Invert sense of SLB class bit

[Sonny Rao]

On Thu, Sep 08, 2005 at 04:33:57PM +1000, Paul Mackerras wrote:
> Sonny Rao writes:
> 
> > So, when exactly do we go into real mode ?  I know the SLB handler is
> > now run in real mode, but is anything else? 
> 
> On every interrupt and exception (including system calls); i.e. every
> time we enter the kernel.  A few are handled entirely in real mode,
> but for most we do a small amount of exception entry code and then do
> an rfid instruction to turn the MMU back on.
> 
> > If we want to look at best-case improvements -- meaning a lot of SLB
> > reloading and userspace context-switching, I suppose I should select a
> > machine with a fair amount of memory.
> > 
> > Either way, I'm going to run SDET on a 2-way box w/ 8GB of RAM and see
> > if I can find a difference.  If necessary, I'll find a bigger box to
> > test on.
> 
> SDET sounds like a good choice, since it will do lots of system calls
> as well as context switches.
> 
> Is this a POWER5 machine?

Yes, actually a GS machine (SF2+).

Sonny