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Intel_C_Intel
Employee
53 Views

Calculating Branch Mispredicts on IPF

Can someone please tell me the simplest way (if one exists) to calculate branch mispredicts on the Itanium 2 platform. Since there is no recipe for this ratio already in the tool, you are forced to go to the Events dialog and select from what appear to be many many branch event counters. I opted to grab "Branch Events" and "BE_BR_MISPRED_DETAIL-ANY".

I'm having trouble believing the output. Please help.
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1 Reply
bnshah
Beginner
53 Views

There is no easy way due to the complexity of the Itanium 2 branch prediction logic. Here is a forumula you can use. It will you the branch misprediction ratio. .

((BR_MISPRED_DETAIL.ALL.ALL_PRED - BR_MISPRED_DETAIL2.ALL.ALL_UNKNOWN_PRED) -
(BR_MISPRED_DETAIL.ALL.CORRECT_PRED - BR_MISPRED_DETAIL2.ALL.ALL_UNKNOWN_PATH_CORRECT_PRED) ) /
(BR_MISPRED_DETAIL.ALL.ALL_PRED - BR_MISPRED_DETAIL2.ALL.ALL_UNKNOWN_PRED)

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