Re: NetBSD 5.1 TCP performance issue (lots of ACK)

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Sat, Oct 22, 2011 at 03:21:34PM +0100, Matthias Scheler wrote:
> On Mon, Oct 17, 2011 at 06:03:18PM +0200, Manuel Bouyer wrote:
> > I've been playing with glusterfs a bit today, and found some performance
> > differences between NetBSD and linux, which I tracked down to our TCP
> > stack. Basically, between a NetBSD/linux pair, performances are much
> > better than between 2 NetBSD hosts.
> 
> What kind of network interfaces have these machines? And are you really
> using NetBSD 5.1 or NetBSD 5.1_STABLE? Have you enable hardware
> checksums under NetBSD? Linux turns them on by default.

Not sure this is really relevant -- Manuel has pointed out what seems
like it must be a serious issue with the TCP stack, namely its generation
of huge numbers of ACKs for data flows where the Linux stack ACKs about
as often as one would expect.

Thor