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Understand the CPU Timestamp and OS Timestamp in Bottom-up and Top-down tabs of the profiler results

Abhishekv
Beginner
333 Views

I profiled an application and i saw the profiling was successful. I
seek for the top-down/bottom-up view in the profiler results. I
specifically try to understand the overlap between thread level
CPUTime and Running Time. I see a timeline where the time can be
chosen among Elapsed Time, CPU Timestamp and OS Timestamp. The
elapsed time starts at 0ms while the CPU Timestamp and OS Timestamp
start at a 14 digit number. Following are the questions with regard
to the same.

1. What is the meaning of 14 digit number - how is it computed or
how should it be understood? The pictures for the same are posted
as attachments.


2. How do i map the 14 digit to number the actual wall-clock time
based on time zones?

Setup:
I am using vtune-gui on the windows host
Running the target application the GuestOS(Ubuntu).
The profiling is done via ssh for the target application

Please find the helpful images attached

thank you
Abhishek

 

Images:

cpu_time_1.PNGcpu_time_2.PNG

0 Kudos
3 Replies
JyothisV_Intel
Moderator
288 Views

Hi,


Good day to you.


Thanks for posting in Intel Communities.


We are working on this internally to provide you with detailed information regarding the queries that you mentioned. We will get back to you with an update as soon as possible.


Regards,

Jyothis V James


Abhishekv
Beginner
245 Views

I wish to know the status of the query.

clevels
Employee
199 Views

Hello- I have looked into this and the CPU timestamp is displaying of Time Stamp Counter (TSC) register. For the OS Timestamp I am still researching, but most likely a return of clock_gettime() call. The absolute value of the clock is not necessarily of value because its origin is arbitrary for OS. And for CPU the TSC counts the number of CPU cycles since its reset. I am not sure it is necessary to map this to wall clock time. I am still looking into this and will follow up again. Thank you for your patience.


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