[LLVMdev] How to measure the overhead of instrumented code

[Caldarale, Charles R]

> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
> On Behalf Of John Criswell
> Subject: Re: [LLVMdev] How to measure the overhead of instrumented code

> > To measure the pressure of instruction cache, I want to replace the instrumented
> > source code as nop (with length equals the length of instrumented source code). 

> If you know the length of your instrumentation in bytes, you could generate 
> inline assembly code that inserts the correct number of NOP instructions.

Except that current Intel CPUs include a micro-op cache, where the NOPs pretty much disappear; this is no longer a simple problem.  VTune or PAPI are your best bet.

 - Chuck


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