[parsec-users] what do 'user', 'real' time refer to

Vijay Thiruvengadam vijayaragha2 at wisc.edu
Mon Dec 26 19:26:37 EST 2011


Hello

I am a first year grad student. I am running the PARSEC benchmark Fluidanimate on a Intel QuadCore computer and am trying to make sense of the result obtained.

I notice that I get the 'real', 'user' and 'sys' time as the outputs on running the benchmark with X number of threads. I keep changing the number of threads and observe the result. This question might seem too basic but I am not exactly sure what the 'real', 'user' and 'sys' terms refer to.

As far as  understand, 'real' is the time spent in the parallelized phase of the benchmark(region of interest) and 'user' is the time spent in the initialization and shutdown sequence. 'sys' probably refers to the operating system overhead. Did I get this right?

Also, I observe that the 'user' time always increases with increase in number of threads. Why is that?

Thanks
Vijay


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