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Vol. 3B 19-123

PERFORMANCE-MONITORING EVENTS

24H

Com-

bined 

mask 

from 

Table 

18-2 

and 

Table 

18-4

L2_LINES_IN.

(Core, Prefetch)

L2 cache misses.

This event counts the number of cache lines allocated in the 

L2 cache. Cache lines are allocated in the L2 cache as a 

result of requests from the L1 data and instruction caches 

and the L2 hardware prefetchers to cache lines that are 

missing in the L2 cache. 
This event can count occurrences for this core or both cores. 

It can also count demand requests and L2 hardware 

prefetch requests together or separately.

25

H

See 

Table 

18-2

L2_M_LINES_IN.

(Core)

L2 cache line 

modifications.

This event counts whenever a modified cache line is written 

back from the L1 data cache to the L2 cache. 
This event can count occurrences for this core or both cores.

26

H

See 

Table 

18-2 

and 

Table 

18-4

L2_LINES_OUT.

(Core, Prefetch)

L2 cache lines evicted. This event counts the number of L2 cache lines evicted. 

This event can count occurrences for this core or both cores. 

It can also count evictions due to demand requests and L2 

hardware prefetch requests together or separately.

27

H

See 

Table 

18-2 

and 

Table 

18-4

L2_M_LINES_OUT.(Core, 

Prefetch)

Modified lines evicted 

from the L2 cache.

This event counts the number of L2 modified cache lines 

evicted. These lines are written back to memory unless they 

also exist in a modified-state in one of the L1 data caches. 
This event can count occurrences for this core or both cores. 

It can also count evictions due to demand requests and L2 

hardware prefetch requests together or separately.

28

H

Com-

bined 

mask 

from 

Table 

18-2 

and 

Table 

18-5

L2_IFETCH.(Core, Cache 

Line State)

L2 cacheable 

instruction fetch 

requests.

This event counts the number of instruction cache line 

requests from the IFU. It does not include fetch requests 

from uncacheable memory. It does not include ITLB miss 

accesses. 
This event can count occurrences for this core or both cores. 

It can also count accesses to cache lines at different MESI 

states.

29

H

Combin

ed mask 

from 

Table 

18-2

Table 

18-4

and 

Table 

18-5

L2_LD.(Core, Prefetch, 

Cache Line State)

L2 cache reads.

This event counts L2 cache read requests coming from the 

L1 data cache and L2 prefetchers. 
The event can count occurrences:
• For this core or both cores.

• Due to demand requests and L2 hardware prefetch 

requests together or separately.

• Of accesses to cache lines at different MESI states.

2A

H

See 

Table 

18-2 

and 

Table 

18-5

L2_ST.(Core, Cache Line 

State)

L2 store requests.

This event counts all store operations that miss the L1 data 

cache and request the data from the L2 cache. 
The event can count occurrences for this core or both cores. 

It can also count accesses to cache lines at different MESI 

states.

Table 19-23.  Non-Architectural Performance Events in Processors Based on Intel® Core™ Microarchitecture (Contd.)

Event 

Num

Umask

Value

Event Name 

Definition

Description and

Comment