Re: CVS commit: src/sys

[David Laight <david%l8s.co.uk@localhost>]

On Sat, Jul 30, 2011 at 11:04:24PM +0200, Joerg Sonnenberger wrote:
... 
> Note that for a uncontested resource, the overhead of a mutex for a
> single operation tends to be comparable, if store fences have a similar
> price than bus locked operation on an owned cache line.

I remember being told that you couldn't avoid a lock, and algorithms
that claimed to do so were broken.
The so-called atomic ops effectively use the data item itself
as the lock.
For a single access this might be a gain because 'unlock' often
needs another synchronising bus cycle.

        David

-- 
David Laight: david%l8s.co.uk@localhost