From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753304Ab1JLNOI (ORCPT ); Wed, 12 Oct 2011 09:14:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:61217 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753023Ab1JLNOF (ORCPT ); Wed, 12 Oct 2011 09:14:05 -0400 Message-ID: <4E959292.9060301@redhat.com> Date: Wed, 12 Oct 2011 09:13:54 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0.2) Gecko/20110906 Thunderbird/6.0.2 MIME-Version: 1.0 To: David Rientjes CC: Satoru Moriya , Randy Dunlap , Satoru Moriya , linux-kernel@vger.kernel.org, linux-mm@kvack.org, "lwoodman@redhat.com" , Seiji Aguchi , Andrew Morton , Hugh Dickins , "hannes@cmpxchg.org" Subject: Re: [PATCH -v2 -mm] add extra free kbytes tunable References: <20110901105208.3849a8ff@annuminas.surriel.com> <20110901100650.6d884589.rdunlap@xenotime.net> <20110901152650.7a63cb8b@annuminas.surriel.com> <65795E11DBF1E645A09CEC7EAEE94B9CB516CBBC@USINDEVS02.corp.hds.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/11/2011 05:04 PM, David Rientjes wrote: > In other words, I think it's a fine solution if you're running a single > application with very bursty memory allocations so you need to reclaim > more memory when low, but that solution is troublesome if it comes at > the penalty of other applications and that's a direct consequence of it > being a global tunable. I'd much rather identify memory allocations in > the kernel that causing the pain here and mitigate it by (i) attempting to > sanely rate limit those allocations, Rate limiting just increases the problem from what it was before the patch was introduced, because the entire purpose is to reduce allocation latencies by tasks with low latency requirements. > (ii) preallocate at least a partial > amount of those allocations ahead of time so avoid significant reclaim > all at one, Unless I'm mistaken, isn't this functionally equivalent to increasing the size of the free memory pool? > or (iii) annotate memory allocations with such potential so > that the page allocator can add this reclaim bonus itself only in these > conditions. I am not sure what you are proposing here. How would this scheme work? -- All rights reversed