From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 662808D0047 for ; Thu, 10 Mar 2011 01:58:31 -0500 (EST) Received: by iwl42 with SMTP id 42so1723562iwl.14 for ; Wed, 09 Mar 2011 22:58:29 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20110309143704.194e8ee1.kamezawa.hiroyu@jp.fujitsu.com> References: <1299325456-2687-1-git-send-email-avagin@openvz.org> <20110305152056.GA1918@barrios-desktop> <4D72580D.4000208@gmail.com> <20110305155316.GB1918@barrios-desktop> <4D7267B6.6020406@gmail.com> <20110305170759.GC1918@barrios-desktop> <20110307135831.9e0d7eaa.akpm@linux-foundation.org> <20110309143704.194e8ee1.kamezawa.hiroyu@jp.fujitsu.com> Date: Thu, 10 Mar 2011 15:58:29 +0900 Message-ID: Subject: Re: [PATCH] mm: check zone->all_unreclaimable in all_unreclaimable() From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: Andrew Morton , Andrew Vagin , Andrey Vagin , Mel Gorman , KOSAKI Motohiro , linux-mm@kvack.org, linux-kernel@vger.kernel.org Hi Kame, Sorry for late response. I had a time to test this issue shortly because these day I am very busy. This issue was interesting to me. So I hope taking a time for enough testing when I have a time. I should find out root cause of livelock. I will answer your comment after it. :) Thanks! On Wed, Mar 9, 2011 at 2:37 PM, KAMEZAWA Hiroyuki wrote: > On Tue, 8 Mar 2011 08:45:51 +0900 > Minchan Kim wrote: > >> On Tue, Mar 8, 2011 at 6:58 AM, Andrew Morton wrote: >> > On Sun, 6 Mar 2011 02:07:59 +0900 >> > Minchan Kim wrote: >> > Any alternative proposals? =C2=A0We should get the livelock fixed if p= ossible.. >> > >> >> And we should avoid unnecessary OOM kill if possible. >> >> I think the problem is caused by (zone->pages_scanned < >> zone_reclaimable_pages(zone) * 6). I am not sure (* 6) is a best. It >> would be rather big on recent big DRAM machines. >> > > It means 3 times full-scan from the highest priority to the lowest > and cannot freed any pages. I think big memory machine tend to have > more cpus, so don't think it's big. > >> I think it is a trade-off between latency and OOM kill. >> If we decrease the magic value, maybe we should prevent the almost >> livelock but happens unnecessary OOM kill. >> > > Hmm, should I support a sacrifice feature 'some signal(SIGINT?) will be s= ent by > the kernel when it detects system memory is in short' in cgroup ? > (For example, if full LRU scan is done in a zone, notifier > =C2=A0works and SIGINT will be sent.) > >> And I think zone_reclaimable not fair. >> For example, too many scanning makes reclaimable state to >> unreclaimable state. Maybe it takes a very long time. But just some >> page free makes unreclaimable state to reclaimabe with very easy. So >> we need much painful reclaiming for changing reclaimable state with >> unreclaimabe state. it would affect latency very much. >> >> Maybe we need more smart zone_reclaimabe which is adaptive with memory p= ressure. >> > I agree. > > Thanks, > -Kame > > --=20 Kind regards, Minchan Kim -- 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