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DragonFly users List (threaded) for 2010-06
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HEAD now has powerd for ACPI based cpu frequency adjustment.

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Mon, 28 Jun 2010 14:57:09 -0700 (PDT)

    HEAD now has a /usr/sbin/powerd daemon for systems which support
    ACPI based cpu frequency adjustment.  Your system supports this
    if it has the hw.acpi.cpu.px_dom* sysctls:

    sysctl hw.acpi | fgrep dom

    This is a first attempt from scratch daemon.  It takes no arguments
    and is very generous.  Any 1-second load > 0.25 will set the cpus
    to their maximum frequency.  When the 10-second load drops down
    below 0.12 the cpus will be set to their minimum frequency.

    The power savings is usually around 40%.  I'm not sure how well it
    works for a desktop/X environment as my current workstation has an
    old BIOS that doesn't support the feature, but it works very nicely
    on servers.

    If the 1-second delay to go to max-frequency isn't fast enough for
    a desktop environment we will probably need a kernel facility that
    the daemon can block on (so it doesn't have to poll quickly) and
    have the kernel wake it up when the instantanious load exceeds a
    certain value.  That way the daemon would be able to react within
    1/10 to 1/15 of a second or so.  Maybe the device event stuff being
    worked on can be used to support such a facility.

					Matthew Dillon 

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