Simulation Time and actual time Confusion

[mike anastasakis]

Ok , so I ran the parsec blackscholes benchmark which gave me the stats. 

• Total time spent in ROI : 0.007
  
• Leaving ROI after 1198.61 seconds
• Elapsed time : 469.17 seconds

I created a python script which printed a message every 1 millisecond The script was called 24 times which is 24 milliseconds. The message was printed 7 times while in ROI which makes sense as ROI lasted 7 seconds. But where does the total of 24 millisecond comes from ? 
From the results we have how do I realise what is the total time of execution of the benchmark ? 

Thanks in advance

[Wim Heirman]

Mike,

Time can advance during warmup (before ROI) as well, usually at one clock cycle per instruction, which is why you are seeing 24 ms of total application time. The ROI itself took 7 ms which should also be the value in sim.out. Note that the timing before ROI is not accurate (real IPC is usually not equal to one), so if you want to simulate total application time rather than just ROI, do not use the --roi flag (or use --no-roi when using benchmarks/run-sniper).

Regards,

Wim

 

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[mike anastasakis]

I figured that out and used the commant --no-roi . The results that I posted above are with the option --no-roi. I guess that the benchmark small blackscholes ran for a total of 27 milliseconds . Since I used -no-roi and i saw a total of 27 messages .
With this assumption my question is what does this time represent then 

• Leaving ROI after 1198.61 seconds

And did my benchamrk trully ran for only 27 milliseconds only ? Thanks in advance

[Wim Heirman]

You should look at the value in sim.out, but that should be 27 ms.

The "Total time spent in ROI" message is generated by the benchmark, based on it calling gettimeofday() which should return simulated time to the benchmark.

The other messages should have [SNIPER] prefixed and are generated by the simulator itself, they are in walltime (simulation time).

-Wim

[mike anastasakis]

I just saw the value at sim.out and you are correct approximately it is 27 ms . I  was confused by the time the simulator takes and the actual benchmark runs . Since the whole simulation lasted  for like 15 minutes i was not convinced that the actualy benchamrk runtime was a total of 27 ms  but I guess that's the case . Thanks for your answer Wim!

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