From mboxrd@z Thu Jan  1 00:00:00 1970
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [patch 8/9] Guest page hinting: discarded page list.
Date: Fri, 01 Sep 2006 17:40:19 +0200
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To: Dave Hansen <haveblue@us.ibm.com>
Cc: akpm@osdl.org, virtualization@lists.osdl.org, frankeh@watson.ibm.com, rhim@cc.gateh.edu, nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org
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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.