Intel E5-2600, CM8062101038606 Efficient Performance Indicator Read, Acpi P-T Notify Write & Read

2.5.2.6.28Efficient Performance Indicator Read

The Efficient Performance Indicator (EPI) Read provides an indication of the total number of productive cycles. Specifically, these are the cycles when the processor is engaged in any activity to retire instructions and as a result, consuming energy. Any power management entity monitoring this indicator should sample it at least once every 4 seconds to enable detection of wraparounds. Refer to the processor Intel® 64 and IA-32 Architectures Software Developer’s Manual (SDM) Volumes 1, 2, and 3, for details on programming the Energy/Performance Bias (MSR_MISC_PWR_MGMT) register to set the ‘Energy Efficiency’ policy of the processor.

Figure 2-38. Efficient Performance Indicator Read

31 0

Efficient Performance Cycles

Efficient Performance Indicator Data

2.5.2.6.29ACPI P-T Notify Write & Read

This feature enables the processor turbo capability when used in conjunction with the PECI package RAPL or power limit. When the BMC sets the package power limit to a value below TDP, it also determines a new corresponding turbo frequency and notifies the OS using the ‘ACPI Notify’ mechanism as supported by the _PPC or performance present capabilities object. The BMC then notifies the processor PCU using the PECI ‘ACPI P-T Notify’ service by programming a new state that is one p-state below the turbo frequency sent to the OS via the _PPC method.

When the OS requests a p-state higher than what is specified in bits [7:0] of the PECI ACPI P-T Notify data field, the CPU will treat it as request for P0 or turbo. The PCU will use the IA32_ENERGY_PERFORMANCE_BIAS register settings to determine the exact extent of turbo. Any OS p-state request that is equal to or below what is specified in the PECI ACPI P-T Notify will be granted as long as the RAPL power limit does not impose a lower p-state. However, turbo will not be enabled in this instance even if there is headroom between the processor energy consumption and the RAPL power limit.

This feature does not affect the Thermal Monitor behavior of the processor nor is it impacted by the setting of the power limit clamp mode bit.

Figure 2-39. ACPI P-T Notify Data

31		8	7	0
	Reserved		New P1 state

ACPI P-T Notify Data

58	Intel® Xeon® Processor E5-1600/E5-2600/E5-4600 Product Families
	Datasheet Volume One