Re: Whats' the proper senario of par-map? (Was Re: bug#13188: par-map causes VM stack overflow)

[Andy Wingo]

On Fri 29 Mar 2013 06:49, Mark H Weaver <address@hidden> writes:

>> scheme@(guile-user)> ,time (define a (map (lambda (x) (expt x 5)) (iota
>> 10000)))
>> ;; 0.008019s real time, 0.007979s run time.  0.000000s spent in GC.
>> scheme@(guile-user)> ,time (define a (par-map (lambda (x) (expt x 5))
>> (iota 10000)))
>> ;; 6.596471s real time, 6.579375s run time.  1.513880s spent in GC.
>
> The timings above suggest that, on your machine, the overhead of
> 'par-map' is in the neighborhood of 660 microseconds per thread (that's
> the total run time divided by 10000 iterations).

Per item, you mean?  Anyway this seems like a really high overhead, and
we shouldn't make too many excuses for it ;)

Andy
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