From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754380Ab3KTQUs (ORCPT ); Wed, 20 Nov 2013 11:20:48 -0500 Received: from merlin.infradead.org ([205.233.59.134]:45921 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754050Ab3KTQUo (ORCPT ); Wed, 20 Nov 2013 11:20:44 -0500 Message-ID: <528CE13D.3000907@kernel.dk> Date: Wed, 20 Nov 2013 09:20:13 -0700 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Christoph Hellwig CC: Dave Chinner , linux-kernel@vger.kernel.org Subject: Re: [Regression x2, 3.13-git] virtio block mq hang, iostat busted on virtio devices References: <20131119080218.GJ11434@dastard> <20131119201531.GA4094@kernel.dk> <20131119212042.GB4094@kernel.dk> <20131119213429.GQ11434@dastard> <528BDB97.8090608@kernel.dk> <20131120080440.GA13147@infradead.org> In-Reply-To: <20131120080440.GA13147@infradead.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/20/2013 01:04 AM, Christoph Hellwig wrote: > On Tue, Nov 19, 2013 at 02:43:51PM -0700, Jens Axboe wrote: >> No, the nr_requests isn't actually relevant in the blk-mq context, the >> driver sets its own depth. For the above, it's 64 normal commands, and 2 >> reserved. The reserved would be for a flush, for instance. If someone >> attempts to queue more than the allocated number of requests, it'll stop >> the blk-mq queue and kick things into gear on the virtio side. Then when >> requests complete, we start the queue again. > > Btw, any reason we lowerered the queue depth from 128 to 64 in > virtio-blk? No, we can easily bump it to 128 again, I think it was a leftover from where it had more queues and testing. -- Jens Axboe