Re: TCP IP Offloading Interface

On 13 Jul 2003 09:22:32 -0700
Roland Dreier [off-list ref] wrote:

    David> TOE is evil, read this:

    David> http://www.usenix.org/events/hotos03/tech/full_papers/mogul/mogul.pdf

Your ideas are certainly very interesting, and I would be happy to see
hardware that supports flow identification.  But the Usenix paper
you're citing completely disagrees with you!

I didn't say I agree with all of Moguls ideas, just his anti-TOE
arguments.  For example, I also think RDMA sucks too yet he thinks
it's a good iea.

 For example, Mogul writes:

 "Nevertheless, copy-avoidance designs have not been widely adopted,
  due to significant limitations. For example, when network maximum
  segment size (MSS) values are smaller than VM page sizes, which is
  often the case, page-remapping techniques are insufficient (and
  page-remapping often imposes overheads of its own.)"

On send this doesn't matter, on receive you use my clever receive
buffer handling + flow cache idea to accumulate the data portion of
packets into page sized chunks for the networking to flip.

You obviously don't understand my ideas if you think that it matters
whether there is some relationship between the MTU and the system
page size necessary for the scheme to work.