From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 9FE5F6B01C9 for ; Tue, 23 Mar 2010 14:33:54 -0400 (EDT) Date: Tue, 23 Mar 2010 13:31:43 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH 11/11] Do not compact within a preferred zone after a compaction failure In-Reply-To: <1269347146-7461-12-git-send-email-mel@csn.ul.ie> Message-ID: References: <1269347146-7461-1-git-send-email-mel@csn.ul.ie> <1269347146-7461-12-git-send-email-mel@csn.ul.ie> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: Andrew Morton , Andrea Arcangeli , Adam Litke , Avi Kivity , David Rientjes , Minchan Kim , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Tue, 23 Mar 2010, Mel Gorman wrote: > The fragmentation index may indicate that a failure it due to external s/it/is/ > fragmentation, a compaction run complete and an allocation failure still ??? > fail. There are two obvious reasons as to why > > o Page migration cannot move all pages so fragmentation remains > o A suitable page may exist but watermarks are not met > > In the event of compaction and allocation failure, this patch prevents > compaction happening for a short interval. It's only recorded on the compaction is "recorded"? deferred? > preferred zone but that should be enough coverage. This could have been > implemented similar to the zonelist_cache but the increased size of the > zonelist did not appear to be justified. > @@ -1787,6 +1787,9 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order, > */ > count_vm_event(COMPACTFAIL); > > + /* On failure, avoid compaction for a short time. */ > + defer_compaction(preferred_zone, jiffies + HZ/50); > + 20ms? How was that interval determined? -- 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