Intel 64 and IA-32 Architectures Software Developers Manual Volume 3B, System Programming Guide Part 2

Table Of Contents
Vol. 3 A-215
PERFORMANCE-MONITORING EVENTS
35H PIPELINE_
FLUSHES_DUE_
TO_WRONG_
BRANCH_
PREDICTIONS
(Counter 0)
Number of pipeline
flushes due to wrong
branch predictions
resolved in either the E-
stage or the WB-stage
The count includes any pipeline flush
due to a branch that the pipeline did
not follow correctly. It includes cases
where a branch was not in the BTB,
cases where a branch was in the BTB
but was mispredicted, and cases
where a branch was correctly
predicted but to the wrong address.
Branches are resolved in either the
Execute stage (E-stage) or the
Writeback stage (WB-stage). In the
later case, the misprediction penalty
is larger by one clock. The difference
between the 35H event count in
counter 0 and counter 1 is the
number of E-stage resolved
branches.
35H PIPELINE_
FLUSHES_DUE_
TO_WRONG_
BRANCH_
PREDICTIONS_
RESOLVED_IN_
WB-STAGE
(Counter 1)
Number of pipeline
flushes due to wrong
branch predictions
resolved in the WB-
stage
See note for event 35H (Counter 0).
36H MISALIGNED_
DATA_MEMORY_
REFERENCE_ON_
MMX_
INSTRUCTIONS
(Counter 0)
Number of misaligned
data memory references
when executing MMX
instructions
36H PIPELINE_
ISTALL_FOR_MMX_
INSTRUCTION_
DATA_MEMORY_
READS
(Counter 1)
Number clocks during
pipeline stalls caused by
waits form MMX
instruction data memory
reads
T3:
Table A-19. Events That Can Be Counted with Pentium Processor
Performance-Monitoring Counters (Contd.)
Event
Num.
Mnemonic Event
Name Description Comments