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Date: Fri, 27 Jul 2001 21:14:59 -0500
From: Steven Walter <srwalter@yahoo.com>
To: Daniel Phillips <phillips@bonn-fries.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Addendum to Daniel Phillips [RFC] use-once patch
Message-ID: <20010727211459.A13603@hapablap.dyn.dhs.org>
In-Reply-To: <Pine.SV4.4.21.0107271524310.4696-100000@wipro.wipsys.sequent.com> <0107271638180F.00285@starship>
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In-Reply-To: <0107271638180F.00285@starship>; from phillips@bonn-fries.net on Fri, Jul 27, 2001 at 04:38:18PM +0200
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On Fri, Jul 27, 2001 at 04:38:18PM +0200, Daniel Phillips wrote:
> > may be
> > +                * it is the best candidate for swapping.
> > +                */
> > +               if ((page->age > PAGE_AGE_MAX) && (page_count(page)
> > <= 1)) {
> > +                       page->age = PAGE_AGE_START;
> > +               } else {
> > +                       page->age += PAGE_AGE_ADV;
> > +                       if (page->age > PAGE_AGE_MAX) {
> > +                               page->age = PAGE_AGE_MAX;
> > +                       }
> > +                       return;
> > +               }
> 
> I noticed your good benchmark results below, but I'm having some 
> trouble understanding how this works.  How can page->age ever become 
> greater than PAGE_AGE_MAX?  Also, I don't see any reference to 
> PAGE_MAX_USE.  Comments?

What if page->age is equal to PAGE_AGE_MAX when it hits the 'else'
statement.  It will be unconditionally incremented by PAGE_AGE_ADV, and
then it will be greater than PAGE_AGE_MAX.  The inner 'if' statement
catches this, and sets the age back to PAGE_AGE_MAX
-- 
-Steven
In a time of universal deceit, telling the truth is a revolutionary act.
			-- George Orwell
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