A number of users have reported that transfers of large files on local are dramatically slower under Mac OS X 10.5.2. MacFixIt reader John Albergo remembered a fix that we noted in our Mac OS X 10.4.9 special report that involves modifying the delayed_ack parameter of Mac OS X’s TCP/IP configuration by entering the following command in the Terminal (located in Applications/Utilities):
- sudo sysctl -w net.inet.tcp.delayed_ack=0
then pressing return.
This workaround solved his slow throughput immediately.
“I recalled an issue from around the time of the Macbook Pro introduction, for which the workaround was to force the tcp parameter “delayed_ack” to zero. Suspecting a return or variant of that bug, I tried the workaround on both of my machines and the slowdown has not returned. I hesitate to declare a cure, but the throughput is rock solid so far, and at the speed I would normally expect. This implies that delayed ACKs are not being delivered in a timely manner.
“The blogger at this site wrote a small install script at the time to put an item in Startup Items to do the same thing each time you boot up — making it easily removed when no longer needed.”
Popularity: 4% [?]
Recent Comments