[coyotos-dev] sleep capability

[Jonathan S. Shapiro]

On Tue, 2007-01-23 at 10:53 -0500, Eric Northup wrote:
> Jonathan S. Shapiro wrote:
> [...]
> > Given (2), the only real solution is a deterministic scheduler. The
> > problem with this is that real users will not accept a 90%+ reduction in
> > effective computer speed.
> 
> Could you explain where this performance reduction comes from?  I agree
> that forcing computation to be deterministic will slow it down, but I
> didn't think it needed to be by that magnitude.

The 90% figure is made up, but here is the intuition.

You have some multithreaded thing that needs to run under a
deterministic schedule. You have a multiprocessor. Several of your
threads are eligible to run at any given time. Because of the
determinism, the scheduler cannot permit them to use a second CPU, and
cannot even permit them to use each other's slack time on the main CPU.

shap
-- 
Jonathan S. Shapiro, Ph.D.
Managing Director
The EROS Group, LLC
+1 443 927 1719 x5100