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

From: Michael Neuling <mikey@neuling•org>
To: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom•com>
Cc: Linux/PPC Development <linuxppc-dev@ozlabs•org>
Subject: Re: [PATCH] powerpc: Keep track of emulated instructions
Date: Tue, 07 Apr 2009 08:43:58 +1000	[thread overview]
Message-ID: <12794.1239057838@neuling.org> (raw)
In-Reply-To: <alpine.LRH.2.00.0904061430090.11076@vixen.sonytel.be>

In message <alpine.LRH.2.00.0904061430090.11076@vixen•sonytel.be> 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
> 
> Sony Techsoft Centre Europe
> The Corporate Village =B7 Da Vincilaan 7-D1 =B7 B-1935 Zaventem =B7 Belgium
> 
> Phone:    +32 (0)2 700 8453
> Fax:      +32 (0)2 700 8622
> E-mail:   Geert.Uytterhoeven@sonycom•com
> Internet: http://www.sony-europe.com/
> 
> A division of Sony Europe (Belgium) N.V.
> VAT BE 0413.825.160 =B7 RPR Brussels
> Fortis =B7 BIC GEBABEBB =B7 IBAN BE41293037680010
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@ozlabs•org
> https://ozlabs.org/mailman/listinfo/linuxppc-dev
> 