> On Sun, Feb 10, 2008 at 01:39:09AM +0900, YAMAMOTO Takashi wrote:
> > > The decrement on exit would be cheaper than the loop around pmap_load.
> > > (I've just got a measurable performance gain from removing the loop.)
> >
> > what exactly do you mean by "removing the loop"?
>
> s/_RETRY//
does it imply that pmap_load is frequently called for your workload?
> Although I'd also put a 'cmp' and 'jz' after the call earlier, which
> is likely to be benefitialon athlons, but not P4 - which will predict
> the backwards jump as taken if the branch isn't in the branch cache.
do you mean the following?
1: ; \
cmpl $0, CPUVAR(WANT_PMAPLOAD) ; \
jz 1f ; \
call _C_LABEL(pmap_load) ; \
cmpl $0, CPUVAR(WANT_PMAPLOAD) ; \
jz 1f ; \
jmp 1b ; \
1:
YAMAMOTO Takashi
> My guess is that copyin will almost always have the pmap loaded,
> copyout probably more often than not.
>
>
> David
>
> --
> David Laight: david%l8s.co.uk@localhost