Re: [PATCH v2] tcp: splice as many packets as possible at once

Evgeniy Polyakov
2009-02-04T08:12:25Z

On Wed, Feb 04, 2009 at 07:19:47AM +0100, Willy Tarreau (w@1wt.eu) wrote:
> Yes myri10ge for the optimal 4080, but with e1000 too (though I don't
> remember the exact optimal value, I think it was slightly lower).

Very likely it is related to the allocator - the same allocation
overhead to get a page, but 2.5 times bigger frame.

> For the myri10ge, could this be caused by the cache footprint then ?
> I can also retry with various values between 4 and 9k, including
> values close to 8k. Maybe the fact that 4k is better than 9 is
> because we get better filling of all pages ?
>
> I also remember having used a 7 kB MTU on e1000 and dl2k in the past.
> BTW, 7k MTU on my NFS server which uses e1000 definitely stopped the
> allocation failures which were polluting the logs, so it's been running
> with that setting for years now.

Recent e1000 (e1000e) uses fragments, so it does not suffer from the
high-order allocation failures.

--
Evgeniy Polyakov