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Cisco VPN Client freezes system with dual core CPU

 

It’s annoying as hell ! Not only we need to patch to use Cisco client on 64 bit systems, recently i find out Cisco don’t support SMP (multi core) in its VPN client. It means after you load the cisco module, there’s a big chance you will run into a kernel panic: oops, the whole desktop freezes and the only thing you can do is a hard restart. Nice.

There’s a way out of this: turn off SMP aka turn one core of your CPU off before the module is loaded:

  • sudo  echo 0 > /sys/devices/system/cpu/cpu1/online (to turn the 2nd core off, replace cpu1 with cpu2 for 3rd core and so on)
  • sudo  echo 1 > /sys/devices/system/cpu/cpu1/online (turn it back on)

But why the hell do we have to use one core only ?? I mean, if we buy multi core CPU, we want to use it ! It’s ok if you only use VPN occasionally, however for folks like me who is forced to use VPN all day then this is just plain dumb. Good work Cisco, i will stick with vpnc afterall, ktnxbye !

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  • http://www.lamnk.com Lamnk

    Very interesting ! Thanks a lot for mentioning this command. I haven't even heard about it before.

  • http://bohblog.blogspot.com/ Beau

    I've experiencing this freeze problem only when I use vpnclient over a wifi connection, not over a wired connection.

    I've been using this solution for a while, after finding it here. I mentioned my problems to a friend of mine and he suggested playing with processor affinity – assigning the vpnclient to a particular CPU.

    I've had a pretty good success this evening.

    Check out the command
    taskset

    and assign vpnclient to processor 0
    taskset -pc 0 vpnclient connect PCF_file

  • http://www.lamnk.com Lamnk

    Very interesting ! Thanks a lot for mentioning this command. I haven't even heard about it before.

  • http://computerkeepsfreezing.net/Products.html computer keeps freezing

    i haven't applied this line of command.i'm learning new things from you.thanks

  • Jack

    By far this article and the corresponding comments are the best info on this subject on the web. I've suffered with this issue for over a year – and still do unfort.

    I've tried EVERYTHING. Can't get OpenVPN or vpnc to work. I get a panic with cisco with wifi or ethernet on a duo core system (Lenovo T60) or on a single cpu Comcrap Presario.

    I have upgraded my kernel from 2.6.24.x to 2.6.31.x. Still no luck – though, interestingly enough Mandriva 2010 provides a cisco client with cpu1 shutdown commands built-in. Still doesn't help me though.

    I've tried shutting down cpu1 on my Lenovo and I still have the issue. I haven't tried loading cisco before the shutdown nor have I tried the cpu affinitytaskset trick. Sounds promising.

  • boynas

    You are the man! Beau… Thanks for that tip.

    so far so good!

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