From: "Steve Wise" <swise@opengridcomputing.com>
To: 'Ming Lin' <mlin@kernel.org>, 'Sagi Grimberg' <sagi@grimberg.me>,
linux-rdma@vger.kernel.org
Cc: 'Bart Van Assche' <bart.vanassche@sandisk.com>,
'target-devel' <target-devel@vger.kernel.org>
Subject: RE: iSER multi-queue configuration
Date: Mon, 2 May 2016 10:12:22 -0500 [thread overview]
Message-ID: <01c201d1a485$06cc8f50$1465adf0$@opengridcomputing.com> (raw)
In-Reply-To: <1462082826.11010.3.camel@kernel.org>
> -----Original Message-----
> From: linux-rdma-owner@vger.kernel.org [mailto:linux-rdma-
> owner@vger.kernel.org] On Behalf Of Ming Lin
> Sent: Sunday, May 01, 2016 1:07 AM
> To: Sagi Grimberg; linux-rdma@vger.kernel.org
> Cc: Bart Van Assche; target-devel
> Subject: Re: iSER multi-queue configuration
>
> On Sun, 2016-05-01 at 05:53 +0300, Sagi Grimberg wrote:
> > > Hi Sagi,
> >
> > Hi Ming,
> >
> > > I'm looking at why there is only 1 HW queue for iser.
> > >
> > > 2185 int scsi_mq_setup_tags(struct Scsi_Host *shost)
> > > 2186 {
> > > ...
> > > 2199 shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? :
> > > 1;
> > >
> > >
> > > It seems because iser code does not set shost->nr_hw_queues at all.
> > >
> > > Why?
> >
> > 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.
>
> >
> > 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.
> >
> > 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.
Ditto. SRP as a comparison is only useful for IB/RoCE transports. iSER will allow iWARP to play in the game as well...
Steve.
prev parent reply other threads:[~2016-05-02 15:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-29 21:11 iSER multi-queue configuration Ming Lin
2016-04-30 6:13 ` Ming Lin
[not found] ` <1461996836.4373.5.camel-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-05-01 2:53 ` Sagi Grimberg
[not found] ` <57256FB6.7030607-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
2016-05-01 6:07 ` Ming Lin
2016-05-02 15:12 ` Steve Wise [this message]
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