From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH v2.5 3/6] scsi_debug: add multiple queue support Date: Wed, 4 May 2016 15:32:40 -0700 Message-ID: <572A7888.6000804@sandisk.com> References: <1462070687-12689-1-git-send-email-dgilbert@interlog.com> <1462070687-12689-4-git-send-email-dgilbert@interlog.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-bn1bon0082.outbound.protection.outlook.com ([157.56.111.82]:26400 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752330AbcEDWcp (ORCPT ); Wed, 4 May 2016 18:32:45 -0400 In-Reply-To: <1462070687-12689-4-git-send-email-dgilbert@interlog.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Douglas Gilbert , linux-scsi@vger.kernel.org Cc: martin.petersen@oracle.com, tomas.winkler@intel.com, emilne@redhat.com, bart.vanassche@sandisk.com On 04/30/2016 07:44 PM, Douglas Gilbert wrote: > +static struct sdebug_queue *get_queue(void) > +{ > + struct sdebug_queue *sqp = sdebug_q_arr; > + > + return sqp + (raw_smp_processor_id() % submit_queues); > +} Does this function have the same purpose as blk_mq_map_queue()? If so, why has this function been introduced instead of using blk_mq_map_queue()? > @@ -5001,6 +5158,10 @@ static int scsi_debug_queuecommand(struct Scsi_Host *shost, > bool has_wlun_rl; > > scsi_set_resid(scp, 0); > + if (sdebug_statistics) { > + sqp = get_queue(); > + atomic_inc(&sqp->cmnd_count); > + } Why does scsi_debug_queuecommand() call get_queue() instead of blk_mq_unique_tag() and blk_mq_unique_tag_to_hwq() which is what other scsi-mq drivers do? Is the role of the sqp->cmnd_count counter identical to that of blk_mq_hw_ctx.queued? If so, can sqp->cmnd_count be left out and can blk_mq_hw_ctx.queued be used instead? > @@ -5168,6 +5328,16 @@ static int sdebug_driver_probe(struct device * dev) > + if (sdebug_mq_available && (submit_queues > 1)) > + hpnt->nr_hw_queues = submit_queues; There is already a submit_queues < 1 check in scsi_debug_init(). Is the submit_queues > 1 check in sdebug_driver_probe() needed? Bart.