Re: Objective-C and Smalltalk; speed of message send

[Marcel Weiher]

> > Apart from what Richard said, it seems you are primarily measuring 
> > the speed of the getrusage() system call that clock() tends to be 
> > based on...
>
> Actually no ... if you examine the code carefully, you will see that 
> clock() is used to time operations (one call to clock() before the 
> operation and one call after), but that the only operation actually 
> used for presenting a result is the fist one which takes over a second 
> to execute ...  so the execution time of clock() is insignificant.

Ahh, yes, you're right, of course.  "Please engage brain before putting 
mouth into gear".  Fortunately, I hedged with "seems" ;-)


> > Actual message passing speed for a constant receiver is around 50 ns 
> > on 1 Ghz G4, with a third of that going to inter-module calling 
> > overhead.  So around 20 million message sends per second.  Squeak on 
> > the same system is significantly slower.
>
> That's interesting.
> Is that with the apple or gnu runtime?

Apple runtime.

> Is that repeated uses of the same message to objects of the same class?

Yes, constant receiver and constant message as well.

>   I ask because the apple runtime caches those and is much faster if 
> you benchmark that than if you benchmark against a large variety of 
> different methods.

Yes, though the method cache tends to be pretty effective, and they 
also have further caching in the classes themselves, so primary cache 
failure apparently does not mean a full table-walk.  Though I have to 
admit that I always found those parts somewhat obscure.

Cheers,

Marcel


--
Marcel Weiher                           Metaobject Software Technologies
marcel@metaobject.com           www.metaobject.com
Metaprogramming for the Graphic Arts.   HOM, IDEAs, MetaAd etc.
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