PERFORCE change 155748 for review

[Hans Petter Selasky]

On Thursday 08 January 2009, Ed Schouten wrote:
> * Hans Petter Selasky <hselasky at freebsd.org> wrote:
> > Everything is possible.
> >
> > How would you explain the benefit of the +19Mbyte of data resulting from
> > this autogeneration when building the modules ?
>
> I think we always had a preference to generate stuff on demand. It's a
> lot easier to maintain.

Hi,

I can understand that, but how about only generating the file once when you 
know it will be needed 60 times in a row? This also applies to other 
autogenerated files. It would speed up the module build alot I think.

cd src/sys/modules/usb2/serial_3g

make all clean

time make all
0:01.58

rm u3g2.o

time make all
0:00.96

You see it is around 50% slower to build a module which needs to generate N 
header files first, than if those header files were cached somewhere!

Multiply the time you save by 60, and we are talking about a significant 
amount of time!

--HPS