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=-12.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL 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 B78A4C43461 for ; Thu, 17 Sep 2020 18:31:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59DF5206CA for ; Thu, 17 Sep 2020 18:31:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="lkoFBIEW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726448AbgIQR2Y (ORCPT ); Thu, 17 Sep 2020 13:28:24 -0400 Received: from linux.microsoft.com ([13.77.154.182]:39160 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726559AbgIQR1k (ORCPT ); Thu, 17 Sep 2020 13:27:40 -0400 Received: from [192.168.0.121] (unknown [209.134.121.133]) by linux.microsoft.com (Postfix) with ESMTPSA id 85ED720B7178; Thu, 17 Sep 2020 10:27:17 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 85ED720B7178 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1600363638; bh=nNT59xiVCeQuSdxVsqpzlUhi5DP4GXX+M6O78MJ5HUY=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=lkoFBIEWN/+VNAKO+qdahC0B1JalSQTFsFRk3bY4tTWmN/9VxQKO7EwMKEz6prqEs eDXabN+nJtVpb+m05c0qIpvS+S+22q/E1TA0wOZjTg8fhZh15j92OTfWqAqCzcTaFD zDqnZGRWqhJF1xzocI27Rh59flOy0NrhQTinPTMw= Subject: Re: [v4] mm: khugepaged: avoid overriding min_free_kbytes set by user To: Michal Hocko Cc: Andrew Morton , "Kirill A. Shutemov" , Oleg Nesterov , Song Liu , Andrea Arcangeli , Pavel Tatashin , Allen Pais , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <1600324779-6782-1-git-send-email-vijayb@linux.microsoft.com> <20200917092805.GA29887@dhcp22.suse.cz> From: Vijay Balakrishna Message-ID: <21c4788c-2516-2e47-5885-486c352c2b6e@linux.microsoft.com> Date: Thu, 17 Sep 2020 10:27:16 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.2.2 MIME-Version: 1.0 In-Reply-To: <20200917092805.GA29887@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/17/2020 2:28 AM, Michal Hocko wrote: > On Wed 16-09-20 23:39:39, Vijay Balakrishna wrote: >> set_recommended_min_free_kbytes need to honor min_free_kbytes set by the >> user. Post start-of-day THP enable or memory hotplug operations can >> lose user specified min_free_kbytes, in particular when it is higher than >> calculated recommended value. > > I was about to recommend a more detailed explanation when I have > realized that this patch is not really needed after all. Unless I am > missing something. > > init_per_zone_wmark_min ignores the newly calculated min_free_kbytes if > it is lower than user_min_free_kbytes. So calculated min_free_kbytes >= > user_min_free_kbytes. > > Except for value clamping when the value is reduced and this likely > needs fixing. But set_recommended_min_free_kbytes should be fine. > IIUC, after start-of-day if a user performs - THP disable - modifies min_free_bytes - THP enable above sequence currently wouldn't result in calling init_per_zone_wmark_min. Thanks, Vijay