odcm(4) - NetBSD Manual Pages

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ODCM(4)                 NetBSD Kernel Interfaces Manual                ODCM(4)


NAME

     odcm -- On-demand Clock Modulation


SYNOPSIS

     odcm0 at cpu0


DESCRIPTION

     The odcm driver provides support for changing the duty cycle of a CPU.
     This is sometimes known as ``on-demand clock modulation'' (ODCM).  Refer
     to acpicpu(4) for additional details about ODCM.

     The following sysctl(8) variables are available with odcm:

           machdep.clockmod.target      The target duty cycle of all CPUs.
                                        The values range from 7 (100 %) to 0
                                        (approximately 13 %).

           machdep.clockmod.current     The current duty cycle of CPUs.

           machdep.clockmod.available   A list of available duty cycles.

     Note that some errata may limit the availability of some duty cycles.


SEE ALSO

     acpicpu(4), est(4), powernow(4)


CAVEATS

     ODCM is meant for short-term thermal management, not power management.
     There is usually no reason for a system administrator to change the val-
     ues manually.  Lowering the duty cycle may dramatically decrease perfor-
     mance and responsiveness of the system.

NetBSD 6.0                       March 4, 2011                      NetBSD 6.0