What does PAPI_FP_INS really count?

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What does PAPI_FP_INS really count?

Postby arrazem » Thu Apr 29, 2010 2:44 am

Hi:

I'm doing dynamic instrumentation of code on an Intel Xeon processor. I'm trying to count the # of FP instructions.
I can't seem to get the instrumentation's count to make even closely to what PAPI_FP_INS is giving me.

So, I was wondering what PAPI_FP_INS is really counting. Does it count floating point loads and stores?
What does PAPI consider as an FP instruction?
arrazem
 
Posts: 9
Joined: Mon Jan 04, 2010 4:49 pm

Re: What does PAPI_FP_INS really count?

Postby arrazem » Wed May 05, 2010 1:22 pm

UPDATE:

So, after alot of experiments, it turns out that on this CPU (Intel Xeon), PAPI_FP_INS counts all FP instructions that produce an FP value(to a register or mem), but it does not count the following kinds of FP instruction:
1. No loads/stores (MOV instructions) involving FP values
2. No FP instructions that don't produce a value such as a FP compare

Hope that would help someone in the future.
arrazem
 
Posts: 9
Joined: Mon Jan 04, 2010 4:49 pm


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