GR740-UM-DS, Nov 2017, Version 1.7
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GR740
26
LEON4 Statistics Unit (Performance Counters)
26.1
Overview
The LEON4 Statistics Unit (L4STAT) is used count events in the LEON4 processor and the AHB bus,
in order to create performance statistics for various software applications.
L4STAT consists of sixteen 32-bit counters that increment on a selected event. The counters roll over
to zero when reaching their maximum value, but can also be automatically cleared on reading to facil-
itate statistics building over longer periods. Each counter has a control register where the event type is
selected. The control registers also indicates which particular processor core is monitored. The table
435 below shows the event types that can be monitored.
Table 435.
Event types and IDs
ID
Event description
Processor events:
0x00
Instruction cache miss
0x01
Instruction MMU TLB miss
0x02
Instruction cache hold
0x03
Instruction MMU hold
0x08
Data cache (read) miss
0x09
Data MMU TLB miss
0x0A
Data cache hold
0x0B
Data MMU hold
0x10
Data write buffer hold
0x11
Total instruction count
0x12
Integer instructions
0x13
Floating-point unit instruction count
0x14
Branch prediction miss
0x15
Execution time, excluding debug mode
0x17
AHB utilization (per AHB master)
0x18
AHB utilization (total, master/CPU selection is ignored)
0x22
Integer branches
0x28
CALL instructions
0x30
Regular type 2 instructions
0x38
LOAD and STORE instructions
0x39
LOAD instructions
0x3A
STORE instructions
AHB events (counted via LEON4 Debug Support Unit):
0x40
AHB IDLE cycles. Filtered on CPU/AHBM if SU(1) = ‘1
0x41
AHB BUSY cycles. Filtered on CPU/AHBM if SU(1) = ‘1
0x42
AHB NON-SEQUENTIAL transfers. Filtered on CPU/AHBM if SU(1) = ‘1
0x43
AHB SEQUENTIAL transfers. Filtered on CPU/AHBM if SU(1) = ‘1
0x44
AHB read accesses. Filtered on CPU/AHBM if SU(1) = ‘1
0x45
AHB write accesses. Filtered on CPU/AHBM if SU(1) = ‘1
0x46
AHB byte accesses. Filtered on CPU/AHBM if SU(1) = ‘1
0x47
AHB half-word accesses. Filtered on CPU/AHBM if SU(1) = ‘1
0x48
AHB word accesses. Filtered on CPU/AHBM if SU(1) = ‘1
0x49
AHB double word accesses. Filtered on CPU/AHBM if SU(1) = ‘1