From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lin Subject: Re: iSER multi-queue configuration Date: Sat, 30 Apr 2016 23:07:06 -0700 Message-ID: <1462082826.11010.3.camel@kernel.org> References: <1461996836.4373.5.camel@kernel.org> <57256FB6.7030607@grimberg.me> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <57256FB6.7030607-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sagi Grimberg , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: Bart Van Assche , target-devel List-Id: linux-rdma@vger.kernel.org On Sun, 2016-05-01 at 05:53 +0300, Sagi Grimberg wrote: > > Hi Sagi, >=20 > Hi Ming, >=20 > > I'm looking at why there is only 1 HW queue for iser. > >=20 > > 2185 int scsi_mq_setup_tags(struct Scsi_Host *shost) > > 2186 { > > ... > > 2199=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0shost->ta= g_set.nr_hw_queues =3D shost->nr_hw_queues ? : > > 1; > >=20 > >=20 > > It seems because iser code does not set shost->nr_hw_queues at all. > >=20 > > Why? >=20 > The iscsi driver has not yet been converted to scsi_mq and iser as > an iscsi transport still does not use multi-queue. I'm going to compare performance between NVMe over RDMA and SCSI over RDMA. SRP supports scsi_mq, so I'd use SRP to do the apples-to-apples comparison. >=20 > In iscsi, a hw queue maps to an iscsi session. In order to support > multi-queue we need to have iscsi open multiple sessions and map > a session to a queue. >=20 > I had some preliminary works on this (joint with Mike Christie) but I > didn't have time thus far to implement a full conversion to scsi-mq. I'd happy to test it once you done. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html