Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754912AbcKPBlU (ORCPT ); Tue, 15 Nov 2016 20:41:20 -0500 Received: from mail-qt0-f193.google.com ([209.85.216.193]:33721 "EHLO mail-qt0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751951AbcKPBlR (ORCPT ); Tue, 15 Nov 2016 20:41:17 -0500 MIME-Version: 1.0 In-Reply-To: <1478522920-108145-3-git-send-email-john.garry@huawei.com> References: <1478522920-108145-1-git-send-email-john.garry@huawei.com> <1478522920-108145-3-git-send-email-john.garry@huawei.com> From: Zhangfei Gao Date: Wed, 16 Nov 2016 09:41:16 +0800 Message-ID: Subject: Re: [PATCH 02/11] hisi_sas: alloc queue id of slot according to device id To: John Garry Cc: martin.petersen@oracle.com, jejb@linux.vnet.ibm.com, linux-scsi@vger.kernel.org, linuxarm@huawei.com, "linux-kernel@vger.kernel.org" , John Garry , Xiang Chen Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1086 Lines: 24 On Mon, Nov 7, 2016 at 8:48 PM, John Garry wrote: > From: Xiang Chen > > Currently slots are allocated from queues in a round-robin fashion. > This causes a problem for internal commands in device mode. For this > mode, we should ensure that the internal abort command is the last > command seen in the host for that device. We can only ensure this when > we place the internal abort command after the preceding commands for > device that in the same queue, as there is no order in which the host > will select a queue to execute the next command. Is there performance penalty, since only one queue is supported for a device. > > This queue restriction makes supporting scsi mq more tricky in > the future, but should not be a blocker. > > Note: Even though v1 hw does not support internal abort, the > allocation method is chosen to be the same for consistency. > > Signed-off-by: Xiang Chen > Signed-off-by: John Garry Reviewed-by: Zhangfei Gao