[openib-general] How about ib_send_page() ?

[Michael Krause]

At 09:28 AM 6/7/2005, Fab Tillier wrote:
> > From: Roland Dreier [mailto:roland at topspin.com]
> > Sent: Tuesday, June 07, 2005 8:38 AM
> >
> >     Michael> Why not just use the IETF draft for RC / UC based IP over
> >     Michael> IB and not worry about creating something new?
> >
> > I think we've come full circle.  The original post was a suggestion on
> > how to handle the fact the the connected-mode IPoIB draft requires a
> > network stack to deal with different MTUs for different destinations
> > on the same logical link.
>
>That's right - by implementing IP segmentation in the IPoIB driver when going
>over UD, the driver could expose a single MTU to the network stack, thereby
>removing all the issues related to having per-endpoint MTUs.
>
>Keeping a 2K MTU for RC mode doesn't really take advantage of IB's RC
>capabilities.  I'd probably target 64K as the MTU.

The draft should state a minimum for all RC / UC which should be the TCP 
MSS.  Whether one does SAR over a UD endpoint independent of the underlying 
physical MTU can be done but it should not require end-to-end understanding 
of the operation, i.e. the send side tells its local that the TCP MSS is X 
while the receive side only posts 2-4 KB buffers.  This has been done over 
Ethernet for years.

Mike 
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