Re: [PATCH RFC 3/9] RCU: Preemptible RCU

Paul E. McKenney
2007-10-01T22:25:04Z

On Mon, Oct 01, 2007 at 03:09:16PM -0700, Davide Libenzi wrote:
> On Mon, 1 Oct 2007, Paul E. McKenney wrote:
>
> > That would indeed be one approach that CPU designers could take to
> > avoid being careless or sadistic. ;-)
>
> That'd be the easier (unique maybe) approach too for them, from an silicon
> complexity POV. Distinguishing between different CPUs stores once inside a
> shared store buffer, would require tagging them in some way. That'd defeat
> most of the pros of having a shared store buffer ;)

Tagging requires but one bit per entry. Depends on the workload -- if
lots of barriers, bursty stores and little sharing, tagging might win.
If lots of sharing, then your suggested approach might win.

Thanx, Paul