Intel E3815 FH8065301567411 Data Sheet
Product codes
FH8065301567411
Power Management
Intel
®
Atom™ Processor E3800 Product Family
Datasheet
89
•
Thermal Monitor mode.
— Refer to
6.3.2
Dynamic Cache Sizing
Dynamic Cache Sizing allows the processor to flush and disable a programmable
number of L2 cache ways upon each Deeper Sleep entry under the following condition:
number of L2 cache ways upon each Deeper Sleep entry under the following condition:
•
The C0 timer that tracks continuous residency in the Normal state, has not expired.
This timer is cleared during the first entry into Deeper Sleep to allow consecutive
Deeper Sleep entries to shrink the L2 cache as needed.
This timer is cleared during the first entry into Deeper Sleep to allow consecutive
Deeper Sleep entries to shrink the L2 cache as needed.
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The predefined L2 shrink threshold is triggered.
The number of L2 cache ways disabled upon each Deeper Sleep entry is configured in
the BBL_CR_CTL3 MSR. The C0 timer is referenced through the
CLOCK_CORE_CST_CONTROL_STT MSR. The shrink threshold under which the L2
cache size is reduced is configured in the PMG_CST_CONFIG_CONTROL MSR. If the
ratio is zero, then the ratio will not be taken into account for Dynamic Cache Sizing
decisions. Refer to the BIOS Writer’s Guide for more details.
the BBL_CR_CTL3 MSR. The C0 timer is referenced through the
CLOCK_CORE_CST_CONTROL_STT MSR. The shrink threshold under which the L2
cache size is reduced is configured in the PMG_CST_CONFIG_CONTROL MSR. If the
ratio is zero, then the ratio will not be taken into account for Dynamic Cache Sizing
decisions. Refer to the BIOS Writer’s Guide for more details.
6.3.3
Low-Power Idle States
When the processor core is idle, low-power idle states (C-states) are used to save
power. More power savings actions are taken for numerically higher C-state. However,
higher C-states have longer exit and entry latencies. Resolution of C-state occur at the
thread, processor core, and processor core level.
power. More power savings actions are taken for numerically higher C-state. However,
higher C-states have longer exit and entry latencies. Resolution of C-state occur at the
thread, processor core, and processor core level.
6.3.3.1
Clock Control and Low-Power States
The processor core supports low power states at core level. The central power
management logic ensures the entire processor core enters the new common processor
core power state. For processor core power states higher than C1, this would be done
by initiating a P_LVLx (P_LVL6) I/O read to all of the cores. States that require external
intervention and typically map back to processor core power states. States for
processor core include Normal (C0, C1).
management logic ensures the entire processor core enters the new common processor
core power state. For processor core power states higher than C1, this would be done
by initiating a P_LVLx (P_LVL6) I/O read to all of the cores. States that require external
intervention and typically map back to processor core power states. States for
processor core include Normal (C0, C1).
The processor core implements two software interfaces for requesting low power
states: MWAIT instruction extensions with sub-state specifies and P_LVLx reads to the
ACPI P_BLK register block mapped in the processor core’s I/O address space. The
P_LVLx I/O reads are converted to equivalent MWAIT C-state requests inside the
processor core and do not directly result in I/O reads on the processor core bus. The
monitor address does not need to be setup before using the P_LVLx I/O read interface.
The sub-state specifications used for each P_LVLx read can be configured in a software
programmable MSR by BIOS.
states: MWAIT instruction extensions with sub-state specifies and P_LVLx reads to the
ACPI P_BLK register block mapped in the processor core’s I/O address space. The
P_LVLx I/O reads are converted to equivalent MWAIT C-state requests inside the
processor core and do not directly result in I/O reads on the processor core bus. The
monitor address does not need to be setup before using the P_LVLx I/O read interface.
The sub-state specifications used for each P_LVLx read can be configured in a software
programmable MSR by BIOS.
The Cx state ends due to a break event. Based on the break event, the processor
returns the system to C0. The following are examples of such break events:
returns the system to C0. The following are examples of such break events:
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Any unmasked interrupt goes active