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Date: Mon, 20 Jun 2005 19:57:27 -0700
From: eng@donut.ugcs.caltech.edu
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Subject: sustained sequential disk IO runs interactivity into the ground
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I was doing a dd of dev/zero into a file on a UFS2 filesystem
(softupdates disabled) on a clean 5.4-R system.

an exec of top took approximately 30 seconds to complete
and then revealed sys: 13% and idle: 87%

quit, repeat five times, same delay, same numbers each time.

FreeBSD 4.11 managed this with only a minor interactivity
hit.

What's going on here?  Any ideas?