How do parallel builds scale?

[Ludovic Courtès]

Hello,

There was recently discussion as to how configure could be parallelized.

I ran a series of build time measurements on a 32-core machine, with
make -jX, with X in [1..32], and the results are available at:

  http://hubble.gforge.inria.fr/parallel-builds.html

There are also insightful per-package details:

  http://hubble.gforge.inria.fr/parallel-build-details.html

There are packages whose configuration phase is noticeably longer than
the build time.

OTOH, packages with a long build time (with a sequential time in
boldface) don’t scale well either, but that is not configure’s fault.

Thanks,
Ludo’.