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19-206 Vol. 3B

PERFORMANCE-MONITORING EVENTS

The count includes only L2 cacheable 

instruction fetches; it does not include UC 

instruction fetches.
It does not include ITLB miss accesses.

29H

L2_LD

MESI

0FH

Number of L2 data loads.
This event indicates that a normal, unlocked, 

load memory access was received by the L2.
It includes only L2 cacheable memory 

accesses; it does not include I/O accesses, 

other nonmemory accesses, or memory 

accesses such as UC/WT memory accesses.
It does include L2 cacheable TLB miss 

memory accesses.

2AH

L2_ST

MESI

0FH

Number of L2 data stores.
This event indicates that a normal, unlocked, 

store memory access was received by the 

L2.
it indicates that the DCU sent a read-for-

ownership request to the L2. It also includes 

Invalid to Modified requests sent by the DCU 

to the L2.
It includes only L2 cacheable memory 

accesses; it does not include I/O accesses, 

other nonmemory accesses, or memory 

accesses such as UC/WT memory accesses.
It includes TLB miss memory accesses.

24H

L2_LINES_IN

00H

Number of lines allocated in the L2.

26H

L2_LINES_OUT

00H

Number of lines removed from the L2 for 

any reason.

25H

L2_M_LINES_INM 00H

Number of modified lines allocated in the L2.

27H

L2_M_LINES_

OUTM

00H

Number of modified lines removed from the 

L2 for any reason.

2EH

L2_RQSTS

MESI

0FH

Total number of L2 requests.

21H

L2_ADS

00H

Number of L2 address strobes.

22H

L2_DBUS_BUSY

00H

Number of cycles during which the L2 cache 

data bus was busy.

23H

L2_DBUS_BUSY_

RD

00H

Number of cycles during which the data bus 

was busy transferring read data from L2 to 

the processor.

External 

Bus Logic 

(EBL)

2

62H

BUS_DRDY_

CLOCKS

00H 

(Self)
20H 

(Any)

Number of clocks during which DRDY# is 

asserted.
Utilization of the external system data bus 

during data transfers.

Unit Mask = 00H counts bus clocks 

when the processor is driving 

DRDY#.
Unit Mask = 20H counts in 

processor clocks when any agent is 

driving DRDY#.

Table 19-37.  Events That Can Be Counted with the P6 Family Performance-Monitoring Counters (Contd.)

Unit

Event 

Num.

Mnemonic Event 

Name

Unit 

Mask Description

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