Potential Speedup - gcc-3.2.x compiling large c++ projects

Greg Schafer gschafer at zip.com.au
Thu Feb 20 22:06:23 PST 2003

On Thu, Feb 20, 2003 at 07:16:03PM -0700, Gerard Beekmans wrote:
> On February 17, 2003 05:45 am, Greg Schafer wrote:
> > Apples and oranges.
> Okay I got myself two apples here.
> System is P4-2.2, 512 MB RAM
> gcc-3.2.1, binutils-2.13.1, no patch:
> 	qt-3.1.1 takes 58:26 minutes
> same config, but gcc-3.2.1+patch
> 	qt now takes 49:24 minutes.
> I quite like it.

Impressive. The gcc thread talked about "C++ templatized code" or something.
I don't grok c++ much so I don't really know which code is templatized and
which is not, but it seems like QT probably is.

I didn't expect to see much improvemnt in the bootstrapping of gcc itself.
It's marginally quicker, here are the numbers:-

gcc-3.2.2 (stock)                      gcc-3.2.2 (tweaked)

real    52m0.382s                      real    50m41.330s
user    49m29.860s                     user    47m54.040s
sys     2m15.160s                      sys     2m25.220s

And here are some glibc numbers:-

glibc-2.3.1                            glibc-2.3.1
(built with gcc-3.2.2 stock)           (built with gcc-3.2.2 tweaked)

real    35m30.937s                     real    35m12.586s
user    30m44.390s                     user    30m41.920s
sys     3m55.800s                      sys     3m56.840s

The good news is there are patches being developed to tweak this stuff
dynamically based on physical memory and other things and with a bit of luck
we might see it in gcc-3.3.

But for us still using gcc-3.2.x we are stuck with a "tweak by hand if you
have enough RAM" situation.

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