[Buildroot] [pull request] Pull request for branch for-2012.05/ccache-fixes
Thomas Petazzoni
thomas.petazzoni at free-electrons.com
Wed Mar 7 19:40:03 UTC 2012
Hello,
Le Wed, 7 Mar 2012 20:26:48 +0100,
Thomas Petazzoni <thomas.petazzoni at free-electrons.com> a écrit :
> ccache: set COMPILERCHECK to 'none'
Some numbers about this.
Without the patch, a build of Qt with an empty cache takes the
following time:
real 8m17.607s
user 31m30.830s
sys 1m8.990s
Without the patch, a build of Qt with a cache full takes the following
time:
real 8m12.630s
user 31m17.340s
sys 1m8.520s
So basically, no improvement.
With the patch, a build of Qt with a cache full takes the following
time:
real 4m37.559s
user 5m13.390s
sys 0m31.840s
Here, there is clearly a nice impact of ccache.
I have decided to take a simpler approach than the one explored by
Arnout. Arnout approach was, IMO, too complicated, and only applicable
to external toolchains.
My approach is simpler, but indeed requires attention from the
developer on whether the cache should be invalidated or not. However, I
am not sure it is possible to provide a solution that is both safe (in
terms of cache contents validity) *and* efficient (in terms of cache
usage). Also, the approach taken by my patch is basically the same as
what was happening with previous versions of ccache, so this is not a
new behaviour.
Best regards,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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