Subject: Re: scheduler woes on MPACPI kernel
To: None <>
From: Manuel Bouyer <>
List: current-users
Date: 01/18/2005 22:46:21
On Tue, Jan 18, 2005 at 08:25:51PM +0000, wrote:
> Manuel Bouyer wrote:
> >On Tue, Jan 18, 2005 at 05:09:48PM +0200, Teemu Rinta-aho wrote:
> >
> >>Does anyone know if there has been any analysis on the
> >>effect of P4 hyperthreading and MP support of NetBSD,
> >>compared to a UP kernel?
> >
> >
> >I tested with a make -j4 kernel build. A few % improvements with a MP 
> >kernel.
> >But this is because we have a big kernel lock I think. On linux 2.6, which
> >has finer-grained locking, a MP kernel increased the build time instead of
> >decreasing it.
> >
> So there is no point in having MP system if it actually increases total 
> time :-)
> Somebody did a benchmark recently of NetBSD vs FreeBSD and NetBSD came 
> on top. So people said if it was done on a MP system, FreeBSD would be 
> faster, due to finer-grained locking, etc. Any ideas if that's true?

Note that we were talking about a single hyperthreaded processor. The
result would probably have been different on a real dual-CPU system.

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference