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

Michael Haupt mhaupt at gmail.com
Thu Apr 28 17:53:24 CEST 2011


Hi Alex,

On 28 April 2011 18:14, Alexandre Bergel <alexandre.bergel at me.com> wrote:
>> Or have a VM that is not Squeak, and perhaps use a language that is not used in the style Smalltalk is (7 lines of code per method, right?).
>
> Yes, but there hasn't been a major change on the VM front since I started Smalltalk. Cog is the notable exception, but the assumption I made without Cog remains valid with Cog.

do you mean "on the *Smalltalk* VM front"? I'm pretty sure you do. :-)

> 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 ...

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

> I am simply focusing on sending messages, which is in my opinion, the essence of the OO executing model.

Yup, good point.

Best,

Michael



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