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SubjectRe: Measuring execution time
Mark Cuss wrote:

> I am working on optimizing some software and would like to be able to
> measure how long an instruction takes (down to the clock cycle of the CPU).
> I recall reading somewhere about a kernel time measurement called a "Jiffy"
> and figured that it would probably apply to this.
> If anyone has any tips on how to figure out how to do this I'd really
> appreciate it.

Jiffies are quite coarse-grained. On x86 you want the rdtsc instruction, while
on ppc you want mfrtcu/mfrtcl or mftbu/mftb depending on the version of the
chip. These are used as inline assembly, and if you do a google search you
should be able to find code snippets.


Chris Friesen | MailStop: 043/33/F10
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