Date: Thu, 7 Jul 2011 11:06:51 +0100 From: Steven Ayre <steveayre@gmail.com> To: freebsd-questions@freebsd.org Subject: kqueue + EVFILT_TIMER unreliable timing problems Message-ID: <CAFiqYu=MUo0LJn11Mrf9bueWwrmmzJL3wnndYw%2B5j6m3AWHDmw@mail.gmail.com>
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Hi everyone, I'm trying to use kqueue with EVFILT_TIMER to create an interval timer. However, I'm getting very unreliable results. The code for a test case is at: http://pastebin.com/ratK0AXL I'm finding that regardless of the number of ticks I wait for, it takes around 50% longer than it should. For a 20ms interval, 200 ticks takes 6s not 4s, 2000 takes 60s not 40s. I am running FreeBSD within a virtualbox VM (Windows host, no load) so I know timing may not be as reliable as if I was on the bare metal, but this still much higher than expected. -Steve
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