Linux and GC

Alaric B. Williams abw97@doc.ic.ac.uk
Tue, 12 May 1998 08:52:55 +0100


Scott L. Burson wrote:

> The technique Kragen suggests may have been studied, although I don't
> think I had heard of it, but it's not what's called a "write barrier".
>  A write barrier is a piece of code or possibly hardware that detects
> writes of pointers into memory having certain properties: roughly,
> where the cell into which the pointer is written will not be scanned
> (again) during the current collection, but the object to which the
> pointer points has not been marked as live.  A write barrier is needed
> in both fully incremental collectors, such as the Lisp machine's, as
> well as semi-incremental collectors (a term I just made up to cover
> collectors, such as Allegro's, that run uninterruptibly during a
> collection but scan and collect only a small amount of memory
> each time).

I'd still call it a write barrier, though, since it's extra checking
done on every write for the GC's benefit. It's just a funny kind of
write barrier.

> -- Scott

ABW

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Al Williams
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