Uncore Manual

ManualsBrandsIntel ManualsOtherIntel Celeron Processor 766 MHz, 128K Cache, 66 MHz FSB

151

152

153

154

155

156

157

158

159

160

Uncore Performance Monitoring

Intel® QPI Link Layer Performance Monitoring

154 Reference Number: 329468-002

RxL_OCCUPANCY_NDR

• Title: RxQ Occupancy - NDR

• Category: RXQ Events

• Event Code: 0x1a

• Extra Select Bit: Y

• Max. Inc/Cyc:. 128, Register Restrictions: 0-3

• Definition: Accumulates the number of elements in the QPI RxQ in each cycle. Generally, when

data is transmitted across QPI, it will bypass the RxQ and pass directly to the ring interface. If

things back up getting transmitted onto the ring, however, it may need to allocate into this buffer,

thus increasing the latency. This event can be used in conjunction with the Flit Buffer Not Empty

event to calculate average occupancy, or with the Flit Buffer Allocations event to track average life-

time. This monitors NDR flits only.

RxL_OCCUPANCY_SNP

• Title: RxQ Occupancy - SNP

• Category: RXQ Events

• Event Code: 0x19

• Extra Select Bit: Y

• Max. Inc/Cyc:. 128, Register Restrictions: 0-3

• Definition: Accumulates the number of elements in the QPI RxQ in each cycle. Generally, when

data is transmitted across QPI, it will bypass the RxQ and pass directly to the ring interface. If

things back up getting transmitted onto the ring, however, it may need to allocate into this buffer,

thus increasing the latency. This event can be used in conjunction with the Flit Buffer Not Empty

event to calculate average occupancy, or with the Flit Buffer Allocations event to track average life-

time. This monitors SNP flits only.

TxL0P_POWER_CYCLES

• Title: Cycles in L0p

• Category: POWER_TX Events

• Event Code: 0x0d

• Max. Inc/Cyc:. 1, Register Restrictions: 0-3

• Definition: Number of QPI qfclk cycles spent in L0p power mode. L0p is a mode where we disable

1/2 of the QPI lanes, decreasing our bandwidth in order to save power. It increases snoop and data

transfer latencies and decreases overall bandwidth. This mode can be very useful in NUMA opti-

mized workloads that largely only utilize QPI for snoops and their responses. Use edge detect to

count the number of instances when the QPI link entered L0p. Link power states are per link and

per direction, so for example the Tx direction could be in one state while Rx was in another.

• NOTE: Using .edge_det to count transitions does not function if L1_POWER_CYCLES > 0.

Table 2-155. Unit Masks for RxL_OCCUPANCY_NDR

Extension

umask

[15:8]

Description

VN0 bxxxxxxx1 for VN0

VN1 bxxxxxx1x for VN1

Table 2-156. Unit Masks for RxL_OCCUPANCY_SNP