site_archiver@lists.apple.com Delivered-To: darwin-dev@lists.apple.com On Mar 8, 2008, at 4:22 PM, Andre-John Mas wrote: http://www.macosxhints.com/article.php?story=20080305053403936 Basically it suggests entering the following: sudo sysctl -w net.inet.tcp.delayed_ack=0 A responder to the MacOS X Hints article states: Greg Shenaut _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.appl... I recently came across this hint at MacOS X hints, suggesting a solution to speed up Airport transfer speeds:
From what I have been told this current setting is based on Nagle's algorithm, but reading up on it at Wikipedia I see: "This algorithm interacts badly with TCP delayed acknowledgments, a feature introduced into TCP at roughly the same time in the early 1980s, but by a different group. With both algorithms enabled, applications which do two successive writes to a TCP connection, followed by a read, experience a constant delay of up to 500 milliseconds, the "ACK delay". For this reason, TCP implementations usually provide applications with an interface to disable the Nagle algorithm. This is typically called the TCP_NODELAY option." "This bug has been documented for quite some time now, and NetBSD fixed". Is the current approach indeed outdated, needing borrowing changes from the NetBSD stack, or are there particular scenarios the NetBSD implementation handles badly?
I don't know if you've seen this: <http://www.stuartcheshire.org/papers/NagleDelayedAck/
but it's a very interesting read, and it explains exactly what is going on with the delay. This email sent to site_archiver@lists.apple.com