[CMake] Compilation speed with CMake/NMake combination, making it faster?

[Eric Noulard]

2007/12/11, Jason Stewart <jstewart at pobox.com>:
> This is not scientific but I wrote a quick perl script to compile a
> simple library that we use (GCTPc). It consists of 70 C files with most
> of the files between 5K and 6K, a few are as large as 70K. The script
> just uses the time() function to grab the elapsed seconds and runs three
> tests. The first runs one cl.exe process with all 70 files with the '-c'
> flag to only compile. The second compiles each C file with it's own
> invocation of cl.exe. The last repeats the first, but with the new,
> experimental, '/MP' flag that does multiprocessor builds.
>
> I get the following times for these files:
>     all files      : 2 seconds
>     single files : 7 seconds
>     mp build   : 1 second
>
> I repeated this test with a set of 15 C++ files that are larger with
> template code and that take significantly longer and I got the following
> times:
>     all files      : 60 seconds
>     single files : 78 seconds
>     mp build   : 51 seconds
>
> So, even on the single processor build the single invocation is almost
> 25% faster.
>
>
> Take it all with a grain of salt.

I'm not a big MS Platform user but I like the idea
of compilation speed-up very much.

I personnally use ccache (http://ccache.samba.org/)
on Linux + gcc and there is x2 up to x4 _SPEEDUP_
(when recompiling since initial compilation is slower)
on a C++ project with 50+ files with moderate template usage.

It seems that somebody did port ccache to work with MS CL:
http://artax.karlin.mff.cuni.cz/~kendy/blog/
http://artax.karlin.mff.cuni.cz/~kendy/ccache/

May be you can try it?



-- 
Erk