Intel BX80601920 Data Sheet - Page 85

Features 7.2.1.3 7.2.1.4 7.2.2 7.2.2.1 7.2.2.2 7.2.2.3 While in C1/C1E state, the processor will process bus snoops and snoops from the other threads. C3 State Individual threads of the processor can enter the C3 state by initiating a P_LVL2 I/O read to the P_BLK or an MWAIT(C3) instruction. Before entering core C3, the processor flushes the contents of its caches. Except for the caches, the processor core maintains all its architectural state while in the C3 state. All of the clocks in the processor core are stopped in the C3 state. Because the core's caches are flushed, the processor keeps the core in the C3 state when the processor detects a snoop on the Intel QPI Link or when another logical processor in the same package accesses cacheable memory. The processor core will transition to the C0 state upon occurrence of an interrupt. RESET# will cause the processor core to initialize itself. C6 State Individual threads of the processor can enter the C6 state by initiating a P_LVL3 read to the P_BLK or an MWAIT(C6) instruction. Before entering Core C6, the processor saves core state data (such as, registers) to the last level cache. This data is retired after exiting core C6. The processor achieves additional power savings in the core C6 state. Package Power State Descriptions The package supports C0, C3, and C6 power states. Note that there is no package C1 state. The package power state is automatically resolved by the processor depending on the core power states and permission from the rest of the system as described in the following sections. Package C0 State This is the normal operating state for the processor. The processor remains in the Normal state when at least one of its cores is in the C0 or C1 state or when another component in the system has not granted permission to the processor to go into a low power state. Individual components of the processor may be in low power states while the package is in C0. Package C1/C1E State The package will enter the C1/C1E low power state when at least one core is in the C1/C1E state and the rest of the cores are in the C1/C1E or lower power state. The processor will also enter the C1/C1E state when all cores are in a power state lower than C1/C1E but the package low power state is limited to C1/C1E using the PMG_CST_CONFIG_CONTROL MSR. In the C1E state, the processor will automatically transition to the lowest power operating point (lowest supported voltage and associated frequency). When entering the C1E state, the processor will first switch to the lowest bus ratio and then transition to the lower VID. No notification to the system occurs upon entry to C1/C1E. Package C3 State The package will enter the C3 low power state when all cores are in the C3 or lower power state and the processor has been granted permission by the other component(s) in the system to enter the C3 state. The package will also enter the C3 state when all cores are in an idle state lower than C3 but other component(s) in the system have only granted permission to enter C3. Datasheet 85