Re: RDMAoE / lossless Ethernet (ewg: SC'09 BOF - Meeting notes)

[Roland Dreier <rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>]

 > Putting a side for a moment the detailed discussion we've started and
 > looking on the concluding remarks you have made, I wasn't sure to
 > follow:  if DCB isn't available (even from a silly reason of hw
 > supporting pfc but patches not being pushed to the kernel...) what you
 > think would function better (or function at all) for IBoE, lossy or
 > globally paused Ethernet? I haven't managed so far to convince you
 > that both aren't applicable for IBoE, but I also didn't manage to see
 > what are you suggesting in the absence of DCB.

I think you would have to enable pause to avoid dropping packets.  The
IB RC transport doesn't seem to be designed to recover from packet loss.

And my main point is that if you're only using a single VL, then there's
no real difference between DCB/PFC and classical ethernet flow control.
The fundamental difference with IB remains, namely credit-based
vs. pause-based flow control, so you'll need more buffering on ethernet.

 - R.
--
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