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

[Ming Zhang <mingz@xxxxxxxxxxx>]

yes, it travel 3 times instead of 1 time. and it is duplex. send traffic
will take another 20%. so total 80% or it can never run that fast.

ming

On Mon, 2005-04-04 at 02:34, Grant Grundler wrote:
> On Sun, Apr 03, 2005 at 05:56:11PM -0700, Dmitry Yusupov wrote:
> > I do not get your concern with memory BW. With good AMD box V40Z(SUN)
> > you can get 5.3GBytes/sec. Even with 10Gbps full speed you have 80%
> > left. PCI-X BUS BW is bigger concern...
> 
> 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.
> 
> grant