RE: VI (Was: Avoiding deadlock in iSCSI)

[Stephen Byan <Stephen.Byan@quantum.com>]

Matt Wakeley [mailto:matt_wakeley@agilent.com] wrote:

> I don't think VI/TCP helps at all.  The VI is implemented on 
> top of a TCP
> stream.  If the TCP stream delivers the iSCSI command to VI, 
> and VI has no
> place to put it, what is VI going to do?  It has to block the 
> TCP stream, and
> that in turn will block and "RDMA" from occurring.

If I understand correctly, VI/TCP has a credit-based flow control mechanism
on its message queues (which would be used to implement the iSCSI command
reception queue), and so the initiator would never send an iSCSI command
without a target buffer in which to store it. So RDMA cannot block on
commands in the TCP stream.

Regards,
-Steve

Steve Byan
<stephen.byan@quantum.com>
Design Engineer
MS 1-3/E23
333 South Street
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