From mboxrd@z Thu Jan 1 00:00:00 1970 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 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta8.messagelabs.com (mail6.bemta8.messagelabs.com [216.82.243.55]) by kanga.kvack.org (Postfix) with ESMTP id 6C3936B0011 for ; Tue, 24 May 2011 05:16:15 -0400 (EDT) Date: Tue, 24 May 2011 10:16:11 +0100 From: Mel Gorman 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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, 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