cvs commit: src/sys/netinet/libalias alias_ftp.c alias_irc.c alias_local.h alias_proxy.c alias_skinny.c alias_smedia.c alias_util.c

[Alfred Perlstein]

Vendors don't sell performance, they sell features.

(you can quote me on that.)

* Luigi Rizzo <rizzo at icir.org> [050627 08:31] wrote:
> On Mon, Jun 27, 2005 at 06:21:55PM +0300, Ruslan Ermilov wrote:
> ...
> > Why can't we just say that checksum offloading is incompatible
> > with NAT (like with many other things), and do the software
> > checksum calculations in libalias?
> 
> actually the more i see it the more i think checksum offloading
> is a disgrace rather than a performance boost.
> 
> it needs a lot of special cases throughout the protocol stack
> to be supported properly, which constitutes extra overhead
> with low-end hardware which does not support the offloading;
> 
> it does not pay on small packets such as acks where you have
> to touch the whole packet anyways;
> 
> some hardware needs the checksum engine to be reprogrammed when
> changing protocol type (tcp <-> udp) which require extra I/O
> cycles on the bus that are expensive;
> 
> some hardware has broken checksum engines;
> 
> 	cheers
> 	luigi

-- 
- Alfred Perlstein
- email: bright at mu.org cell: 408-480-4684