Re: ISCSI: Urgent Flag requirement violates TCP.

[Matt Wakeley <matt_wakeley@agilent.com>]

Glen Turner wrote:

> Matt Wakeley wrote:
> >
> > > But when I look at the socket API for UNIX I can't see how
> > > a receiver can use Urgent data create a synchronisation point
> > > within a TCP stream.
> >
> > For a strictly software implementation, the urgent pointer provides no benefit at all.
> > This framing mechanism is to help special TCP/iSCSI accelerated implementations, not
> > iSCSI implemented using generic off the self TCP stacks.
> >
> > Sorry I forgot to mention that...
>
> Hi Matt,
>
> Actually, now I'm feeling even more confused.  I am assuming
> my cold is making me slow, so I apologise for that.
>
> Won't the client (the machine using the disk) almost always
> be a general purpose computer, and thus using an "off the shelf"
> TCP stack?

Nope.  Machines today using "off the shelf" stacks utilizing 1Gbps ethernet max out the CPU
running the TCP/IP stack, with no processing power left over for doing any work.  Machines
will not be able to fully utilize the new 10Gbps links if the TCP/IP processing is not
offloaded out of the main kernel.

-Matt Wakeley
Agilent Technologies