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Date: Tue, 20 Apr 2004 01:13:34 -0700
From: Kris Kennaway <kris@obsecurity.org>
To: Rumen Telbizov <altares@e-card.bg>
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cc: Kris Kennaway <kris@obsecurity.org>
Subject: Re: HTT and SMP question
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On Tue, Apr 20, 2004 at 10:38:37AM +0300, Rumen Telbizov wrote:
> Hello,=20
>=20
> On Mon, Apr 19, 2004 at 02:35:23AM -0700, Kris Kennaway wrote:
> > On Mon, Apr 19, 2004 at 11:20:52AM +0200, Morten A. Middelthon wrote:
> > > sysctl -w machdep.hlt_logical_cpus=3D0
> > >=20
> > > that did the trick. I added it to loader.conf as well.
> > >=20
> > > regards,
> >=20
> > Note that HTT causes worse performance in many workloads, which is why
> > that sysctl defaults to off.
>=20
> Would you please point out some cases when HTT with machdep.hlt_logical_c=
pus=3D0
> causes worse performance than machdep.hlt_logical_cpus=3D1?
> I am using an HTT Xeon since recently and in my tests it showed that
> machdep.hlt_logical_cpus=3D0 is better!
> A simple ubench (spawning 2 processes) gives better results in 0 mode!

My parallel package builds are slower on build machines with HTT.
It's not a magic bullet.

Kris

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