what's the point of rpython?

Paul Rubin http
Wed Jan 21 03:29:01 CET 2009


"Rhodri James" <rhodri at wildebst.demon.co.uk> writes:
> > What cpu's do you know of that can atomically increment and decrement
> > integers without locking?
> 
> x86 (and pretty much any 8080 derivative, come to think of it).

It would not have occurred to me that "lock inc" increments "without
locking".  I understand that's different from a lock value sitting in
the data object but I thought that "lock-free algorithm" meant one
that didn't assert any of these hardware locks either.  Maybe I'm
wrong.

> Just do the locking properly and worry about optimisations later.

That has already been tried, and found to be unacceptably slow for the
purpose at hand.  Now we're looking for the optimizations.



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