Invert sense of SLB class bit

[Sonny Rao]

On Thu, Sep 08, 2005 at 02:32:04PM -0400, Sonny Rao wrote:
> On Thu, Sep 08, 2005 at 02:57:11AM -0400, Sonny Rao wrote:
> > 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.
> 
> Ok here are the results for 1,4,16, and 64 procs on stock 2.6.13 and
> 2.6.13 plus the patch.
> 
> the tests were run three times and averaged with the std. dev in parens
> 
> Kernel	1 proc		4 procs		16 procs	64 procs
> --	--		--		--		--
> stock	4580 (29)	14757 (215)	15246 (244)	15317 (52)
> patched	4556 (51)	14694 (116)	15320 (293)	15390 (38)
> 
> delta	-0.05 %		-0.04 %		+0.05 %		+0.05 %
> 
> In all cases except 64 procs, the std. deviation is bigger than the
> difference.  

Erk, I messed up, the percentages are off by a factor of ten,
it should be:

 delta	-0.5 %		-0.4 %		+0.5 %		+0.5 %

So, tenths of a percent rather than hundredths

Sonny