forgot what the old one did and why it stinks. I wonder if you might do a wee bit of compare and contrast. Something like: The old vm.percpu_pagelist_fraction increased both the batch and high limits for the per-cpu page allocator. Its worst feature was that it led to absurdly large batch sizes that incurred nasty worst-case allocation latency. This new sysctl in comparison... Anyway, the approach looks sound to me. The batch size isn't important now, especially given the auto-scaling in patch 4. Acked-by: Dave Hansen