[Haskell-cafe] Automatic parallelism in Haskell,
similar to "make -j4"?
dons at galois.com
Sun Nov 2 19:48:39 EST 2008
> On Sun, Nov 2, 2008 at 6:44 PM, Bulat Ziganshin
> <bulat.ziganshin at gmail.com> wrote:
> >> What would it take to implement a -j equivalent for, say, GHC? Or if
> >> this is not possible, what is wrong with my reasoning?
> > problem is that make have rather large pices of work which it can run
> > parallel. if ghc will try to parallel every machine operation, it will
> > pend more time maintaining these jobs. 'par' is just the way to tell
> > GHC "this part of job is large enough"
> Right, but couldn't the Haskell complier+runtime discover "rather
> large pieces of work"?
Requires runtime profiling to work out the costs.
See this paper which implements this this idea,
Note that for subsets of Haskell, where we have more information
statically about the costs involves, we can do the parallelism
automatically. Data Parallel Haskell is the prime example.
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