[distcc] very slow with many machines

[Daniel Kegel]

Stefan Heinrichsen wrote:
> I try to use distcc in a group of about 40 PCs. All PCs have a P4 2.6
> Ghz with 1GB Ram and are connected with 100MBit cards.
> I tried different values for -j.. from 70 to 150 but the compilie time
> always is the same. Without distcc it is about 10% _faster_.

We found that -j above 12 or so gave little improvement, so you probably
need to test with -j ranging from 1 to 20, not 70 to 150.

Note that the only way a cluster larger than N=12 or so is useful is
if multiple users (or build jobs) are sharing it, in which case
you might want to apply the 'randomize host' patch,
http://kegel.com/crosstool/crosstool-0.28-rc34/patches/distcc-2.16/randomhost.patch
and add the --randomize option at the top of the host list.
- Dan