Uncore Manual
Reference Number: 329468-002 129
Uncore Performance Monitoring
Power Control (PCU) Performance Monitoring
FREQ_TRANS_CYCLES
• Title: Cycles spent changing Frequency
• Category: FREQ_TRANS Events
• Event Code: 0x60
• Max. Inc/Cyc:. 1, Register Restrictions: 0-3
• Definition: Counts the number of cycles when the system is changing frequency. This can not be
filtered by thread ID. One can also use it with the occupancy counter that monitors number of
threads in C0 to estimate the performance impact that frequency transitions had on the system.
MEMORY_PHASE_SHEDDING_CYCLES
• Title: Memory Phase Shedding Cycles
• Category: MEMORY_PHASE_SHEDDING Events
• Event Code: 0x2f
• Max. Inc/Cyc:. 1, Register Restrictions: 0-3
• Definition: Counts the number of cycles that the PCU has triggered memory phase shedding.
This is a mode that can be run in the iMC physicals that saves power at the expense of additional
latency.
• NOTE: Package C1
PKG_C_EXIT_LATENCY
• Title: Package C State Exit Latency
• Category: PKG_C_STATE_TRANSITION Events
• Event Code: 0x26
• Extra Select Bit: Y
• Max. Inc/Cyc:. 1, Register Restrictions: 0-3
• Definition: Counts the number of cycles that the package is transitioning from package C2 to C3.
• NOTE: This can be used in conjunction with edge detect to count C3 entrances.
POWER_STATE_OCCUPANCY
• Title: Number of cores in C-State
• Category: POWER_STATE_OCC Events
• Event Code: 0x80
• Max. Inc/Cyc:. 8, Register Restrictions: 0-3
• Definition: This is an occupancy event that tracks the number of cores that are in the chosen C-
State. It can be used by itself to get the average number of cores in that C-state with threshhold-
ing to generate histograms, or with other PCU events and occupancy triggering to capture other
details.
PROCHOT_EXTERNAL_CYCLES
• Title: External Prochot
• Category: PROCHOT Events
• Event Code: 0x0a
• Max. Inc/Cyc:. 1, Register Restrictions: 0-3
Table 2-127. Unit Masks for POWER_STATE_OCCUPANCY
Extension
umask
[15:8]
Description
CORES_C0 b01000000 C0 and C1
CORES_C3 b10000000 C3
CORES_C6 b11000000 C6 and C7