[parisc-linux] [patch 2/2] backport of sba sg list management to ccio-dma

[Grant Grundler]

On Thu, Nov 01, 2007 at 05:18:01PM +0000, Joel Soete wrote:
> here is short test:
> without udelay:
> # scp vmlinux  jso at patst007:/var/tmp/vmlinux-2.6.23-pa-d32up3

For testing NIC perf, please don't start with scp. Use ftp or something
else that doesn't use encryption. See www.netperf.org and/or iperf.

> Password:
> vmlinux                                                                     
>                100% 4364KB 101.5KB/s   00:43
>
> with udelay:
> # scp vmlinux  jso at patst007:/var/tmp/vmlinux-2.6.23-pa-d32up3
> Password:
> vmlinux                                                                     
>                100% 4364KB 436.4KB/s   00:10
>
> well still far from what we could expect (about 800KB/s) but fwiw something 
> supposing slowdown the kernel improve nic perf?

Yeah, that happens and it's clearly something wrong with the code.
Suggests there is contention either between CPU and IOTLB or between
CPU and IO device for a cacheline(s).

BTW, I'm assuming you have DELAYED_RESOURCE_CNT set to 16 or more.

thanks,
grant