[Haskell-cafe] Re: Suggested algorithm to control upper bound of space "leaks"

Shelby Moore shelby at coolpage.com
Sat Oct 31 17:53:57 EDT 2009

Shelby Moore wrote:
> One possible runtime optimization to provide an upper bound for cache
> control, might be to not cache thunks when the runtime computation time
> times number of cache hits, is less than the round-trip paging time
> multiplied by recent system paging load.
> Is this novel?  Is it useful?

Clarify and improve:

One possible idea for runtime optimization to provide a more deterministic
upper bound on paging load for cache control, might be to not cache
thunk-wise when for each thunk, the total tree of computation time under
the thunk multiplied by the number of cache hits on the thunk, is less
than the round-trip paging time of thunks under the tree multiplied by a
chosen factor of recent system paging load.  Or toggle the test on and off
on a chosen threshold of recent system paging load.

Obviously "heap size" could be substituted for "paging load", but my goal
is to make the optimization resolution independent, i.e. orthogonal to
system configuration such as RAM size, speed, virtual media size,
algorithm, etc..

The "catch-22" of the idea if any, probably derives from the permutations
of computation time from the lazy computation of thunks under the tree?

Note I realize this list is probably not the correct place to discuss
research.  I do not have time to do this research.  Any suggestion where I
could post or send this idea so people interested in this type of research
could see it?  Add a feature request to GHC bug tracker?  To the general
Haskell mailing list?

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