[Haskell] Pugs gains SMP parallelism support.

Taral taralx at gmail.com
Mon Oct 23 13:27:15 EDT 2006

On 10/23/06, Sebastian Sylvan <sylvan at student.chalmers.se> wrote:
> I'm not so sure that a newArray is faster than N copies of
> newEmptyMVar, at any rate the [MVar] approach has *no* congestion
> points

They are congestion points because each thread could conceivably
attempt to putMVar at the same time as the main thread tries to

> You could try having an array of MVars to get rid of the extra space
> that the list takes, and use unsafeWrite etc. to get faster writes
> back to the result array. Then do takeMVar on each item in the array
> to get "block for N resources" behaviour without having a single
> resource semaphore that could (profile!) suffer from congestion.

Meh, it seems like a lot of work for little.

How many elements were in the benchmark list? I notice that the
original benchmark ran for 5 seconds or so, what happens if the work
per element is increased? If the length is increased? It's possible
that the array approach wins when you try to process 100,000 elements.

Taral <taralx at gmail.com>
"You can't prove anything."
    -- Gödel's Incompetence Theorem

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