Subject: Re: NetBSD SMP support
To: Geert Hendrickx <>
From: Manuel Bouyer <>
List: netbsd-users
Date: 11/09/2006 12:05:14
On Thu, Nov 09, 2006 at 10:20:52AM +0100, Geert Hendrickx wrote:
> On Wed, Nov 08, 2006 at 11:13:39PM +0100, Manuel Bouyer wrote:
> > Works fine here on dual-Xeon mail hubs (because of hyperthreading the system
> > sees 4 CPUs). The system runs mimedefang, which calls spamassassin and
> > clamav for each mail forwarded, so it has quite a bit of work to do.
> How well does NetBSD work with HT-SMP machines, is it able to distinct virtual
> CPU's from physical CPU's?  e.g. if there are two heavy threads, is there a
> chance they will be scheduled on two virtual CPU's on the same physical CPU,
> or will they always be split maximally across physical CPU's?

No currently it doesn't make a difference between virtual and physical.
It should not matter much as long as you have more runnable processes than
virtual CPUs (I tested this with a make -jx, there's a small benefit having
HT enbaled on a SMP machine)
If there are less runable processes than CPUs the scheduling may not be

Manuel Bouyer, LIP6, Universite Paris VI. 
     NetBSD: 26 ans d'experience feront toujours la difference