Amos Shapira wrote:
> Someone at my workplace just implemented the top-part of the suggestions at
> this page: http://www-didc.lbl.gov/TCP-tuning/linux.html
> and got a 30x speedup (peaking at 50x speedup) on rsync of the mozilla mirror.

These sort of changes (increasing the tx/rx buffers of tcp) help when
your BDP (Bandwidth Delay Product) is larger than the maximum window.
Normally the window for Linux is 64K which is very small, but for a
normal 1.5Mbps DSL line it should be enough for full speed up to an RTT
of about 300ms, which covers any sane connection to the US (check the
results of ping <host> for RTT data).

One thing that might be is that he is using a relatively old version of
linux and there the auto adjust of the tcp memory didnt exist or didn't
function as well. Relatively new versions such as 2.6.13 and up will do
better.

> The page says it's good only for Gigbit connected hosts. What are the Israeli
> mirrors connected to?

Try to traceroute them to learn that.

> Are there other performance tunings on these mirrors?

If these servers didn't increase their own window size than the whole
exercise is pointless anyway, since the maximum window is limited by the
lowest buffer size.

Also, version of Linux before 2.6.15 had bugs in the BIC congestion
control algorithm, this may cause it to be too aggressive or not
aggressive enough, depending on the bug you hit. For most users it's not
that important, the data will get to them eventually. The congestion
control algorithm is effected by the sender side.

If you are mostly downloading you might want to set the congestion
control to Reno, this will lighten the load on your uplink side.

Baruch

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