Intel E5-1600, CM8062101038606 Power Control Register Unit Calculations, Package Power SKU Read

Table 2-9. Power Control Register Unit Calculations

Unit Field	Value Calculation	Default Value
Time	1s / 2TIME UNIT	1s / 210 = 976 µs
Energy	1J / 2ENERGY UNIT	1J / 216 = 15.3 µJ
Power	1W / 2POWER UNIT	1W / 23 = 1/8 W

2.5.2.6.14Package Power SKU Read

This read allows the PECI host to access the minimum, Thermal Design Power and maximum power settings for the processor package SKU. It also returns the maximum time interval or window over which the power can be sustained. If the power limiting entity specifies a power limit value outside of the range specified through these settings, power regulation cannot be guaranteed. Since this data is 64 bits wide, PECI facilitates access to this register by allowing two requests to read the lower 32 bits and upper 32 bits separately as shown in Table 2-8. Power units for this read are determined as per the Package Power SKU Unit settings described in

Section 2.5.2.6.13.

‘Package Power SKU data’ is programmed by the PCU firmware during boot time based on SKU dependent power-on default values set during manufacturing. The TDP package power specified through bits [14:0] in Figure 2-28is the maximum value of the ‘Power Limit1’ field in Section 2.5.2.6.26 while the maximum package power in bits [46:32] is the maximum value of the ‘Power Limit2’ field.

The minimum package power in bits [30:16] is applicable to both the ‘Power Limit1’ & ‘Power Limit2’ fields and corresponds to a mode when all the cores are operational and in their lowest frequency mode. Attempts to program the power limit below the minimum power value may not be effective since BIOS/OS, and not the PCU, controls disabling of cores and core activity.

The ‘maximum time window’ in bits [54:48] is representative of the maximum rate at which the power control unit (PCU) can sample the package energy consumption and reactively take the necessary measures to meet the imposed power limits.

Programming too large a time window runs the risk of the PCU not being able to monitor and take timely action on package energy excursions. On the other hand, programming too small a time window may not give the PCU enough time to sample energy information and enforce the limit. The minimum value of the ‘time window’ can be obtained by reading bits [21:15] of the PWR_LIMIT_MISC_INFO CSR using the PECI RdPCIConfigLocal() command.

Intel® Xeon® Processor E5-1600/E5-2600/E5-4600 Product Families	51
Datasheet Volume One