14-38 Vol. 3B
POWER AND THERMAL MANAGEMENT
MSR_DRAM_ENERGY_STATUS is a read-only MSR. It reports the actual energy use for the DRAM domain. This MSR
is updated every ~1msec.
•
Total Energy Consumed (bits 31:0): The unsigned integer value represents the total amount of energy
consumed since that last time this register is cleared. The unit of this field is specified by the “Energy Status
Units” field of MSR_RAPL_POWER_UNIT.
MSR_DRAM_POWER_INFO is a read-only MSR. It reports the DRAM power range information for RAPL usage. This
MSR provides maximum/minimum values (derived from electrical specification), thermal specification power of the
DRAM domain. It also provides the largest possible time window for software to program the RAPL interface.
•
Thermal Spec Power (bits 14:0): The unsigned integer value is the equivalent of thermal specification power
of the DRAM domain. The unit of this field is specified by the “Power Units” field of MSR_RAPL_POWER_UNIT.
•
Minimum Power (bits 30:16): The unsigned integer value is the equivalent of minimum power derived from
electrical spec of the DRAM domain. The unit of this field is specified by the “Power Units” field of
MSR_RAPL_POWER_UNIT.
•
Maximum Power (bits 46:32): The unsigned integer value is the equivalent of maximum power derived from
the electrical spec of the DRAM domain. The unit of this field is specified by the “Power Units” field of
MSR_RAPL_POWER_UNIT.
•
Maximum Time Window (bits 53:48): The unsigned integer value is the equivalent of largest acceptable
value to program the time window of MSR_DRAM_POWER_LIMIT. The unit of this field is specified by the “Time
Units” field of MSR_RAPL_POWER_UNIT.
MSR_DRAM_PERF_STATUS is a read-only MSR. It reports the total time for which the package was throttled due to
the RAPL power limits. Throttling in this context is defined as going below the OS-requested P-state or T-state. It
has a wrap-around time of many hours. The availability of this MSR is platform specific (see Chapter 35).
Figure 14-41. MSR_DRAM_ENERGY_STATUS MSR
Figure 14-42. MSR_DRAM_POWER_INFO Register
Figure 14-43. MSR_DRAM_PERF_STATUS MSR
63
0
Reserved
Total Energy Consumed
31
32
Reserved
63
31 30
15
0
Thermal Spec Power
48 47
32
54 53
46
14
Maximum Power
16
Maximum Time window
Minimum Power
63
0
Reserved
Accumulated DRAM throttled time
31
32
Reserved