[Python-Dev] User + sys time bigger than real time, in case of no real parallelism
stefanrin at gmail.com
Sun Feb 5 03:58:51 EST 2017
> That is usually what I can expect in case of tasks executed in parallel on
> different CPUs. But my example should not be the case, due to the GIL. What
> am I missing? Thank you very much, and sorry again for the OT :(
With such finely intermingled thread activity, there might be a fair
bit of spinlock spinning involved. Additionally, I suspect that the
kernel does not track CPU time at microsecond precision and will tend
to round the used times up.
Obviously, this is not a reasonable way to use threads. The example is
only effective at producing lots of overhead.
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