IBM PowerPC 750GX User Manual page 75

The following tables list the selectable events and their encodings:
• Table 11-2, PMC1 Events—MMCR0[19:25] Select Encodings, on page 352.
• Table 11-3, PMC2 Events—MMCR0[26:31] Select Encodings, on page 352.
• Table 11-4, PMC3 Events—MMCR1[0:4] Select Encodings, on page 353.
• Table 11-5, PMC4 Events—MMCR1[5:9] Select Encodings, on page 354.
The PMC registers can be accessed with mtspr and mfspr using following SPR numbers:
• PMC1 is SPR 953
• PMC2 is SPR 954
• PMC3 is SPR 957
• PMC4 is SPR 958
OV
0 1 2 3 4 5 6
Bits Field Name
0 OV
1:31 Counter Value
User Performance-Monitor Counter Registers (UPMCn)
The contents of the PMC1–PMC4 are reflected to UPMC1–UPMC4, which can be read by user-level soft-
ware. The UPMC registers can be read with mfspr using the following SPR numbers:
• UPMC1 is SPR 937
• UPMC2 is SPR 938
• UPMC3 is SPR 941
• UPMC4 is SPR 942
Sampled Instruction Address Register (SIA)
The Sampled Instruction Address Register (SIA) is a supervisor-level register that contains the effective
address of an instruction executing at or around the time that the processor signals the performance-monitor
interrupt condition.
If the performance-monitor interrupt is triggered by a threshold event, the SIA contains the exact instruction
(called the sampled instruction) that caused the counter to overflow.
If the performance-monitor interrupt was caused by something besides a threshold event, the SIA contains
the address of the last instruction completed during that cycle. SIA can be accessed with the mtspr and
mfspr instructions using SPR 955.
0 1 2 3 4 5 6
gx_02.fm.(1.2)
March 27, 2006
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Overflow. When this bit is set it indicates that this counter has reached its maximum
value.
Indicates the number of occurrences of the specified event.
Instruction Address
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
IBM PowerPC 750GX and 750GL RISC Microprocessor
Counter Value
Description
User's Manual
Programming Model
Page 75 of 377