From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753090AbbDCBPl (ORCPT ); Thu, 2 Apr 2015 21:15:41 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:36287 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752324AbbDCBPk (ORCPT ); Thu, 2 Apr 2015 21:15:40 -0400 Message-ID: <551DE9B4.2000403@kernel.dk> Date: Thu, 02 Apr 2015 19:15:32 -0600 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Rik van Riel , Frederic Weisbecker CC: axboe@kernel.org, fweisbec@redhat.com, mingo@kernel.org, linux-kernel@vger.kernel.org, lcapitulino@redhat.com, mtosatti@redhat.com Subject: Re: [PATCH RFC] nohz,blk-mq: do not create blk-mq workqueues on nohz dedicated CPUs References: <20150331102726.076a6860@annuminas.surriel.com> <551AB81F.8020806@kernel.dk> <20150331153310.GB29033@lerouge> <551AC093.6080500@kernel.dk> <551C18F4.2090407@redhat.com> In-Reply-To: <551C18F4.2090407@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/01/2015 10:12 AM, Rik van Riel wrote: > On 03/31/2015 11:43 AM, Jens Axboe wrote: > >> That'd be easy enough to do, that's how blk-mq handles offline CPUs as >> well. The attached patch is completely untested, but will handle offline >> or nohz CPUs in the same fashion - they will punt to hardware queue 0, >> which is mapped to CPU0 (and others, depending on the queue vs CPU ratio). > > I have done some sanity testing with your patch, > starting a KVM guest with vcpus and emulator threads > all pinned to nohz_full cpus. > > The guest is still able to do disk IO, so things > appear to work... > > Thanks for looking into this, Jens. > > Tested-by: Rik van Riel Great thanks, I'll do some sanity testing here too and get it applied for 4.1. -- Jens Axboe