[m-dev.] for review: direct reuse

[Ralph Becket]

>From Peter Ross on 21/09/2000 11:18:38
> On Thu, Sep 21, 2000 at 02:53:04AM -0700, Ralph Becket wrote:
> > 
> > which is certainly worse, except for the fact that, under the Mercury
> > scheme, having overwritten a larger cell with a smaller one, we no
longer
> > have the information that there is some extra space available if we
wanted
> > to go in the other direction.
> > 
> Good point, we may end up with a cascading stream of cell reuse, where
> we progressively use less and less of the cell.
> 
> It is something we should think about if there is a possible solution.

I'm not sure it's going to be that big a deal - just having sensible
structure reuse should make a real difference.  I suspect that carrying
around extra information (cell size) and complicating reuse (i.e. having
run-time tests to decide whether reuse is possible due to cell size)
would kill any gains made in the first place.

Instead, if one really wants to go for 100% reuse, one should design
one's data-structures a la the C version and accept that small cells
will waste some memory.  Otherwise, take reuse when you can and 
otherwise let the GC do its job.

Ralph

--
Ralph Becket      |      MSR Cambridge      |      rbeck at microsoft.com 

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