Subj : Re: questions re: atomic<>
To   : comp.programming.threads
From : Sean Kelly
Date : Fri Jun 24 2005 02:39 pm

Alexander Terekhov wrote:
> Sean Kelly wrote:
> [...]
> > will be refreshed, etc.  This all seemed to make sense until the more
> > recent addition of msync::slfence, as I can't envision an algorithm
>
> Hazard pointers, for example.

Oops.  Okay, this makes sense now.

> > with itself).  I can only conclude that this particular mechanism means
> > "wait for pending writes from ALL processors to complete before
> > beginning the following reads," so I'm wondering about my original
>
> No. Only local pending writes.

So then LOCK exists as one of the few instructions that forces a bus
lock, and this is actually to allow atomic CAS--the mfence aspect is
just a side effect.  This all makes a lot more sense now.  Thanks!


Sean

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