From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752568AbcDZLUR (ORCPT ); Tue, 26 Apr 2016 07:20:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:59979 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752118AbcDZLUP (ORCPT ); Tue, 26 Apr 2016 07:20:15 -0400 Subject: Re: [PATCH 01/28] mm, page_alloc: Only check PageCompound for high-order pages To: Mel Gorman References: <1460710760-32601-1-git-send-email-mgorman@techsingularity.net> <1460710760-32601-2-git-send-email-mgorman@techsingularity.net> <571DE45B.2050504@suse.cz> <20160426103334.GB2858@techsingularity.net> Cc: Andrew Morton , Jesper Dangaard Brouer , Linux-MM , LKML From: Vlastimil Babka Message-ID: <571F4EED.2060208@suse.cz> Date: Tue, 26 Apr 2016 13:20:13 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.1 MIME-Version: 1.0 In-Reply-To: <20160426103334.GB2858@techsingularity.net> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/26/2016 12:33 PM, Mel Gorman wrote: > > I dithered on this a bit and could not convince myself that the order > case really is unlikely. It depends on the situation as we could be > tearing down a large THP-backed mapping. SLUB is also using compound > pages so it's both workload and configuration dependent whether this > path is really likely or not. Hmm I see. But e.g. buffered_rmqueue uses "if (likely(order == 0))" so it would be at least consistent. Also compound pages can amortize the extra cost over more base pages. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f72.google.com (mail-vk0-f72.google.com [209.85.213.72]) by kanga.kvack.org (Postfix) with ESMTP id C2D6E6B025E for ; Tue, 26 Apr 2016 07:20:15 -0400 (EDT) Received: by mail-vk0-f72.google.com with SMTP id n67so20118298vkf.1 for ; Tue, 26 Apr 2016 04:20:15 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id gi8si29437750wjc.158.2016.04.26.04.20.14 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 26 Apr 2016 04:20:14 -0700 (PDT) Subject: Re: [PATCH 01/28] mm, page_alloc: Only check PageCompound for high-order pages References: <1460710760-32601-1-git-send-email-mgorman@techsingularity.net> <1460710760-32601-2-git-send-email-mgorman@techsingularity.net> <571DE45B.2050504@suse.cz> <20160426103334.GB2858@techsingularity.net> From: Vlastimil Babka Message-ID: <571F4EED.2060208@suse.cz> Date: Tue, 26 Apr 2016 13:20:13 +0200 MIME-Version: 1.0 In-Reply-To: <20160426103334.GB2858@techsingularity.net> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Andrew Morton , Jesper Dangaard Brouer , Linux-MM , LKML On 04/26/2016 12:33 PM, Mel Gorman wrote: > > I dithered on this a bit and could not convince myself that the order > case really is unlikely. It depends on the situation as we could be > tearing down a large THP-backed mapping. SLUB is also using compound > pages so it's both workload and configuration dependent whether this > path is really likely or not. Hmm I see. But e.g. buffered_rmqueue uses "if (likely(order == 0))" so it would be at least consistent. Also compound pages can amortize the extra cost over more base pages. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org