[CMake] Do any CMake back ends have support for parallel builds that efficiently use clusters?

[Konstantin Tokarev]

12.01.2018, 12:58, "Alan W. Irwin" <irwin at beluga.phys.uvic.ca>:
> I am looking into the practicality of using clusters containing ~5
> cheap ARM 8-core computers (such as the Banana Pi M3) to rapidly build
> and test software (since even with ccache I am currently spending a
> lot of my time waiting for tests to complete as I develop my
> software). Such clusters would give you ~40 cores which is a lot of
> computer power for ~$500 or so. But, of course, the issue with
> clusters is how to use them efficiently?

1. For compilation you often need good single-core performance more
than parallelism, and I doubt that embedded-grade ARMv8 can provide it

I guess exception is compiling projects written in C which don't have huge
source files. Still, overhead of passing data between nodes may be
substanital.

2. You should probably use icecc or distcc, unless you have MPI as a
requirement.

>
> For one 8-core M3 you would expect
>
> make -j<NNN> target
>
> to scale linearly with NNN up to the saturation limit of roughly NNN=8
> (where target depends on ~hundreds of different and mostly independent
> tests). But my understanding from recent Google searching is that the
> -j option for GNU Make is not MPI-aware, i.e., only works for the
> cores for a single computer (node) in a cluster. So in a cluster you
> would have to assign the above task to just one node and simply accept
> that you cannot scale NNN up to the total number of cores in that
> cluster.
>
> I did find one reference to an effort (called the pmake project at
> Lawrence Livermore, see <https://computing.llnl.gov/code/pmake.html>)
> to modify GNU make to become MPI-aware so the above command would
> roughly scale NNN up to the number of cores in the cluster. But the
> single developer of the project seemed unable to overcome a bug in the
> result so that parallel make project was abandoned.
>
> I hope someone here can point me to a make variant (does Ninja
> qualify?) that does have the capability of scaling NNN up to the
> number of cores in the cluster since that would make clusters with a
> large number of cores become extremely useful for the purpose of quick
> testing by software developers.
>
> Alan
> __________________________
> Alan W. Irwin
>
> Astronomical research affiliation with Department of Physics and Astronomy,
> University of Victoria (astrowww.phys.uvic.ca).
>
> Programming affiliations with the FreeEOS equation-of-state
> implementation for stellar interiors (freeeos.sf.net); the Time
> Ephemerides project (timeephem.sf.net); PLplot scientific plotting
> software package (plplot.sf.net); the libLASi project
> (unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
> and the Linux Brochure Project (lbproject.sf.net).
> __________________________
>
> Linux-powered Science
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-- 
Regards,
Konstantin