From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754491AbbFPFnG (ORCPT ); Tue, 16 Jun 2015 01:43:06 -0400 Received: from lgeamrelo01.lge.com ([156.147.1.125]:41939 "EHLO lgeamrelo01.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751392AbbFPFm6 (ORCPT ); Tue, 16 Jun 2015 01:42:58 -0400 X-Original-SENDERIP: 10.177.222.220 X-Original-MAILFROM: iamjoonsoo.kim@lge.com Date: Tue, 16 Jun 2015 14:45:06 +0900 From: Joonsoo Kim To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Minchan Kim , Mel Gorman , Michal Nazarewicz , Naoya Horiguchi , Christoph Lameter , Rik van Riel , David Rientjes Subject: Re: [PATCH 5/6] mm, compaction: skip compound pages by order in free scanner Message-ID: <20150616054505.GE12641@js1304-P5Q-DELUXE> References: <1433928754-966-1-git-send-email-vbabka@suse.cz> <1433928754-966-6-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1433928754-966-6-git-send-email-vbabka@suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 10, 2015 at 11:32:33AM +0200, Vlastimil Babka wrote: > The compaction free scanner is looking for PageBuddy() pages and skipping all > others. For large compound pages such as THP or hugetlbfs, we can save a lot > of iterations if we skip them at once using their compound_order(). This is > generally unsafe and we can read a bogus value of order due to a race, but if > we are careful, the only danger is skipping too much. > > When tested with stress-highalloc from mmtests on 4GB system with 1GB hugetlbfs > pages, the vmstat compact_free_scanned count decreased by at least 15%. > > Signed-off-by: Vlastimil Babka Acked-by: Joonsoo Kim Thanks. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f182.google.com (mail-pd0-f182.google.com [209.85.192.182]) by kanga.kvack.org (Postfix) with ESMTP id 971536B006C for ; Tue, 16 Jun 2015 01:42:59 -0400 (EDT) Received: by pdjn11 with SMTP id n11so6495549pdj.0 for ; Mon, 15 Jun 2015 22:42:59 -0700 (PDT) Received: from lgeamrelo01.lge.com (lgeamrelo01.lge.com. [156.147.1.125]) by mx.google.com with ESMTP id f6si21112275pds.59.2015.06.15.22.42.57 for ; Mon, 15 Jun 2015 22:42:58 -0700 (PDT) Date: Tue, 16 Jun 2015 14:45:06 +0900 From: Joonsoo Kim Subject: Re: [PATCH 5/6] mm, compaction: skip compound pages by order in free scanner Message-ID: <20150616054505.GE12641@js1304-P5Q-DELUXE> References: <1433928754-966-1-git-send-email-vbabka@suse.cz> <1433928754-966-6-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1433928754-966-6-git-send-email-vbabka@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Minchan Kim , Mel Gorman , Michal Nazarewicz , Naoya Horiguchi , Christoph Lameter , Rik van Riel , David Rientjes On Wed, Jun 10, 2015 at 11:32:33AM +0200, Vlastimil Babka wrote: > The compaction free scanner is looking for PageBuddy() pages and skipping all > others. For large compound pages such as THP or hugetlbfs, we can save a lot > of iterations if we skip them at once using their compound_order(). This is > generally unsafe and we can read a bogus value of order due to a race, but if > we are careful, the only danger is skipping too much. > > When tested with stress-highalloc from mmtests on 4GB system with 1GB hugetlbfs > pages, the vmstat compact_free_scanned count decreased by at least 15%. > > Signed-off-by: Vlastimil Babka Acked-by: Joonsoo Kim Thanks. -- 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