From mboxrd@z Thu Jan 1 00:00:00 1970 From: mina86@mina86.com (Michal Nazarewicz) Date: Mon, 12 Dec 2011 15:35:03 +0100 Subject: [PATCH 03/11] mm: mmzone: introduce zone_pfn_same_memmap() In-Reply-To: <20111212141953.GD3277@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> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org > 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. > That said, everywhere else managed to avoid checks like this by always > scanning in units of pageblocks. Maybe this should be structured > the same way to guarantee pfn_valid is called at least per pageblock > (even though only once per MAX_ORDER_NR_PAGES is necessary). I'll look into that. -- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Micha? ?mina86? Nazarewicz (o o) ooo +------------------ooO--(_)--Ooo--