[distcc] [Fwd: "Busy" waiting when using distcc/ssh (and SMP question)]

[Martin Pool]

On  7 Jul 2003, Marcelo Matus <mmatus at dinha.acms.arizona.edu> wrote:

> Well, get more amazed, add the following lines to your .ssh/config file 
> (if you don't have them):
> 
> Host *
>     Compression yes
> 
> In my case, compiling  only against a remote host, the two cases gave me:
> 
> 1.-  export DISTCC_HOSTS="remotemachine"  ==> tcp/ip
> 
> real    1m48.889s
> user    0m6.380s
> sys     0m1.640s
> 
> 2.- export DISTCC_HOSTS="@remotemachine"  ==> ssh+compression
> 
> real    0m39.167s
> user    0m10.150s
> sys     0m1.700s

> Cool!, isn't?

It certainly is.

The upcoming 2.9 release with LZO compression should do at least as
well, and without the overhead of SSH for people with trusty networks.

Note that your case is slightly artificial because you're not building
anything much on localhost.  That means that compression of the source
file (the hardest part) is being done on a machine which is otherwise
nearly idle.  Of course, it's not completely unrealistic especially if
your local machine is really slow.  But a fairer comparison would be
-j4 with "localhost/2 @remotemachine/2".

> Note: I use make -j2, in both cases. I ran both cases with the
> distccmon-gnome and you can see that the "Sending file" with tcp/ip
> takes forever.
> 
> Maybe my files are too large (ugly C++ with a lot of includes and
> templates), and/or the network is too slow (direct 100Mb, using
> cross cable, no hub or switch), but here ssh is winning.

-- 
Martin