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From: Arnd Bergmann <arnd@arndb.de>
To: linuxppc-dev@ozlabs.org
Subject: Re: 82xx performance
Date: Thu, 17 Jul 2008 21:43:56 +0200
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On Thursday 17 July 2008, Rune Torgersen wrote:
> Arnd Bergmann wrote:
> > 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?
> Powerpc
> VmallocTotal:   474756 kB
> Ppc
> VmallocTotal:   245696 kB

This seems to be the only significant difference here, but
I don't see how it can make an impact on performance.

>         User time (seconds): 4339.11
>         User time (seconds): 4177.11

3.8% slowdown

>         System time (seconds): 319.41 
>         System time (seconds): 295.00

8.2% slowdown

>         Elapsed (wall clock) time (h:mm:ss or m:ss): 1:17:42
>         Elapsed (wall clock) time (h:mm:ss or m:ss): 1:14:35

4% slowdown

>         Minor (reclaiming a frame) page faults: 4213347
>         Minor (reclaiming a frame) page faults: 4203103

slightly more faults

>         Voluntary context switches: 53543
>         Voluntary context switches: 53812

This actually went down by 0.5%, both of these are well within
the expected 

>         Involuntary context switches: 90165
>         Involuntary context switches: 85856

4.8% more context switches, probably a side-effect of the longer
run-time.

So again, nothing conclusive. I'm running out of ideas.

	Arnd <><