[coyotos-dev] Explicit Persistence Considered Harmful

Jonathan S. Shapiro shap at eros-os.com
Fri Aug 22 12:51:12 CDT 2008


On Fri, 2008-08-22 at 13:30 -0400, Sandro Magi wrote:
> Jonathan S. Shapiro wrote:
> > On Fri, 2008-08-22 at 09:18 -0400, Sandro Magi wrote:
> >> Is that really a problem? The slower the GC operates, the higher the
> >> memory overhead (wasted space), but it will eventually complete.
> > 
> > The whole point of the PDP-1 design was NOT to run a background
> > mark-sweep pass. In the absence of such a mark-sweep pass, you can't
> > very easily defer the cycle management problem. In the *presence* of a
> > mark-sweep pass, you do not *need* to defer it.
> 
> I'm not sure how mark-sweep got into this. I was talking about a local 
> cycle collection as described by Bacon for reference counted systems. 
> Since the cycle collection may come across references to objects 
> on-disk, it would need to be done in the background in a modern system.

But on the PDP-1 there is no way to know that the cycle is local.



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