[PATCH] powerpc: Keep track of emulated instructions

[Geert Uytterhoeven]

On Mon, 6 Apr 2009, Geert Uytterhoeven wrote:
> On Fri, 3 Apr 2009, Kumar Gala wrote:
> > On Apr 3, 2009, at 7:08 AM, Geert Uytterhoeven wrote:
> > >Finally (after ca. 1.5 years), he're an updated version of my patch to keep
> > >track of emulated instructions.  In the light of Kumar's `Emulate enough of
> > >SPE
> > >instructions to make gcc happy' patch, he probably also wants to keep track
> > >of
> > >the actual runtime overhead.
> > >
> > >Changes since last version:
> > > - arch/powerpc/kernel/sysfs.c is now compiled on ppc32, so we can provide
> > >   counters in sysfs on ppc32, too,
> > > - WARN_EMULATED() is a no-op if CONFIG_SYSCTL is disabled,
> > > - Add warnings for altivec,
> > > - Add warnings for recently introduced emulation of vsx and isel
> > >   instructions.
> > 
> > pretty cool.  Do we think counters should be sysfs or debugfs?
> 
> What do you prefer?
> 
> On MIPS, unaligned exception handling control is in debugfs.

And probably debugfs is better, so it's disabled on production systems.
But I would drop the per-CPU counters, and keep global counters only, for
simplicity.

> > Also it would be nice to be able to zero out the counters.
> 
> By writing to the individual counters, or by writing to a global `clear' file?

With debugfs, it's quite easy to make them writable, so you can easily clear
them by writing zeroes to the virtual files.

If people agree, I'll find a time hole and start updating the code...

With kind regards,

Geert Uytterhoeven
Software Architect
Techsoft Centre

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