Subject: Re: Hyperthreading?
To: Simon Burge <simonb@wasabisystems.com>
From: Frederick Bruckman <fredb@immanent.net>
List: port-i386
Date: 09/20/2003 13:55:31
On Sun, 21 Sep 2003, Simon Burge wrote:

> On Thu, Sep 18, 2003 at 03:24:31AM -0500, Peter Seebach wrote:
>
> > I know that, on some systems, a P4 with hyperthreading looks like two
> > processors.  Should this be working on NetBSD-current?  Is it useful?
> > I know it works in BSD/OS, and I also hear that the net performance gain
> > is typically negative.  :)
>
> Here's some tests I ran on a dual 2.8GHz Xeon around the end of June,
> using "./build.sh release":

> Right now that box is running with HT disabled, since I figured the
> "extra" CPUs weren't worth it.

I bet where it would really help, if it helps at all, is when you have
a single process taking up at least half of the available CPU, as when
you're transcoding video, or perhaps when two processes are together
taking up most of the CPU, in either case so that there's a high
probability that the switch will take you back to the process that
just ran.

Frederick