Intel D2500 DF8064101055400 Scheda Tecnica
Codici prodotto
DF8064101055400
106
Datasheet - Volume 1 of 2
7.2.5.5
Thread C4 State
Individual threads of the processor can enter the C4 state by initiating a P_LVL4 I/O
read to the P_BLK or an MWAIT(C4) instruction. If both processor threads are in C4,
the central power management logic will request that the entire processor enter the
Deeper Sleep low-power state.
To enable the level Intel Enhanced Deeper Sleep state, Dynamic Cache Sizing and Intel
Enhanced Deeper Sleep state fields must be configured in the
PMG_CST_CONFIG_CONTROL MSR.
7.2.6
Processor Core/ C-states Description
The following state descriptions assume that both threads are in common low power
state. For cases when only 1 thread is in a low power state, no change in Core/ Power
state will occur.
7.2.6.1
Core C0 State
The normal operating state of a core where code is being executed.
7.2.6.2
Core C1/C1E State
C1/C1E is a low power state entered when all threads within a core execute a HLT or
MWAIT(C1/C1E) instruction.
A System Management Interrupt (SMI) handler returns execution to either Normal
state or the C1/C1E state. Refer to the Intel® 64 and IA-32 Architecture Software
Developer’s Manual, Volume 3A/3B: System Programmer’s Guide for more information.
While a core is in C1/C1E state, it processes bus snoops and snoops from other
threads. For more information on C1E, Refer to “Package C1/C1E”.
7.2.6.3
C2 State
Individual threads of the dual-threaded processor core can enter TC2 state by initiating
a P_LVL2 I/O read to the P_BLK or an MWAIT (C2) instruction. Once both threads have
C2 as a common state, the processor core will transition to the C2 state; however, the
processor core will not issue a Stop-Grant Acknowledge special bus cycle unless the
STPCLK# pin is also asserted by the chipset.
While in the C2 state, the processor core will process bus snoops. The processor core
will enter a snoopable sub-state to process the snoop and return to the C2 state.
7.2.6.4
C4 State
Individual threads of a core can enter the C4 state by initiating a P_LVL2 I/O read to
the P_BLK or an MWAIT(C4) instruction. A core in C4 state flushes the contents of its
L1 instruction cache, L1 data cache, and L2 cache to the shared L3 cache, while
maintaining its architectural state. All core clocks are stopped at this point. Because the
core’s caches are flushed, the processor does not wake any core that is in the C4 state
when either a snoop is detected or when another core accesses cacheable memory.