OSX network errors

OSX has a bug in its network stack, apparently associated with a 10.5 update, but it appears to fix slow performance on large file transfers on Tiger as well. Details are http://gp.darkproductions.com/2008/03/fix-for-slow-wifi-80211-file-transfers.html here. 

The main issue is the ack response, where both machines back of and wait for the other to ack, being far to polite. It appears to have fixed things for me backing up on a very very slow time capsule, which is not fast again.

The commands to reduce the ack are 

sysctl -w net.inet.tcp.delayed_ack=0

and to set it back to defailt 

sysctl -w net.inet.tcp.delayed_ack=3

and to list it

sysctl net.inet.tcp.delayed_ack

The annoying part is, if the a network mounted disk is mounted over a dodgy tcp connection, it will loose the mount and stall other disk activities. This can turn up as slow response, rather than total loss of the mount.

September 4, 2008 | Filed Under Thought

 

Comments

3 Responses to “OSX network errors”

  1. Ian Boston on September 10th, 2008 9:20 am

    And to make this permanent,
    echo net.inet.tcp.delayed_ack=0 >> /etc/sysctl.conf

  2. Misha on November 11th, 2008 12:48 pm

    I whant to set it permanently.
    After typing in terminal

    echo net.inet.tcp.delayed_ack=0 >> /etc/sysctl.conf

    or

    sudo echo net.inet.tcp.delayed_ack=0 >> /etc/sysctl.conf

    I’m getting ‘Permission denied’ error, what do I do wrong?

  3. Ian Boston on November 11th, 2008 2:44 pm

    /etc/sysctl.conf is probably not writable by you for some reason, try editing in vi

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