Subject: Re: [PATCH] powerpc: Keep track of emulated instructions

From: Michael Neuling <[email-masked]>
Date: Tue, 07 Apr 2009 08:43:58 +1000

In message <[email-masked]> you 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 k=
> eep
> > >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 tr=
> ack
> > >of
> > >the actual runtime overhead.
> > >
> > >Changes since last version:
> > > - arch/powerpc/kernel/sysfs.c is now compiled on ppc32, so we can provi=
> de
> > >   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.

Would per process counters be too hard?  Stick them in the thread_struct
and export them via /proc/<pid>/emulated. 

Mikey

> 
> > 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' fi=
> le?
> 
> BTW, should the individual counters be readable by everybody? Currently the=
> y're
> readable by root only.
> 
> With kind regards,
> 
> Geert Uytterhoeven
> Software Architect
> 
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