Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755348AbcKPKDU (ORCPT ); Wed, 16 Nov 2016 05:03:20 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:37875 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752906AbcKPKDQ (ORCPT ); Wed, 16 Nov 2016 05:03:16 -0500 Subject: Re: [PATCH 02/11] hisi_sas: alloc queue id of slot according to device id To: Zhangfei Gao References: <1478522920-108145-1-git-send-email-john.garry@huawei.com> <1478522920-108145-3-git-send-email-john.garry@huawei.com> CC: , , , , "linux-kernel@vger.kernel.org" , John Garry , Xiang Chen From: John Garry Message-ID: Date: Wed, 16 Nov 2016 10:02:47 +0000 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.203.181.159] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1506 Lines: 42 On 16/11/2016 01:41, Zhangfei Gao wrote: > 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. Hi Zhangfei, From testing I have not seen any noteable performance change. However, please note the comment on mq, below. Cheers, John > >> >> 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 > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > . >