Date: Wed, 14 Mar 2001 19:44:49 -0600 (CST) From: David Scheidt <dscheidt@tumbolia.com> To: Alfred Perlstein <bright@wintelcom.net> Cc: chat@freebsd.org Subject: Re: Disk I/O problem in 4.3-BETA Message-ID: <Pine.BSF.4.21.0103141941300.38966-100000@shell-2.enteract.com> In-Reply-To: <20010314154323.O29888@fw.wintelcom.net>
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On Wed, 14 Mar 2001, Alfred Perlstein wrote: :* Iain Templeton <iain@research.canon.com.au> [010314 14:54] wrote: :> On Mon, 12 Mar 2001, Alfred Perlstein wrote: :It's a common starvation problem. : :Imagine an elevator that always goes to the nearest requested floor :instead of making almost complete up then down sweeps. : :At quit time there's a good chance you'll never hit the lobby :because the elevator keeps going to the nearest floor which is :unlikely to be the lobby once it gets high up enough. : :Matt explained that Linux had this "feature" to reduce disk seeking :for a short period, finally someone with algorithm experience stood :up and smacked enough people around such that it got changed to :the proper elevator algorithm. HP introduced this problem (I think it was somewhat subtler than the way you've laid it out, though) into HP/UX 10.20 at some point. It meant that ls would take minutes(!!) to produce output on one of the boxes I ran, if it was being pounded on in a certain way. It's been fixed for a long time, though. Daivd -- dscheidt@tumbolia.com Bipedalism is only a fad. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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