DragonFly BSD
DragonFly kernel List (threaded) for 2009-10
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Re: kern.hz?

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Sun, 4 Oct 2009 09:32:54 -0700 (PDT)

    DragonFly doesn't use kern.hz for much beyond the callout timers and
    tsleep.  It uses independant systimers for scheduling and network
    polling.  FreeBSD upped their hz default primarily for their scheduler
    and network polling insofar as I remember.

    This is why DragonFly's hz was left at 100, and changing hz in DragonFly
    will not have much of an effect.

    Our scheduler clock is currently hardwired via ESTCPUFREQ in sys/proc.h
    We could make it programmable via sysctl... changing the frequency is
    really easy since it uses a systimer.  That would be a fun project for
    someone if they wanted to do it.  Calculations based on ESTCPUFREQ would
    have to be adjusted to be based on a variable instead.  ESTCPUFREQ
    is 50Hz at the moment.

    The networking polling frequency is set with a sysctl and only used
    if one or more interfaces has polling turned on.

					Matthew Dillon 

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