[Libreoffice] ccache support

[Norbert Thiebaud]

On Fri, Sep 9, 2011 at 3:55 PM, Terrence Enger <tenger at iseries-guru.com> wrote:
> On Fri, 2011-09-09 at 14:22 -0500, Norbert Thiebaud wrote:
>>
>> Now granted, once we can reliably do incremental build, the question
>> of the effectiveness of ccache will be much more acute.
>> presumable incremental build only try to compile stuff that _need_ to
>> be compiled and therefore should be a ccache miss... so with perfect
>> incremental build the ccache hit should be 0%
>
> Not quite, I think.  Consider a header file changed within
> in #if-skipped region in a way which does not change the
> number of skipped lines.  I expect this would trigger a
> recompile and that ccache, other things being equal, would
> find a hit on the cache.  Does this sound plausible.
>
> Still, I would expect the hit rate to go really close to 0.

And as Lubos remarked earlier... you need to be in the 20% hit rate to
get your money-back...

Norbert