Date: Mon, 4 Dec 2000 23:41:26 +0100 From: Bernd Walter <ticso@cicely5.cicely.de> To: janb@cs.utep.edu Cc: Bernd Walter <ticso@cicely8.cicely.de>, David Greenman <dg@root.com>, freebsd-current@FreeBSD.ORG Subject: Re: current paging strategy Message-ID: <20001204234126.A5927@cicely5.cicely.de> In-Reply-To: <Pine.GSO.4.30.0012041436290.19621-100000@gecko>; from janb@cs.utep.edu on Mon, Dec 04, 2000 at 02:36:44PM -0700 References: <20001105175745.A42346@cicely8.cicely.de> <Pine.GSO.4.30.0012041436290.19621-100000@gecko>
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On Mon, Dec 04, 2000 at 02:36:44PM -0700, janb@cs.utep.edu wrote: > what exacly do you mean with critical path, here? Performance critical. Most RISC platforms are optimized for 32 and maybe 64 bit structures. E.g. First generation alphas (without BWX) can't even access anything smaller than 32bit in memory without doing big magic. So one byte can become a big impact on performance. > On Sun, 5 Nov 2000, Bernd Walter wrote: > > On Thu, Nov 02, 2000 at 12:45:30AM -0800, David Greenman wrote: > > > >Interesting. THis needs about two bytes per page for the counter? > > > > > > Actually, we found that a single byte per page was sufficient. Pages tended > > > to be either heavily accessed or rarely accessed. Even in the unusual case > > > where all pages are frequently accessed, the page reclaim rate (and thus > > > adjustment rate of the page references count) increases high enough to still > > > provide for a decent distribution of the counters and for the page LOU to be > > > effective. > > > > One byte sounds good for i386. > > Maybe it makes sense to have it 4 or 8 byte on risc platforms. > > I wonder if it's a critical path and if there are more of this in > > the kernel source. -- B.Walter COSMO-Project http://www.cosmo-project.de ticso@cicely.de Usergroup info@cosmo-project.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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