IBM Intel Xeon E5506 46M1079 User Manual
Product codes
46M1079
Features
134
Intel
®
Xeon
®
Processor 5500 Series Datasheet, Volume 1
7.2.1.2
C1/C1E State
C1/C1E is a low power state entered when all threads within a core execute a HLT or
MWAIT(C1E) instruction. The processor thread will transition to the C0 state upon
occurrence of an interrupt or an access to the monitored address if the state was
entered via the MWAIT instruction. RESET# will cause the processor to initialize itself
and return to C0.
MWAIT(C1E) instruction. The processor thread will transition to the C0 state upon
occurrence of an interrupt or an access to the monitored address if the state was
entered via the MWAIT instruction. RESET# will cause the processor to initialize itself
and return to C0.
A System Management Interrupt (SMI) handler will return execution to either Normal
state or the C1/C1E state. See the Intel® 64 and IA-32 Architectures Software
Developer's Manual, Volume III: System Programmer's Guide for more information.
state or the C1/C1E state. See the Intel® 64 and IA-32 Architectures Software
Developer's Manual, Volume III: System Programmer's Guide for more information.
While in C1/C1E state, the processor will process bus snoops and snoops from the
other threads.
other threads.
To operate within specification, BIOS must enable the C1E feature for all installed
processors.
processors.
7.2.1.3
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 core
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.
read to the P_BLK or an MWAIT(C3) instruction. Before entering core C3, the core
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 QuickPath Interconnect 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.
when the processor detects a snoop on the Intel QuickPath Interconnect 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.
7.2.1.4
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 it
state. The processor achieves additional power savings in the core C6 state.
the P_BLK or an MWAIT(C6) instruction. Before entering core C6, the processor saves it
state. The processor achieves additional power savings in the core C6 state.
7.2.2
Package Power State Descriptions
The package supports C0, C1/C1E, C3, and C6 power states. 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 below.
is automatically resolved by the processor depending on the core power states and
permission from the rest of the system as described below.
7.2.2.1
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 in C0.
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 in C0.
7.2.2.2
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
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