On 2012-06-19 22:13, Alexander Neundorf wrote:
Considering a 8 or 16 core machine, this could give already 256 mocs
running on 16 cores. I think this would then really be a bit much.
I'd actually have to check first whether most of the time is spent in
executing moc, or in parsing the files for stuff to be moc'ed.
Also the parsing can still be optimized by caching results from earlier
runs (which it doesn't do right now).
For executing moc, this could also be limited to some number, like 2 or
4, which should already bring a lot.
Anyway, currently executing moc is very simple, it's a system-style
call, i.e. it starts the executable and blocks until the process has exited.
Making this non-blocking is a bit of work.
Right, as it turns out after I have automoc'ed all our projects I am
getting better parallelity. As you can see on this image I am getting
good value for my four cores and an incredibuild of our complete package
is down from about 12 minutes to 8 minutes and 30 seconds.
http://spear.medical-insight.com/~ts/automoc_build_time.png
So a big thanks to you and the CMake crew for giving us automoc support.
> automoc could start a background process and use that to handle all
> moc'ing. The process could stop after a few seconds of inactivity. That
> way moc would never use more than the number of cores in the machine,
> but it might overlap with other build activity. It doesn't seem sensible
> that automoc should only be concerned about overutilization from other
> mocs. Perhaps the best way is simply to look at the load-average, like
> make --load-average?
This must be cross-platform, i.e. work on Windows, OSX, Linux, *BSD,
AIX, etc.
This would be quite an effort I think.
I agree, before spending time on more parallelization it would be
interesting to take a look at moc itself. It appears to be significantly
slower on Windows than on Linux.
Thanks again,
Thomas
--
Powered by www.kitware.com
Visit other Kitware open-source projects at
http://www.kitware.com/opensource/opensource.html
Please keep messages on-topic and check the CMake FAQ at:
http://www.cmake.org/Wiki/CMake_FAQ
Follow this link to subscribe/unsubscribe:
http://public.kitware.com/cgi-bin/mailman/listinfo/cmake-developers
