From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757204Ab0BKVtr (ORCPT ); Thu, 11 Feb 2010 16:49:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:1972 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757129Ab0BKVtp (ORCPT ); Thu, 11 Feb 2010 16:49:45 -0500 Message-ID: <4B747B6F.1090209@redhat.com> Date: Thu, 11 Feb 2010 16:49:35 -0500 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Lightning/1.0pre Thunderbird/3.0 MIME-Version: 1.0 To: Andrew Morton CC: "Luck, Tony" , Linux kernel Mailing List , shak Subject: Re: [PATCH -mm] change anon_vma linking to fix multi-process server scalability issue References: <20100128002000.2bf5e365@annuminas.surriel.com> <20100211130422.f262be71.akpm@linux-foundation.org> In-Reply-To: <20100211130422.f262be71.akpm@linux-foundation.org> 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 02/11/2010 04:04 PM, Andrew Morton wrote: > On Thu, 28 Jan 2010 00:20:00 -0500 > Rik van Riel wrote: > >> The old anon_vma code can lead to scalability issues with heavily >> forking workloads. Specifically, each anon_vma will be shared >> between the parent process and all its child processes. Some test results: Without the anon_vma changes, when AIM7 hits around 9.7k users (on a test box with 16GB RAM and not quite enough IO), the system ends up running >99% in system time, with every CPU on the same anon_vma lock in the pageout code. With these changes, AIM7 hits the cross-over point around 29.7k users. This happens with ~99% IO wait time, there never seems to be any spike in system time. The anon_vma lock contention appears to be resolved. -- All rights reversed.