From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladislav Bolkhovitin Subject: Re: [Scst-devel] Adjusting minimum packet size or "wait to merge requests" in SRP Date: Thu, 29 Oct 2009 21:30:41 +0300 Message-ID: <4AE9DF51.9020707@vlnb.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Chris Worley Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, scst-devel List-Id: linux-rdma@vger.kernel.org Chris Worley, on 10/28/2009 09:47 PM wrote: > It appears that SRP tries to coalesce and fragment initiator I/O > requests into 64KB packets, as that looks to be the size requested > to/from the device on the target side (and the I/O scheduler is > disabled on the target). > > Is there a way to control this, where no coalescing occurs when > latency is an issue and requests are small, and no fragmentation > occurs when requests are large? > > Or, am I totally wrong in my assumption that SRP is coalescing/fragmenting data? You can at any time see size of requests you are receiving on the target side by either enabling "scsi" logging (hopefully, you know how to do it) or by looking in /proc/scsi_tgt/sgv. In the latter file you will see general statistics for power of 2 allocations, i.e. request for 10K will increase 16K row. Vlad -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html