Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932071Ab1EXJQR (ORCPT ); Tue, 24 May 2011 05:16:17 -0400 Received: from cantor2.suse.de ([195.135.220.15]:41531 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755214Ab1EXJQO (ORCPT ); Tue, 24 May 2011 05:16:14 -0400 Date: Tue, 24 May 2011 10:16:11 +0100 From: Mel Gorman To: KOSAKI Motohiro Cc: minchan.kim@gmail.com, abarry@cray.com, akpm@linux-foundation.org, linux-mm@kvack.org, riel@redhat.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org Subject: Re: Unending loop in __alloc_pages_slowpath following OOM-kill; rfc: patch. Message-ID: <20110524091611.GD5279@suse.de> References: <4DCDA347.9080207@cray.com> <4DD2991B.5040707@cray.com> <20110520164924.GB2386@barrios-desktop> <4DDB3A1E.6090206@jp.fujitsu.com> <20110524083008.GA5279@suse.de> <4DDB6DF6.2050700@jp.fujitsu.com> <20110524084915.GC5279@suse.de> <4DDB74F7.9020109@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <4DDB74F7.9020109@jp.fujitsu.com> 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 Content-Length: 1078 Lines: 29 On Tue, May 24, 2011 at 06:05:59PM +0900, KOSAKI Motohiro wrote: > >>> Why? > >> > >> Otherwise, we don't have good PCP dropping trigger. Big machine might have > >> big pcp cache. > >> > > > > Big machines also have a large cost for sending IPIs. > > Yes. But it's only matter if IPIs are frequently happen. > But, drain_all_pages() is NOT only IPI source. some vmscan function (e.g. > try_to_umap) makes a lot of IPIs. > > Then, it's _relatively_ not costly. I have a question. Do you compare which > operation and drain_all_pages()? IOW, your "costly" mean which scenario suspect? > I am concerned that if the machine gets into trouble and we are failing to reclaim that sending more IPIs is not going to help any. There is no evidence at the moment that sending extra IPIs here will help anything. -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/