Memory allocation performance

Joseph Koshy joseph.koshy at
Sat Feb 2 02:37:15 PST 2008

> I have tried it for measuring number of instructions. But I am in doubt
> that instructions is a correct counter for performance measurement as
> different instructions may have very different execution times depending
> on many reasons, like cache misses and current memory traffic. I have
> tried to use tsc to count CPU cycles, but got the error:
> # pmcstat -n 10000 -S "tsc" -O sample.out
> pmcstat: ERROR: Cannot allocate system-mode pmc with specification
> "tsc": Operation not supported
> What have I missed?

You cannot sample with the TSC since the TSC does not interrupt the CPU.
For CPU cycles you would probably want to use "p4-global-power-events";
see pmc(3).


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