[erlang-questions] wierd:statistic(runtime) and statistic(wall_clock)

junli gu <>
Sat May 9 04:32:09 CEST 2009


we have two ways to get time :statistic(*runtime*) and
statistic(wall_clock).I have not find any exact desciption about the two
methods.
Some one have guessed:"Since erlang is not
guaranteed to have 100% of your CPU time, *runtime* would be the actual
amount
of processing time used by erlang. "wall_clock" time is simply recording the

actual time the process started and the actual time the process ended and
giving you the difference in "real time" ."

So we can came to the conclusion that *runtime* is less than  wall_clock.I
did some experiments to verify this,the result is really wired that I can't
understand:  *runtime* is probably both more or less than  wall_clock!
Waht's happenging? Would some one explain this?
process spawn average time =*runtime* <wall_clock> us
process spawn average time =1.5 <3.2> us
process spawn average time =3.44 <2.5> us

just wondering how to get the exact time that my process needed……

-- 
************************************************
Gu Junli--谷俊丽
PHD Candidate of Tsinghua University
Beijing 100084,China
Tel: 86-10-62795139

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