Date: Tue, 20 Sep 2005 12:41:50 -0600 (MDT) From: Vaibhave Agarwal <vaibhave@cs.utah.edu> To: rizzo@icir.org Cc: freebsd-net@freebsd.org Subject: options Hz=100000, scheduling at 10 microseconds Message-ID: <Pine.LNX.4.61.0509201239050.29644@trust.cs.utah.edu>
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hi, Just a little background - I want to fire events at 10 microsecond granularity in FreeBSD, and it was suggested to use Hz=100000 in the kernel config file. This is a good approach, only if I schedule events every 10 us ( which i am not doing ). Due to this high frequency interrupts, I am incurring a lot of overheads and deviations in firing events. I came across this other way of firing events at micro-seconds granularity, which uses "local APIC timer", by writing a us value into a register and generating the event when timer reaches zero. The implementation I know of is only in Linux. http://www.oberle.org/apic_timer.html and the technical paper is: http://stillhq.com/pdfdb/000522/data.pdf The paper shows that mean deviation of this approach is less than 3 us. But I can't find any such support for FreeBSD. Do you guys know of any such implementation for FreeBSD? Thanks for help, vaibhave
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