Subject: Re: Linux support for RDMA (was: [Ksummit-2005-discuss] Summary of 2005 Kernel Summit Proposed Topics)

From: Ming Zhang <[email-masked]>
Date: Mon, 04 Apr 2005 08:58:20 -0400

On Mon, 2005-04-04 at 03:10, David S. Miller wrote:
> On Mon, 4 Apr 2005 00:34:56 -0600
> Grant Grundler <[email-masked]> wrote:
> 
> > Yes and No. PCI-X isn't fast enough but the data only crosses
> > the PCI-X bus once.  Think about the data flow:
> > 	1) DMA to RAM
> > 	2) load into CPU cache
> > 	3) store back into RAM
> > 
> > We are down to 40% left...graphics folks won't like you.
> 
> But you're missing the point, which is that the memory system
> always catches up to the networking technology.
> 
> We'll have that %60 back before you know it when we have
> PCI-Z and DDR8 or whatever even in $500.00USD desktop machines.
10G is supposed to be deployed in 2005 and 2006. while i did not see
DDR4 come out yet.

> 
> And those systems will be present by the time we put together
> this complicated infrastructure for RDMA.
> 
> RDMA is like cache coloring page allocators, it's for yesterday's
> technology that we won't be using tomorrow. :-)
> 
> Those steps #2 and #3 in your data flow are powerful, it is what
> gives us flexibility.  And in a general purpose OS that is important.