From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757573AbaLIQKP (ORCPT ); Tue, 9 Dec 2014 11:10:15 -0500 Received: from mail-pa0-f41.google.com ([209.85.220.41]:47646 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754480AbaLIQKN (ORCPT ); Tue, 9 Dec 2014 11:10:13 -0500 Message-ID: <54871EE2.3070502@kernel.dk> Date: Tue, 09 Dec 2014 09:10:10 -0700 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Bart Van Assche CC: Christoph Hellwig , Robert Elliott , Ming Lei , Alexander Gordeev , linux-kernel Subject: Re: [PATCH 4/6] blk-mq: Avoid that I/O hangs in bt_get() References: <54871BD0.8020305@acm.org> <54871C41.5040500@acm.org> In-Reply-To: <54871C41.5040500@acm.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 12/09/2014 08:58 AM, Bart Van Assche wrote: > Avoid that if there are fewer hardware queues than CPU threads that > bt_get() can hang. The symptoms of the hang were as follows: > * All tags allocated for a particular hardware queue. > * (nr_tags) pending commands for that hardware queue. > * No pending commands for the software queues associated with that > hardware queue. I already queued up the previous one, and added the extra tag get myself. -- Jens Axboe