Re: [patch 3/9] Guest page hinting: volatile page cache.

Martin Schwidefsky
2006-09-01T15:31:22Z

On Fri, 2006-09-01 at 07:57 -0700, Dave Hansen wrote:
> > +#define PG_state_change 21 /* HV page state is changing. */
> > +#define PG_discarded 22 /* HV page has been discarded. */
>
> We're already desperately short on page flags on 32-bit architectures.
> It seems a wee bit silly to add two arch-generic flags for what is a
> very specialized arch-specific feature at this point.

There are even three additional page flags if you apply the full set of
patches.

> I know that there are 32-bit s390 kernels, but would this be a
> reasonable feature to restrict to only 64-bit kernels? That might be a
> decent compromise.

Yes, it is definitly an option to make this a 64-bit only features. In
particular because the ESSA instruction that is used on s390 is only
available in zarch mode (=64 bit).

--
blue skies,
Martin.

Martin Schwidefsky
Linux for zSeries Development & Services
IBM Deutschland Entwicklung GmbH

"Reality continues to ruin my life." - Calvin.