On Fri, Sep 08, 2006 at 11:11:18PM +0200, Jose M. Prieto wrote: > TCP window scaling can be disabled by setting the kernel parameter > net.ipv4.tcp_window_scaling to 0 (I am sending this email from a 2.6.17, > after adding that setting to /etc/sysctl.conf). Disabling window scaling will > only slightly affect performance over high speed, long distance network > links, while having it enabled will greatly affect performance much more > often. So I think it would be wise to disable it in the default sysctl.conf. > If someone wants window scaling (s)he can comment out the line.
Allthough I'm not sure to really understand the problem, Mark Lord submited a
quick fix on the LKML [1] :
On Tue, Jun 13, 2006 at 12:58:05PM -0400, Mark Lord wrote:
> Okay. More progress here. The calculation of the "wscale" values is based on
> the "tcp_rmem" sysctl numbers.
>
> The defaults for these *differ* between 2.6.16.18 and 2.6.17-rc*.
>
> 2.6.16: 4096 87380 174760
> 2.6.17: 4096 87380 2097152
>
> If I change the tcp_rmem setting on 2.6.17 to match the old value, then the
> website www.everymac.com becomes accessible again:
>
> echo 4096 87380 174760 > /proc/sys/net/ipv4/tcp_rmem
As argued Linus Torvalds [2] and David Miller [3], disabling Window scaling is
a bad idea since according to David Miller " It is impossible to fill a
cross-continental connection without using window scaling. "
I would suggest people to use this trick instead of purely disabling Window
Scaling:
echo 4096 87380 174760 > /proc/sys/net/ipv4/tcp_rmem
At least, that's what I do since I got hit by this problem. It *does* work
fine.
My two cents.
[1] http://lkml.org/lkml/2006/6/13/144
[2] http://lkml.org/lkml/2006/6/13/159
[3] http://lkml.org/lkml/2006/6/13/217
--
Benoit Myard <[EMAIL PROTECTED]> [0x3EEC1AEC]
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