skaller wrote:
> On Tue, 2006-03-07 at 19:05 +0000, Asfand Yar Qazi wrote:
[--snip--]
> I point out that in fact, under the right conditions -- lots
> of processors and lots of variables -- it will probably provide better
> performance too. However this is hard to test -- not many
> of us have access to >2 cores on the same board. There certainly
> no way POSIX can deliver good performance: mutexes have to be
> synchronisation points and that requires ALL the CPUs to 
> flush their caches -- it doesn't scale. 

Interestingly, DragonflyBSD seems to be moving toward a slightly weaker
(relative to mutex) form of synchronisation which seems somewhat similar
to STMs:

   http://en.wikipedia.org/wiki/Serializing_tokens

I haven't look at it in detail, but it might be possible to use these to
implement STM in a mutex-free (cheap) way. (Though you might need some
level of hardware support unless you're content with page granularity
'exclusion').

Just thought I'd throw that in there. :)

Cheers,

-- 
Bardur Arantsson
<bardurREMOVE@THISimada.sdu.dk>
<bardurREMOVE@THISscientician.net>

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