Re: rebuilding XFree86

["Mike A. Harris" <mharris www linux org uk>]

On Mon, 9 Feb 2004, Gene C. wrote:

>It has been a long, long time since I last rebuilt the XFree86 rpms ... at 
>that time it did not use buildroot.

Wow, that predates my existance at Red Hat.  ;o)

>So when I saw the need to rebuild the updates/testing version of XFree86 for 
>the x86_64,

You don't.  I have binary rpms I can make available if need be.  
They're always available for all architectures RHEL3 is available 
for.  Just might need to ask if they're not pushed to rawhide or 
on my ftp site.  I don't push them all unless someone wants them 
specifically, because my disk quota will overflow if I do it all 
the time.

>I was not looking forward to the amount of time it would take (I
>figured all afternoon).  Much to my surprise, it was done in
>less 90 minutes (how much less I do not know).

Takes 28 minutes to "rpmbuild --rebuild" the src.rpm on my 1.6Ghz 
Athlon 64 3000+, using ccache with a primed cache.  Double that 
for non-primed.

>Now I know that processors have gotten faster but the last time
>it seemed to take about 4 to 6 hours.

It took me 9 hours to compile XFree86 4.0.1 on my AMD K6 300Mhz, 
just over 3 years ago, with no special tricks such as 
compilercache of course.

>I do not know if it the faster processors (Opteron 140), code
>changes in XFree86, or local Red Hat stuff but this was a very
>pleasant surprise.

It's a combination of factors:

1) Much faster CPU and memory, and with larger CPU cache - that 
   makes a big difference for compilation.

2) The rpm uses parallelmake to an extent, it isn't perfect, but 
   it speeds up the build a fair bit nonetheless.

3) My fastbuild patch trims about 5-10% off build time

4) A few unnecessary things are disabled that aren't needed.

5) I've replaced ucs2any.pl with a version written in C.  It's 
   not a huge win, but it's a bit better.

There's no doubt some other important things I've forgotten 
about, but build speed is an amazingly important thing to me, and 
I try to keep it as low as possible.  Current XFree86 4.1.0 rpm 
builds take me 15 minutes at home, and that's on a dual Pentium 
III Xeon 1Ghz box, with 256Mb of RAM.  4.3.0 takes about 25 
minutes due to the makefiles not being as parallelized.

If you plan on building X more than once, *definitely* get ccache 
rpms off my ftp space on people.redhat.com.  It will cut XFree86 
build time in half on the second build.

If you've got 2 or more machines, check out distcc also, and 
parallelize the compilation across multiple machines on your 
network.  ;o)

Enjoy the speed.  ;o)


-- 
Mike A. Harris