On Tue, 9 Feb 1999, Ignatios Souvatzis wrote:

> On Tue, Feb 09, 1999 at 09:56:49AM -0800, Eduardo E. Horvath wrote:

> > When spinning on a lock the CPU doing the spinning needs to invalidate its
> > D$, and the CPU who grabs/releases the lock needs to force the store of
> > the lock through its D$ and store buffers to RAM.
> 
> Uhm, no. Real CPUs (I've read a lot of PPC documentation in the last year) have
> special primitives to build synchronization code... and were not, you could 
> always create a system call to deal with this.

Well SPARCs both have atomic instructions *and* need to use cache
synchronizing code.  And spinlocks are simply a special case of the
reader/writer problem.  If one CPU writes to a shared memory location,
this sort of synchronization is necessary to ensure other CPUs can see the
results without possible data corruption.

=========================================================================
Eduardo Horvath				eeh@one-o.com
	"I need to find a pithy new quote." -- me