From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754631Ab1G2Gxc (ORCPT ); Fri, 29 Jul 2011 02:53:32 -0400 Received: from out4.smtp.messagingengine.com ([66.111.4.28]:34806 "EHLO out4.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752574Ab1G2Gxa (ORCPT ); Fri, 29 Jul 2011 02:53:30 -0400 X-Sasl-enc: 4z5BELCxf7uF+GXIi9fNtEmEexZYnHAZNRiy9sXs7Foh 1311922409 Message-ID: <4E3258E1.6020000@fastmail.fm> Date: Fri, 29 Jul 2011 16:53:21 +1000 From: Greg Banks User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101208 Thunderbird/3.1.7 MIME-Version: 1.0 To: Eric Dumazet CC: NeilBrown , linux-nfs@vger.kernel.org, David Miller , linux-kernel , netdev Subject: Re: Fw: [PATCH] sunrpc: use better NUMA affinities References: <20110729153207.17af3085@notabene.brown> <4E324DB4.7060600@fastmail.fm> <1311921035.7845.10.camel@edumazet-laptop> In-Reply-To: <1311921035.7845.10.camel@edumazet-laptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/07/11 16:30, Eric Dumazet wrote: > Le vendredi 29 juillet 2011 à 16:05 +1000, Greg Banks a écrit : >> On 29/07/11 15:32, NeilBrown wrote: >> >> I seem to remember coming to the conclusion that Jeff eventually >> addressed this problem...am I misremembering or did something regress? >> > Currently, all nfsd kthreads use memory for their kernel stack and > various initial data from a _single_ node, even if you use > sunrpc.pool_mode=pernode (or percpu) That's just plain broken and I'm very pleased to see you fix it. I was just surprised that it was still broken and wondering how that happened. Looking at ToT I see that because I dropped the ball in 2008, Jeff's patches didn't address the problem. In ToT svc_pool_map_set_cpumask() is called *after* kthread_create() and applies to the child thread, *after* it's stack has been allocated on the wrong node. In the working SGI code, svc_pool_map_set_cpumask() is called by the parent node on itself *before* calling kernel_thread() or doing any of the data structure allocations, thus ensuring that everything gets allocated using the default memory allocation policy, which on SGI NFS servers was globally tuned to be "node-local". > With my patch, we make sure each thread gets its stack from its local > node. > > Check commit 94dcf29a11b3d20a (kthread: use kthread_create_on_node()) to > see how this strategy already was adopted for ksoftirqd, kworker, > migration, and pktgend kthreads. Ah, I see. It's unfortunate that the kthread_create() API ends up being passed a CPU number but that's only used to format the name and not for sensible things :( -- Greg.