Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751365Ab0LJGAH (ORCPT ); Fri, 10 Dec 2010 01:00:07 -0500 Received: from mail-ww0-f44.google.com ([74.125.82.44]:59821 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751143Ab0LJGAF (ORCPT ); Fri, 10 Dec 2010 01:00:05 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=BJ8LveQ46t++iG+au2cG62oganrdWFUsPtSJakRShEuYKvkjy8IUdWJkP/FZjwXuI4 dcXE+opxPjUpHzM6gjYrsdJGRR2xLnUajTm8/x0Bgf/+tKJZXA7g63brtet2KDGhBSO3 8MATXXZ+5EU+gzQ/yzvqf4FQy40JehHY2ihBA= Subject: Re: [PATCH v2 3/4] kthread: NUMA aware kthread_create_on_cpu() From: Eric Dumazet To: Andrew Morton Cc: Andi Kleen , linux-kernel , netdev , David Miller , Tejun Heo , Rusty Russell , Tony Luck , Fenghua Yu In-Reply-To: <20101209164438.fae1ba4c.akpm@linux-foundation.org> References: <1290972833.29196.90.camel@edumazet-laptop> <20101128224024.GA12300@basil.fritz.box> <1290984712.29196.100.camel@edumazet-laptop> <20101128230146.GB12300@basil.fritz.box> <1290987424.29196.128.camel@edumazet-laptop> <20101129090510.GA15763@basil.fritz.box> <1291023532.3435.29.camel@edumazet-laptop> <1291043695.3435.980.camel@edumazet-laptop> <20101209164438.fae1ba4c.akpm@linux-foundation.org> Content-Type: text/plain; charset="UTF-8" Date: Fri, 10 Dec 2010 06:59:58 +0100 Message-ID: <1291960798.2803.18.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2139 Lines: 58 Le jeudi 09 décembre 2010 à 16:44 -0800, Andrew Morton a écrit : > The name "kthread_create_on_cpu" is pretty misleading. > > One would expect such a function to create a kthread which is bound to > that CPU. But what it in fact does is to create a kthread which is > bound to all CPUs and whose stack, task_struct and thread_info were > allocated from the node which contains `cpu'. > > Also, a saner interface would be one which takes the numa_node_id, not > the cpu number. > > > > > ... > > > > /** > > - * kthread_create - create a kthread. > > + * kthread_create_on_cpu - create a kthread. > > * @threadfn: the function to run until signal_pending(current). > > * @data: data ptr for @threadfn. > > + * @cpu: cpu number. > > * @namefmt: printf-style name for the thread. > > * > > * Description: This helper function creates and names a kernel > > * thread. The thread will be stopped: use wake_up_process() to start > > * it. See also kthread_run(). > > * > > + * If thread is going to be bound on a particular cpu, give its number > > + * in @cpu, to get NUMA affinity for kthread stack, or else give -1. > > This is a bit presumptuous. The caller might wish to later bind this > thread to some or all of the CPUs on the node, rather than to a single > CPU (eg, kswapd()). > > > So what to do? Maybe add a new kthread_create_node() which prepares a > kthread whose memory is bound to that node, then add a > kthread_create_cpu() convenience wrapper around that? > We probably can add the "bind to cpu" as a fifth patch, to avoid one kthread_bind(p, cpu); done by these callers. My reasoning not including this kthread_bind(p, cpu) in initial patch series that I was focusing on NUMA properties first, not on scheduling (this part already runs correctly as far as I know) Thanks for taking the patch series, I was about to resubmit it today :) -- 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/