[distcc] homogeneous environments

[Martin Pool]

2009/4/29 Robert W. Anderson <anderson110 at poptop.llnl.gov>:
>
> I have an environment where we have many nodes potentially available for
> compilation, and all of them see the same file spaces via NFS.  We are
> seeing decent performance out of distcc 3.1 using pump mode, but from
> reading the docs there may be big performance gains left to wring out in
> this special(?) case.
>
> If I understand correctly, distcc's pump mode finds a set of header files
> necessary to send along with the source file to enable compilation on a
> remote node.  In a homogeneous environment, it seems both steps here are
> unnecessary if the master and slave nodes are more or less indistinguishable
> in terms of compiler, sources, and headers.

I'll just note that there are other existing tools built specifically
for the case of doing parallel builds across homogenous machines
sharing a single filesystem.  I think dmake and pmake may be able to
do this, and there are probably others, because it was a pretty common
configuration for unix machines some years ago.   It does have the
advantage you can potentially parallelize many different steps, not
just compilation.

However, as Fergus says, NFS is typically slower than streaming just
the files that are needed, so it's not a clear win.  You may also get
into trouble with different machines having slightly unsynchronized
views.

-- 
Martin <http://launchpad.net/~mbp/>