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 59B1A6B0011 for ; Tue, 24 May 2011 04:41:58 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp (unknown [10.0.50.74]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 7FB6C3EE0C2 for ; Tue, 24 May 2011 17:41:54 +0900 (JST) Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 651F545DECA for ; Tue, 24 May 2011 17:41:54 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 45DC145DE9C for ; Tue, 24 May 2011 17:41:54 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id C4A1FE78006 for ; Tue, 24 May 2011 17:41:53 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.240.81.145]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 8298F1DB803E for ; Tue, 24 May 2011 17:41:53 +0900 (JST) Message-ID: <4DDB6F48.1010809@jp.fujitsu.com> Date: Tue, 24 May 2011 17:41:44 +0900 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: Re: Unending loop in __alloc_pages_slowpath following OOM-kill; rfc: patch. References: <4DCDA347.9080207@cray.com> <4DD2991B.5040707@cray.com> <20110520164924.GB2386@barrios-desktop> <4DDB3A1E.6090206@jp.fujitsu.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: minchan.kim@gmail.com Cc: abarry@cray.com, akpm@linux-foundation.org, linux-mm@kvack.org, mgorman@suse.de, riel@redhat.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, fengguang.wu@intel.com >> I'm sorry I missed this thread long time. > > No problem. It would be better than not review. thx. >> In this case, I think we should call drain_all_pages(). then following >> patch is better. > > Strictly speaking, this problem isn't related to drain_all_pages. > This problem caused by lru empty but I admit it could work well if > your patch applied. > So yours could help, too. > >> However I also think your patch is valuable. because while the task is >> sleeping in wait_iff_congested(), an another task may free some pages. >> thus, rebalance path should try to get free pages. iow, you makes sense. > > Yes. > Off-topic. > I would like to move cond_resched below get_page_from_freelist in > __alloc_pages_direct_reclaim. Otherwise, it is likely we can be stolen > pages to other processes. > One more benefit is that if it's apparently OOM path(ie, > did_some_progress = 0), we can reduce OOM kill latency due to remove > unnecessary cond_resched. I agree. Can you please mind to send a patch? >> So, I'd like to propose to merge both your and my patch. > > Recently, there was discussion on drain_all_pages with Wu. > He saw much overhead in 8-core system, AFAIR. > I Cced Wu. > > How about checking per-cpu before calling drain_all_pages() than > unconditional calling? > if (per_cpu_ptr(zone->pageset, smp_processor_id()) > drain_all_pages(); > > Of course, It can miss other CPU free pages. But above routine assume > local cpu direct reclaim is successful but it failed by per-cpu. So I > think it works. Can you please tell me previous discussion url or mail subject? I mean, if it is costly and performance degression risk, we don't have to take my idea. Thanks. > > Thanks for good suggestion and Reviewed-by, KOSAKI. -- 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