[webkit-dev] Is there a plan for supporting multi-process and WebCL in webkit

[Dirk Pranke]

Right, I get how ParallelArrays would work. I was asking Filip how you
might infer that an array could be a ParallelArray.

-- Dirk

On Wed, Apr 10, 2013 at 12:45 PM, Oliver Hunt <oliver at apple.com> wrote:

> The parallel arrays apis aren't a magic "make my code parallel" wand.
>
> They don't make general code parallel, they simply provide a bunch of
> functions like map, etc where if you restrict your list of language
> features to a specific subset, they'll vectorise it.
>
> For instance
>
> ParallelArray([1,2,3]).map(function(a,v) { return v * 2; })
>
> would be vectorised
>
> ParallelArray([1,2,3]).map(function(a,v) { return v.x * 2; })
>
> wouldn't be.
>
> This isn't "solve autovectorisation", this is "we've been given a specific
> operation to perform on each element of an array, parallelise it if
> possible", and what's possible is arbitrarily limited, and require a
> distinct type that isn't an array.
>
> --Oliver
>
> On Apr 10, 2013, at 12:37 PM, Dirk Pranke <dpranke at chromium.org> wrote:
>
>
>
>
> On Wed, Apr 10, 2013 at 7:37 AM, Filip Pizlo <fpizlo at apple.com> wrote:
>
>>
>>
>> On Apr 10, 2013, at 2:29 AM, "Pozdnyakov, Mikhail" <
>> mikhail.pozdnyakov at intel.com> wrote:
>>
>> >
>> >
>> >> Why not infer ParallelArrays automatically?
>> > Sorry, did not get it. Could you please elaborate?
>>
>> Normal JS arrays. You use them with pure computation. Profiler notices
>> this. And then the same things that you have in the ParallelArrays proposal
>> now work except you don't need a new type.
>>
>>
> Compiler writers have been chasing this problem for 50 years, with (AFAIK)
> very limited success for languages that don't give you compile-time
> annotations to help you along. I'm not aware of any work on JIT compilers
> doing this. Why do you think we could do better? (Honest question, I'm not
> trying to be snarky, nor am I an expert).
>
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>
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