From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 1D15B6B0092 for ; Thu, 17 Dec 2009 09:45:21 -0500 (EST) Message-ID: <4B2A438A.6000908@redhat.com> Date: Thu, 17 Dec 2009 09:43:22 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: FWD: [PATCH v2] vmscan: limit concurrent reclaimers in shrink_zone References: <20091211164651.036f5340@annuminas.surriel.com> <1260810481.6666.13.camel@dhcp-100-19-198.bos.redhat.com> <20091217193818.9FA9.A69D9226@jp.fujitsu.com> <4B2A22C0.8080001@redhat.com> In-Reply-To: <4B2A22C0.8080001@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: lwoodman@redhat.com Cc: KOSAKI Motohiro , LKML , akpm@linux-foundation.org, linux-mm List-ID: On 12/17/2009 07:23 AM, Larry Woodman wrote: >>> The system would not respond so I dont know whats going on yet. I'll >>> add debug code to figure out why its in that state as soon as I get >>> access to the hardware. > > This was in response to Rik's first patch and seems to be fixed by the > latest path set. > > Finally, having said all that, the system still struggles reclaiming > memory with > ~10000 processes trying at the same time, you fix one bottleneck and it > moves > somewhere else. The latest run showed all but one running process > spinning in > page_lock_anon_vma() trying for the anon_vma_lock. I noticed that there are > ~5000 vma's linked to one anon_vma, this seems excessive!!! I have some ideas on how to keep processes waiting better on the per zone reclaim_wait waitqueue. For one, we should probably only do the lots-free wakeup if we have more than zone->pages_high free pages in the zone - having each of the waiters free some memory one after another should not be a problem as long as we do not have too much free memory in the zone. Currently it's a hair trigger, with the threshold for processes going into the page reclaim path and processes exiting it "plenty free" being exactly the same. Some hysteresis there could help. -- All rights reversed. -- 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/ . Don't email: email@kvack.org