From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751336AbaGJGCC (ORCPT ); Thu, 10 Jul 2014 02:02:02 -0400 Received: from verein.lst.de ([213.95.11.211]:55599 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750725AbaGJGCA (ORCPT ); Thu, 10 Jul 2014 02:02:00 -0400 Date: Thu, 10 Jul 2014 08:01:55 +0200 From: Christoph Hellwig To: James Bottomley Cc: Christoph Hellwig , Jens Axboe , Bart Van Assche , Robert Elliott , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 08/14] scsi: convert device_busy to atomic_t Message-ID: <20140710060155.GA7675@lst.de> References: <1403715121-1201-1-git-send-email-hch@lst.de> <1403715121-1201-9-git-send-email-hch@lst.de> <1404924596.2006.6.camel@jarvis.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1404924596.2006.6.camel@jarvis.lan> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 09, 2014 at 09:49:56AM -0700, James Bottomley wrote: > As far as I can tell from the block MQ, we get one CPU thread per LUN. No, that's entirely incorrect. IFF a device supports multiple hardware queues we only submit I/O from CPUs (there might be more than one) this queue is bound to. With the single hardware queue supported by most hardware submissions can and will happen from any CPU. Note that this patchset doesn't even support multiple hardware queues yet, although it should be fairly simple to add once the low level driver support is ready.