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Date: Sat, 31 Dec 2005 20:20:17 -0200
From: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
To: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>,
       Christoph Lameter <christoph@lameter.com>,
       Wu Fengguang <wfg@mail.ustc.edu.cn>, Nick Piggin <npiggin@suse.de>,
       Marijn Meijles <marijn@bitpit.net>
Subject: Re: [PATCH 1/9] clockpro-nonresident.patch
Message-ID: <20051231222017.GC4024@dmt.cnet>
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On Sat, Dec 31, 2005 at 09:53:11AM -0500, Rik van Riel wrote:
> On Sat, 31 Dec 2005, Peter Zijlstra wrote:
> 
> > > > +/*
> > > > + * For interactive workloads, we remember about as many non-resident pages
> > > > + * as we have actual memory pages.  For server workloads with large inter-
> > > > + * reference distances we could benefit from remembering more. 
> > > > + */
> > > 
> > > This comment is bogus. Interactive or server loads have nothing to do
> > > with the inter reference distance. To the contrary, interactive loads
> > > have a higher chance to contain large inter reference distances, and
> > > many common server loads have strong locality.
> > > 
> > > <snip>
> > 
> > Happy to drop it, Rik?
> 
> Sorry, but the comment is accurate.
> 
> For interactive workloads you want to forget interreference
> distances between two updatedbs, even if mozilla didn't get
> used all weekend.
> 
> OTOH, on NFS servers, or other systems with large interreference
> distances, you may _need_ to remember a larger set of non-resident
> pages in order to find the pages that are the hottest.
> 
> In those workloads, the shortest inter-reference distance might
> still be larger than the size of memory...

Sure, for the few cases you describe here the comment is valid.

Happy new year! 

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