[squeak-dev] Re: jitter (was: The Old Man)

Andreas Raab andreas.raab at gmx.de
Wed Apr 2 08:36:58 UTC 2008


goran at krampe.se wrote:
>> 	 thanks for informing about the state of jitter. Those 3 million
>> sends/sec more represents a nice pie of 30% better sends/sec. That jitter can
>> make team work with current interpreter? An updated and ported jitter, for lets
>> say 3dot10, you will say it sum performance near that 30% in sends?
> 
> If I remember correctly Jitter3 was actually a VM written in C++, Ian
> can correct me if I am wrong. And if my memory serves correctly it
> didn't show as impressive numbers in "real world scenarios" as compared
> to benchmarks simply due to the fact that most real world Squeak apps
> spend 50% of their time in primitives and those aren't affected.
> 
> (modulo my memory failing me of course)

Yes, that's my recollection too. J3 had portions that were compiled into 
native code (I remember that there were a few macros that one had to 
implement on each platform) but the main reason why it didn't show too 
much real-world improvements was (IIRC) that it didn't to context 
mapping and inline caches. Those are the places that *really* make a 
difference (context-mapping of course is hard without fixing blocks to 
be strictly lifo).

> My perception in all this is that Exupery is the *clearly* most
> promising speed technology we have available and it is getting faster
> and faster all the time. And it works together with the normal VM.

One of my problems with Exupery is that I've only seen claims about byte 
code speed and if you know where the time goes in a real-life 
environment then you know it ain't bytecodes. In other words, it seems 
to me that Exupery is optimizing the least significant portion of the 
VM. I'd be rather more impressed if it did double the send speed.

> The numbers Exupery shows today with normal Squeak are very impressive
> and the numbers Exupery shows in Huemul are even faster - due to some
> improvements that Guillermo could make due to the fact that he has full
> control of the design of the VM, if I understand it correctly.

Based on which benchmarks? Can I run them on Windows?

> Fonc/cola/coke can also turn out to be really fast - but that is a whole
> new platform, not really "Squeak".

True.

Cheers,
   - Andreas



More information about the Squeak-dev mailing list