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=-5.8 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,URIBL_BLOCKED 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 58AB4C433E0 for ; Thu, 28 Jan 2021 22:16:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0CFA564DF8 for ; Thu, 28 Jan 2021 22:16:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231127AbhA1WQP (ORCPT ); Thu, 28 Jan 2021 17:16:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:40724 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229658AbhA1WQN (ORCPT ); Thu, 28 Jan 2021 17:16:13 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 71E5E60C41; Thu, 28 Jan 2021 22:15:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1611872133; bh=f+DCj2JfUNSoZg7jQcx8ZSeyCgEmsK+gf0UClqfV8/c=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=xqHNrx2L0rzVIHXj1eaVcjrpukXSsiToIagJcPFfsRuUKZPNr7blDMX1Tvra8b+aq zEJRuwIn+4iqZd6m/MrnjGDOUMkmR6IDt8JWov1EqHjTxf3hHtEcDqycOAfiJQWNmD s8eBer9fxaO1vX0esOiywcxH+E1Ir6yOnkVsBzVE= Date: Thu, 28 Jan 2021 14:15:31 -0800 From: Andrew Morton To: Mike Kravetz Cc: Oscar Salvador , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Naoya Horiguchi , Muchun Song , David Hildenbrand , Matthew Wilcox , Miaohe Lin Subject: Re: [PATCH v3 3/5] hugetlb: only set HPageMigratable for migratable hstates Message-Id: <20210128141531.17fec31e6075fe0eb6e33683@linux-foundation.org> In-Reply-To: <12187293-e972-acd8-7789-22ebfa736f95@oracle.com> References: <20210122195231.324857-1-mike.kravetz@oracle.com> <20210122195231.324857-4-mike.kravetz@oracle.com> <20210127103523.GI827@dhcp22.suse.cz> <2196d93e-f573-7163-183e-0ad2cec7555e@oracle.com> <20210128055221.GA3166@localhost.localdomain> <20210128133733.ce1fb2eac98ab5696c08f288@linux-foundation.org> <12187293-e972-acd8-7789-22ebfa736f95@oracle.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 28 Jan 2021 14:00:29 -0800 Mike Kravetz wrote: > On 1/28/21 1:37 PM, Andrew Morton wrote: > > On Thu, 28 Jan 2021 06:52:21 +0100 Oscar Salvador wrote: > > > >> On Wed, Jan 27, 2021 at 03:36:41PM -0800, Mike Kravetz wrote: > >>> Yes, this patch is somewhat optional. It should be a minor improvement > >>> in cases where we are dealing with hpages in a non-migratable hstate. > >>> Although, I do not believe this is the common case. > >>> > >>> The real reason for even looking into this was a comment by Oscar. With > >>> the name change to HPageMigratable, it implies that the page is migratable. > >>> However, this is not the case if the page's hstate does not support migration. > >>> So, if we check the hstate when setting the flag we can eliminate those > >>> cases where the page is certainly not migratable. > >>> > >>> I don't really love this patch. It has minimal functional value. > >>> > >>> Oscar, what do you think about dropping this? > >> > >> Yeah, I remember this topic arose during a discussion of patch#2 in the > >> early versions, about whether the renaming to HPageMigratable made > >> sense. > >> > >> Back then I thought that we could have this in one place at fault-path [1], > >> which should have made this prettier, but it is not the case. > >> True is that the optimization is little, so I am fine with dropping this > >> patch. > > > > I've dropped it. > > Thanks Andrew. > > Michal suggested that comments describing synchronization be added for each > flag. Since I did 'one patch per flag', that would be an update to each patch. > Or, I could simply add a patch to update the comment block based on what you > already have. > > Let me know what is best/easiest for you. I guess just one patch is best for reviewers. Then I'll split up into a sprinkle of -fix patches if I'm feeling energetic ;)