Simon Marlow simonmar at microsoft.com
Mon May 17 16:11:49 EDT 2004

On 17 May 2004 14:53, Christian Maeder wrote:

> Today there's additionally running a fat (600MB) vmware on davinci.
> I thought page faults somehow correlate with memory consumption. Have
> you a better idea to measure time and space?

Page faults, assuming you got the information from time(1) are pretty
useless.  For memory consumption you can measure two things: total
allocation, which is gotten from '+RTS -sstderr -RTS', and live data,
which is gotten from a heap profile.  Beware laziness effects when
making measurements: try to ensure that both examples are evaluating
exactly the "same" things.

By the way, can we see the code for your tests?  What mix of operations
are you measuring?  What is the Map+IntMap version of your test

>> You can play the {-# UNPACK #-} trick in the IntMap code too, BTW.
> -- | A map of integers to values @a at .
> data IntMap a = Nil
>                | Tip !Key a
>                | Bin !Prefix !Mask !(IntMap a) !(IntMap a)
> On Prefix and Mask?


> When I omitted the "!" in " !k a !(Map k a) !(Map k a)"
> time was faster but page faults increased:
> Map-only:   7.37    29767

You should measure this version, because it is closer to what FiniteMap
does (plus there seems to be no good reason to force strictness on the
elements in a general purpose Map type).


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