[Vm-dev] RoarVM: The Manycore SqueakVM

[Stefan Marr]

Hi Bert:

On 04 Nov 2010, at 21:49, Bert Freudenberg wrote:

>>>> Then, the current implementation based on pthreads is quite a bit slower then our version which uses plain Unix processes.
> 
> Wait. What do you mean by "current version" vs. "our version"?
Just imprecise wording, mixed with my wish to actually experiment with that issue.
On the Tilera we are using the process model with Tilera specific libraries.
On x86 systems, we are using threads. However, that makes things quite a bit slower, and when I find the time, I will implement the necessary cross-process shared-memory libraries to get rid of the threads and use processes like on Tilera.


>>>> The GC is really not state of the art.
>>>> And all that adds up rather quickly I suppose...
>>> 
>>> Hmm, that doesn't sound like it should make it 4x slower ...
>> Do you know some numbers for the switch/case-based vs. the threaded version on the standard VM?
>> How much do you typically gain by it? 
> 
> I don't really remember but it was well below 50%, more like 10%-20% I think.
Hm, ok, that doesn't sound like something I want to spend time on then.



>> One thing I forgot to mentioned in this context, it the object table we use.
>> That is also something which is not exactly making the VM faster.
> 
> Ah, yes. That could make quite a difference. You wouldn't be calling a function for each object access though I hope?
Well, depends on what the compiler is doing with our code.
It is supposed to inline, and there are no virtual calls...

Best regards
Stefan


-- 
Stefan Marr
Software Languages Lab
Vrije Universiteit Brussel
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http://soft.vub.ac.be/~smarr
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