[Pharo-project] Counting Messages as a Proxy for Average Execution Time in Pharo

Alexandre Bergel alexandre.bergel at me.com
Fri Apr 29 00:08:19 CEST 2011


>> Most profilers, including MessageTally, count stack frames at a regular interval. This is doomed to be inexact, non-deterministic and non-portable, and so, whatever the effort you will put in the thread scheduling, memory management or whatsoever.
> 
> I think you're being a bit harsh on stack sampling there. It is exact
> enough to drive optimisation in some really high-performance VMs. It
> is also deterministic enough to yield data leading to very good
> performance results in those VMs. Whether focusing on counting
> messages instead of taking samples is more beneficial would have to be
> determined by experiment ...

Yes, 25 pages of experiment :-)

> What you mean with "non-portable" I do not understand.

The information about the execution time contained in your profile cannot be compared with a new profile realized on a different machine, with a different CPU.

Alexandre

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Alexandre Bergel  http://www.bergel.eu
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