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sh22iyer
Beginner
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Interpreting Sampling results

Hi,

I have spent quite a lot of time on this, but am obviously missing from elementary! I did a sampling run with the following parameters :-

1) Sampling interval = 1 ms (this is the default)
2) Events to sample = Clockticks after 300000 and Instructions Retired after 300000 (modified the default values 3000000)

Now the run shows me for the top 2 functions :-

1)
function1()
Clocktick samples = 1061
Instruction retired samples = 871
Clockticks per instruction retired = 1.218
Clockticks events = 1061*300000
Instructions retired events = 871*300000

2)
function2()
Clocktick samples = 715
Instruction retired samples = 411
Clockticks per instruction retired = 1.740

This is what I understand :-

- After 300000 clockticks, a sample is taken. 1061 such samples found the Instruction Pointer(IP) to be in function1() and 715 such samples found the IP in function2()
- After 300000 instructions, a sample is taken. 871 such samples found the IP to be in function1() and 411 suc samples found the IP in function2()

Now what I don't understand is how and why should the Clocktick samples and Instruction retired samples be divided? Aren't they totally unrelated?

If samples are taken after number of events, then what is the sampling interval (1ms) in time parameter for?

Thanks in advance!

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