UDP performance

[Serge Orlov]

Paul Sijben wrote:
> Serge Orlov wrote:
> > Paul Sijben wrote:
> >> I am stumped by the following problem. I have a large multi-threaded
> >> server accepting communications on one UDP port (chosen for its supposed
> >> speed).
> >>
> >> I have been profiling the code and found that the UDP communication is
> >> my biggest drain on performance! Communication where the client and the
> >> server are on the same machine still takes 300ms or sometimes much more
> >> per packet on an Athlon64 3000+ running Linux (Fedora Core 5 x64).
> >
> > [snip]
> >
> >> buf, address = socket.recvfrom(8192)
> >
> > I'm not an expert here, but I AFAIK UDP packet size should be kept
> > below 512 bytes otherwise it can cause fragmentation and hence all the
> > slow stuff like acknoledgements, timeouts, etc...
> >
> good point in general but in practice they are in this case. but this is
> less of a problem on the loopback interface anyway.

Isn't it still controlled by MTU even on the loopback? What is your MTU
on the loopback?