Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752076AbbEFR6t (ORCPT ); Wed, 6 May 2015 13:58:49 -0400 Received: from g4t3425.houston.hp.com ([15.201.208.53]:18319 "EHLO g4t3425.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751258AbbEFR6s (ORCPT ); Wed, 6 May 2015 13:58:48 -0400 Message-ID: <554A5655.6060108@hp.com> Date: Wed, 06 May 2015 13:58:45 -0400 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Mel Gorman CC: Andrew Morton , Nathan Zimmer , Dave Hansen , Scott Norton , Daniel J Blueman , Linux-MM , LKML Subject: Re: [PATCH 0/13] Parallel struct page initialisation v4 References: <1430231830-7702-1-git-send-email-mgorman@suse.de> <554030D1.8080509@hp.com> <5543F802.9090504@hp.com> <554415B1.2050702@hp.com> <20150504143046.9404c572486caf71bdef0676@linux-foundation.org> <20150505104514.GC2462@suse.de> <20150505130255.49ff76bbf0a3b32d884ab2ce@linux-foundation.org> <20150505221329.GE2462@suse.de> <20150505152549.037679566fad8c593df176ed@linux-foundation.org> <20150506071246.GF2462@suse.de> <20150506102220.GH2462@suse.de> In-Reply-To: <20150506102220.GH2462@suse.de> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2589 Lines: 55 On 05/06/2015 06:22 AM, Mel Gorman wrote: > On Wed, May 06, 2015 at 08:12:46AM +0100, Mel Gorman wrote: >> On Tue, May 05, 2015 at 03:25:49PM -0700, Andrew Morton wrote: >>> On Tue, 5 May 2015 23:13:29 +0100 Mel Gorman wrote: >>> >>>>> Alternatively, the page allocator can go off and synchronously >>>>> initialize some pageframes itself. Keep doing that until the >>>>> allocation attempt succeeds. >>>>> >>>> That was rejected during review of earlier attempts at this feature on >>>> the grounds that it impacted allocator fast paths. >>> eh? Changes are only needed on the allocation-attempt-failed path, >>> which is slow-path. >> We'd have to distinguish between falling back to other zones because the >> high zone is artifically exhausted and normal ALLOC_BATCH exhaustion. We'd >> also have to avoid falling back to remote nodes prematurely. While I have >> not tried an implementation, I expected they would need to be in the fast >> paths unless I used jump labels to get around it. I'm going to try altering >> when we initialise instead so that it happens earlier. >> > Which looks as follows. Waiman, a test on the 24TB machine would be > appreciated again. This patch should be applied instead of "mm: meminit: > Take into account that large system caches scale linearly with memory" > > ---8<--- > mm: meminit: Finish initialisation of memory before basic setup > > Waiman Long reported that 24TB machines hit OOM during basic setup when > struct page initialisation was deferred. One approach is to initialise memory > on demand but it interferes with page allocator paths. This patch creates > dedicated threads to initialise memory before basic setup. It then blocks > on a rw_semaphore until completion as a wait_queue and counter is overkill. > This may be slower to boot but it's simplier overall and also gets rid of a > lot of section mangling which existed so kswapd could do the initialisation. > > Signed-off-by: Mel Gorman > This patch moves the deferred meminit from kswapd to its own kernel threads started after smp_init(). However, the hash table allocation was done earlier than that. It seems like it will still run out of memory in the 24TB machine that I tested on. I will certainly try it out, but I doubt it will solve the problem on its own. Cheers, Longman -- 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/