Re: Using -MMD instead of -MD for depndency generation

[Paul Smith]

On Wed, 2010-10-27 at 20:51 +0200, Ralf Wildenhues wrote:
> > I am talking about executing make after the source has been built once. E.g.
> > there is only one file changed and I want to rebuild the library with this
> > single new file. My benchmark is to type 'time make' on unchanged source. 
> > From
> > my expectation it will parse the GNUmakefile and all the files (the .Plo, Po
> > with the dependencies) included by it, then it needs to verify the
> > dependencies of all these rules for the 'all' target and then exits. Right 
> > now
> > this takes 5:42m usertime (+- 10 seconds).

I saw this come across my inbox and thought I'd give it a tree; 5:42
seems like a very, very long time.

I downloaded the tarball you linked to, to my system but wasn't able to
build; it configured and built about half the code, then failed:

          CXX    
WebKit/gtk/WebCoreSupport/libwebkitgtk_1_0_la-FullscreenVideoController.lo
        WebKit/gtk/WebCoreSupport/FullscreenVideoController.cpp:32: fatal 
error: gst/gst.h: No such file or directory

But I do have libgstreamer dev packages installed:

        webkit-1.3.5$ locate gst.h
        /usr/include/gstreamer-0.10/gst/gst.h
        

Do I need to do something else?


Anyway, with half the tree built (I think):

        webkit-1.3.5$ find -name \*.o | wc -l
        1437

make 3.81 takes about 8 seconds on my system to get back to trying to
build the above file, and failing.  I do notice that make 3.82 takes a
lot longer (23s !!) so there's definitely something I need to check out
in that respect.  But 5m seems pretty crazy.


FWIW, I have a Intel Core2 6600 at 2.4GHz with 2G RAM, running 64bit
2.6.35+ kernel on an ext4 partition.