[Pkg-osg-devel] ccache

[Manuel A. Fernandez Montecelo]

Hi,

On Wednesday 26 January 2011 14:19:06 Alberto Luaces wrote:
> Hi,
> 
> while testing several changes that I'm commiting to the git repository,
> I noticed that 'ccache -s' reports always cache faults, even usually I
> don't make any changes to the source, issuing the compilation at normal
> (low) speed.
> 
> I think this comes from the fact that we are compiling OSG in two
> passes --- static and dynamic --- and as soon as ccache hits a file with
> the other configuration, it throws away the one that it had for the
> newer one. I thought it stored files by md5sum, not file name, that's
> why I'm surprised. Does it sound sensible?

Maybe when compiling different flags are issued, so the source file includes 
a slightly different content (e.g. "#define STATIC_BUILD 1"), and that 
causes the md5sum to be different?


> In that case maybe I could implement a switch system as it is done with
> patches, in order to at least reuse the last configuration:
> 
> static → dynamic → (recompilation) → dynamic → static →
> (recompilation)...
> 
> Or maybe is just fine for the testing period to comment out one of the
> configurations and uncomment it for commits :)

I usually compile in a big machine with 8 processors and use "parallel=10", 
so for me this is not a problem.

Maybe commenting out is enough, or some sort of switch can be implemented 
(if it's allowed by debian/rules guidelines): e.g. build optionally dynamic 
only:

http://www.debian.org/doc/debian-policy/ch-source.html#s-debianrules-options

Cheers.
-- 
Manuel A. Fernandez Montecelo <manuel.montezelo at gmail.com>