FIC M296 Manual Do Utilizador
Software Functional Overview
• If a standard single-speed fan is the Active cooling device, then the policy is
represented by the temperature to which _AC0 evaluates, and the fan is listed in
_AL0.
_AL0.
• If the zone uses two independently-controlled single-speed fans to regulate the
temperature, then _AC0 will evaluate to the maximum cooling temperature using two
fans, and _AC1 will evaluate to the standard cooling temperature using one fan.
fans, and _AC1 will evaluate to the standard cooling temperature using one fan.
• If a zone has a single fan with a low speed and a high speed, the _AC0 will evaluate
to the temperature associated with running the fan at high-speed, and _AC1 will
evaluate to the temperature associated with running the fan at low speed. _AL0 and
_AL1 will both point to different device objects associated with the same physical fan,
but control the fan at different speeds.
evaluate to the temperature associated with running the fan at low speed. _AL0 and
_AL1 will both point to different device objects associated with the same physical fan,
but control the fan at different speeds.
3.6.5 Passive Cooling Equation
Unlike the case for _ACx, during passive cooling the OS takes the initiative to actively
monitor the temperature in order to cool the platform. On an ACPI-compatible platform that
properly implements CPU throttling, the temperature transitions will be similar to the
following figure.
monitor the temperature in order to cool the platform. On an ACPI-compatible platform that
properly implements CPU throttling, the temperature transitions will be similar to the
following figure.
CPU Performance
Time
Temperature
100%
50%
ΔP
_TSP (Sampling period)
T
t
T
n - 1
T
n
For the OS to assess the optimum CPU performance change required to bring the temperature
down, the following equation must be incorporated into the OS.
down, the following equation must be incorporated into the OS.
ΔP [%] = _TC1 * ( Tn - Tn-1 ) + _TC2 * (Tn - Tt)
where
Tn = current temperature
Tt = target temperature (_PSV)
Tt = target temperature (_PSV)
The two coefficients _TC1 and _TC2 and the sampling period _TSP are hardware-dependent
constants the OEM must supply to the OS (for more information, see section 12.3). The
object _TSP contains a time interval that the OS uses to poll the hardware to sample the
temperature. Whenever _TSP time has elapsed, the OS will run _TMP to sample the current
temperature (shown as Tn in the above equation). Then the OS will use the sampled
temperature and _PSV (which is the target temperature Tt) to evaluate the equation for
ΔP.
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FIC M295 / M296 Service Manual