82xx performance

[Arnd Bergmann]

On Thursday 17 July 2008, Rune Torgersen wrote:
> Arnd Bergmann wrote:
> > If you can't get it to work, readprofile(1) is a much simpler
> > tool, both in what it can do and what it requires you to do.
> 
> One thing that pops out is that handle_mm_fault uses twice as many
> ticks in arch/powerpc.

The other thing I found interesting is that cpu_idle is on the
top of the list in arch/powerpc but does not show up anywhere
in your top arch/ppc samples. This indicates that the system is
waiting for something, e.g. disk I/O for a significant amount
of time.

Seeing more hits in handle_mm_fault suggests that you have
a higher page fault rate. A trivial reason for this might
be that the amount of memory was misdetected in the new
code (maybe broken device tree). What is the content of
/proc/meminfo after a fresh boot?

If it's the same, try running a kernel build with 'time --verbose',
using GNU time instead of the bash builtin time to see how the
page fault rate changed.

	Arnd <><