From: David Dillow <dave-i1Mk8JYDVaaSihdK6806/g@public.gmane.org>
To: Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Roland Dreier <rolandd-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>
Subject: Re: [PATCH 3/4 v3] IB/srp: adjust can_queue
Date: Tue, 03 Aug 2010 11:24:24 -0400 [thread overview]
Message-ID: <1280849064.20446.46.camel@lap75545.ornl.gov> (raw)
In-Reply-To: <201008031608.42244.bvanassche-HInyCGIudOg@public.gmane.org>
On Tue, 2010-08-03 at 16:08 +0200, Bart Van Assche wrote:
> The SRP (draft) standard specifies that an SRP initiator must never queue more
> than (SRP request limit) - 1 unanswered SRP_CMD information units. This patch
> makes sure that the SCSI mid-layer never tries to queue more than (SRP request
> limit) - 1 SCSI commands to ib_srp. This improves performance for targets
> whose request limit is less than or equal to SRP_SQ_REQ_SIZE (63) by reducing
> the number of BUSY responses reported by ib_srp to the SCSI mid-layer.
Actually, the standard states we can never send more than REQUEST LIMIT
requests. But we reserve 1 request for sending task management requests,
so that's why we need to tell the mid-layer to not send us more than
req_lim - 1 commands.
Dave
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next prev parent reply other threads:[~2010-08-03 15:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-03 14:08 [PATCH 3/4 v3] IB/srp: adjust can_queue Bart Van Assche
[not found] ` <201008031608.42244.bvanassche-HInyCGIudOg@public.gmane.org>
2010-08-03 15:24 ` David Dillow [this message]
[not found] ` <1280849064.20446.46.camel-FqX9LgGZnHWDB2HL1qBt2PIbXMQ5te18@public.gmane.org>
2010-08-04 16:44 ` Bart Van Assche
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