From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx127.postini.com [74.125.245.127]) by kanga.kvack.org (Postfix) with SMTP id A70106B017E for ; Mon, 12 Dec 2011 09:40:34 -0500 (EST) Date: Mon, 12 Dec 2011 14:40:30 +0000 From: Mel Gorman Subject: Re: [PATCH 03/11] mm: mmzone: introduce zone_pfn_same_memmap() Message-ID: <20111212144030.GF3277@csn.ul.ie> References: <1321634598-16859-1-git-send-email-m.szyprowski@samsung.com> <1321634598-16859-4-git-send-email-m.szyprowski@samsung.com> <20111212141953.GD3277@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Michal Nazarewicz Cc: Marek Szyprowski , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org, Kyungmin Park , Russell King , Andrew Morton , KAMEZAWA Hiroyuki , Ankita Garg , Daniel Walker , Arnd Bergmann , Jesse Barker , Jonathan Corbet , Shariq Hasnain , Chunsang Jeong , Dave Hansen On Mon, Dec 12, 2011 at 03:35:03PM +0100, Michal Nazarewicz wrote: > >On Fri, Nov 18, 2011 at 05:43:10PM +0100, Marek Szyprowski wrote: > >>From: Michal Nazarewicz > >>diff --git a/mm/compaction.c b/mm/compaction.c > >>index 6afae0e..09c9702 100644 > >>--- a/mm/compaction.c > >>+++ b/mm/compaction.c > >>@@ -111,7 +111,10 @@ skip: > >> > >> next: > >> pfn += isolated; > >>- page += isolated; > >>+ if (zone_pfn_same_memmap(pfn - isolated, pfn)) > >>+ page += isolated; > >>+ else > >>+ page = pfn_to_page(pfn); > >> } > > On Mon, 12 Dec 2011 15:19:53 +0100, Mel Gorman wrote: > >Is this necessary? > > > >We are isolating pages, the largest of which is a MAX_ORDER_NR_PAGES > >page. [...] > > This is not true for CMA. > To be clear, I'm referring to a single page being isolated here. It may or may not be a high-order page but it's still going to be less then MAX_ORDER_NR_PAGES so you should be able check when a new block is entered and pfn_to_page is necessary. -- Mel Gorman SUSE Labs -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org