From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [RFC PATCH 0/2] block,scsi: support host-wide tagset Date: Tue, 4 Apr 2017 15:46:27 +0000 Message-ID: <1491320786.2513.7.camel@sandisk.com> References: <1491307665-47656-1-git-send-email-hare@suse.de> <20170404153234.GA3234@vader> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Received: from esa4.hgst.iphmx.com ([216.71.154.42]:19158 "EHLO esa4.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754863AbdDDPqa (ORCPT ); Tue, 4 Apr 2017 11:46:30 -0400 In-Reply-To: <20170404153234.GA3234@vader> Content-Language: en-US Content-ID: <38B818EFA0C34644A6A3DC0BA94F1E84@namprd04.prod.outlook.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "osandov@osandov.com" , "hare@suse.de" Cc: "hch@lst.de" , "james.bottomley@hansenpartnership.com" , "linux-scsi@vger.kernel.org" , "osandov@fb.com" , "linux-block@vger.kernel.org" , "martin.petersen@oracle.com" , "axboe@kernel.dk" On Tue, 2017-04-04 at 08:32 -0700, Omar Sandoval wrote: > blk-mq already supports a shared tagset, and scsi-mq already uses that. > When we initialize a request queue, we add it to a tagset with > blk_mq_add_queue_set(), where we automatically mark the tagset as shared > if there is more than one queue using it. What does this do that > BLK_MQ_F_TAG_SHARED doesn't cover? Hello Omar, Today blk-mq creates one tag set per hardware queue. The sharing by scsi-mq is between request queues for hardware queues that have the same index but not between hardware queues of a single request queue. My understanding is that the goal of this patch series is to make it possible to use a single tag set for all hardware queues and all request queues that share the same SCSI host. Bart.=