On Fri, Aug 17, 2018 at 01:00:39AM +0100, Ken Moffat wrote:
> On Sun, Aug 12, 2018 at 11:15:06PM -0500, Brendan L wrote:
> > Not about llvm, but I agree about using cmake's ninja support. It
> > made building webkitgtk so much faster for me.
> >
>
> I meant to reply to this part of the thread:
>
> No problem for me with using ninja on cmake packages, but when I
> last looked at doing that (ages ago) it was because the inkscape
> devs were enthusing about it. And what I found was that on the
> packages I tried it had no benefit for a clean build - at that time
> the big benefits were for developers who changed something, did a
> build, changed something else and then needed to rebuild.
>
And I now agree that it IS faster. Dunno whether ninja has improved
or cmake's Makefiles have got worse, but building llvm with 4
available CPUs today (several times, the first time I thought I'd
mistyped something because it was so slow) I eventually discovered:
make -j4 : starts as 4 jobs (i.e. 400% CPU), but quickly falls back
to 1 job (100%) and later increases to 2 jobs (200%). Perhaps there
were brief other times when 4 jobs were running, but I had better
things to do than sit and continually look at 'top'.
ninja -j4 : consistently 400% CPU.
Similarly with running the tests, make builds as -j1 then runs tests
in parallel, ninja builds with multiple jobs.
ĸen
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