Re: [patch 8/9] Guest page hinting: discarded page list.

From: Martin Schwidefsky
Date: Fri Sep 01 2006 - 11:37:27 EST


On Fri, 2006-09-01 at 08:17 -0700, Dave Hansen wrote:
> > +#if defined(CONFIG_PAGE_DISCARD_LIST)
> > + if (page_host_discards() && unlikely(PageDiscarded(page))) {
> > + local_irq_disable();
> > + list_add_tail(&page->lru,
> > + &__get_cpu_var(page_discard_list));
> > + local_irq_enable();
> > + return;
> > + }
> > +#endif
>
> If PageDiscarded() was #ifdef'd in the header, you wouldn't need this in
> the .c file.

No, unfortunately not. There is a new variable page_discard_list that is
only defined if CONFG_PAGE_DISCARD_LIST is set. The compiler will
complain about the absence of the variable, even if the code is never
reached because PageDiscarded always returns 0.

--
blue skies,
Martin.

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

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


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