Re: [patch 0/6] s390: qeth fixes for 2.6.30

David Miller
2009-03-25T23:47:04Z

From: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Date: Wed, 25 Mar 2009 09:25:14 +0100

> > Your EDDP was slow because the implementation was incredibly
> > sub-optimal. %90 of the code is doing copies and fiddling
> > with SKB internals.
>
> I did not wrote the EDDP code but this was my impression too. Thanks for
> confirming my study. Also the filling of the hardware buffers was not
> efficient and passing more buffers to the hw was expensive too.

I keep meaning to get back to a project I was working on that
would make generic the by-hand TSO that drivers such as
drivers/net/sfc/ are doing.

Just like this EDDP code seems to have been doing, they claim
to be TSO capable as a device but it is all done in software.

The hope is to write a generic framework, and skb_dma_map() and
skb_dma_unmap() were created as initial infrastructure for that.

Anyways, if I ever complete that project, drivers like qeth
could try to make use of it and do some perf tests.