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I have a hard time understanding the math in vtune sampling result, Example:

Instruction retired - 2,920

ClockTicks - 1574

Cycle per retired Instruction - 1.214

If 2920 instruction execute and they take 1.214 cycle this add up to 3539 clockTicks, not 1574.

I didn't find in the help file an explaination on this.

Thanks any clarifying,

Stephan

PS: I asked this on the premier site, but wonder if any of you got the same math or understanding problem?

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2920 instructions executed in 1574 cycle.

1574 / 2920 = .539 CPI

How do you guy get to 1.214 ;)

Stephan

Instruction retired - 2,920

ClockTicks - 1574

Cycle per retired Instruction - 1.214

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In your case the sample after values for clockticks and instructions retired are 346189 and 92150 respectively. So

Total events for clockticks for the hightlighted region = 346189 * 1184

Total events for instructions retired for the hightlighted region = 92150 * 4154

Thus CPI = 1.071

If you want the VTune analyzer to show you the number of events and not samples in the source view then right click anywhere in the source view and select View Events As -> Sample Counts

Birju

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Ratios are always computed based on event values i.e. samples * sample after value and not on samples. This is to because VTune lets you configure events so that they have different sample after values. When computing ratios, they need to be normalized to make any sense. So yes, you can choose to see samples collected for an event instead of event values but ratios will always be based on event values.

Susmita

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