Interesting result. But still, I feel that the computer should be able to do 
some inference. This could be at runtime, at compile time or during the 
development. I think than expecting the user to have the knowledge about how to 
parallelize an application is too much asking. 

I will read Charlotte's work.

Alexandre


On 29 Apr 2011, at 09:58, Toon Verwaest wrote:

> I have a hunch that Stefan is referring to the PhD thesis of Charlotte 
> Herzeel without giving names. As far as I understood from my discussions with 
> her (and her talks), it generally doesn't really pay off to automatically 
> parallelize on branches. You get minimal speedups (1% at best).
> 
> I tend to agree with Stefan / Michael / Guy Steele... Maybe you don't need 
> much, but the mapreduce style is the minimum requirement to give the language 
> enough "wiggle room" to automatically parallelize stuff. But it DOES require 
> you to restructure your application in a slightly more declarative fashion.
> 
> cheers,
> Toon
> 
> On 04/29/2011 04:55 PM, Alexandre Bergel wrote:
>> Hi Stefan,
>> 
>> I though about your email. I do not understand why automatic parallelization 
>> is not the way to go. In my opinion, the computer has much more knowledge 
>> about the programmer about where side effects appear and where to cut or 
>> split a computation.
>> 
>> Actually, if I want to be provocative, I would say that parallelization 
>> cannot be effective without being automatic. For a similar reason that the 
>> compiler will always know better than me how to properly allocate registers.
>> 
>> I feel it would be cheaper for me to buy a faster computer than to learn how 
>> to program in a multi-core fashion.
>> 
>> Cheers,
>> Alexandre
>> 
>> 
>>>> However, as I understand it, it's entirely up to user to write code
>>>> exploiting parallel Process explicitly right ?
>>> Sure, you have to do: n times: [ [ 1 expensiveComputation. ] fork ].
>>> 
>>> I don't belief in holy grails or silver bullets.
>>> Automatic parallelization is something nice for the kids, like Santa Clause 
>>> or the Easter Bunny...
>> 
>> 
> 
> 

-- 
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Alexandre Bergel  http://www.bergel.eu
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