On Mon, 7 Jul 2008, Robert Watson wrote:
Since you're doing fine-grained performance measurements of a code path that
interests me a lot, could you compare the cost per-send on UDP for the
following four cases:
(1) sendto() to a specific address and port on a socket that has been bound
to
INADDR_ANY and a specific port.
(2) sendto() on a specific address and port on a socket that has been bound
to
a specific IP address (not INADDR_ANY) and a specific port.
(3) send() on a socket that has been connect()'d to a specific IP address and
a specific port, and bound to INADDR_ANY and a specific port.
(4) send() on a socket that has been connect()'d to a specific IP address
and a specific port, and bound to a specific IP address (not INADDR_ANY)
and a specific port.
The last of these should really be quite a bit faster than the first of
these, but I'd be interested in seeing specific measurements for each if
that's possible!
Not sure if I understand networking well enough to set these up quickly.
Does netrate use one of (3) or (4) now?
I can tell you vaguely about old results for netrate (send()) vs ttcp
(sendto()). send() is lighter weight of course, and this made a difference
of 10-20%, but after further tuning the difference became smaller, which
suggests that everything ends up waiting for something in common.
Now I can measure cache misses better and hope that a simple count of
cache misses will be a more reproducible indicator of significant
bottlenecks than pps. I got nowhere trying to reduce instruction
counts, possibly because it would take avoiding 100's of instructions
to get the same benefit as avoiding a single cache miss.
Bruce
_______________________________________________
freebsd-net@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "[EMAIL PROTECTED]"
