[PATCH] D23755: cmake: Add an ordering dep between HTML & man Sphinx targets

[Michał Górny via llvm-commits]

mgorny added a comment.

I've done two cold cache runs on my old dual-core Athlon64. The results (both runs were ~ the same):

serial:
real	1m32.180s
user	1m17.122s
sys	0m0.797s

parallel:
real	1m30.775s
user	2m0.950s
sys	0m0.898s

If I'm reading the results right, both variants give similar results, though the parallel run takes ~50% CPU time more (via not using cache from previous run).

Looking into what Sphinx does, the part of 'reading sources' (where cache is generated) takes the most time, writing HTML files is the second and writing manpages takes very little time. So while the most efficient solution would be to actually lock the doctree in Sphinx, therefore forcing its creation in serial and then create both file types in parallel, the manpage target takes so little time that it probably doesn't matter.


https://reviews.llvm.org/D23755