[Libreoffice] gnumake / dependencies 20%+ speedup ...

[Bjoern Michaelsen]

On Fri, 02 Sep 2011 21:22:24 +0100
Michael Meeks <michael.meeks at novell.com> wrote:

> Hi there,
> 
> 	Being generally irritated by the apparent hang when running
> make (I know, I know it is all faster in real terms than it used to
> be ;-) I was poking at the dependency files in:
> 
> 	core/workdir/unxlngi6.pro/Dep/LinkTarget/Library
> 
> 	And - being of an ignorant nature, I was amazed to see them
> packed half-full of a great mass of dummy / empty dependency rules
> like these:
> 
> /data/opt/libreoffice/core/solver/unxlngi6.pro/inc/tools/string.hxx:
> 
> /data/opt/libreoffice/core/solver/unxlngi6.pro/inc/osl/thread.h:
> 
> ..
> 
> 	Using the attached perl script to remove these [ and I assume
> they are truly redundant ;-] we get some quite interesting shrinkage
> (gnumake profiles show most of its time parsing and hashing strings
> interestingly):
> 
> core/workdir/unxlngi6.pro/Dep/LinkTarget/Library> du -k -c *.d.orig |
> tail
> 12748 vbaobj.uno.so.d.orig
> 9720 vbaswobj.uno.so.d.orig
> 2096 vclcanvas.uno.so.d.orig
> 372 writerfilter_uno.uno.so.d.orig
> 603924 total
> 
> core/workdir/unxlngi6.pro/Dep/LinkTarget/Library> du -k -c *.d | tail
> 6424	vbaobj.uno.so.d
> 4904	vbaswobj.uno.so.d
> 1060	vclcanvas.uno.so.d
> 192	writerfilter_uno.uno.so.d
> 324084	total
> 
> 	ie. around 50% of the byte size is gone. That translates into:
> 
> * tail_build (clean make -sr / secs)
>     + before: 33.964 33.842 34.902
>     + after:  21.858 21.202 21.090
> * sc (clean make -sr / secs)
>     + before: 5.238 5.729 5.802
>     + after:  4.195 4.184 4.195
> 
> 	Of course when using cvs gnumake (which has the other
> globbing win in it - without which everything is far slower).
> 
> 	So - my question is: how are those library .d files created /
> concatenated - and is there some existing script we could piggy-back
> on to get rid of these.
> 
> 	Or are they there in fact there for some good purpose that I
> just failed to spot ? :-)

Yes, please read Caolans comments on:
https://bugs.freedesktop.org/show_bug.cgi?id=40099

Best,

Bjoern
-- 
https://launchpad.net/~bjoern-michaelsen