[clug-talk] Hyper-Threading core count?

[Mark Carlson]

> On 10/4/05, Roy Souther <roy at silicontao.com> wrote:
> Anyone running Intel Xeon's with Hyper-Threading? Does each CPU show up as a dual core?
> I was doing some admin on a system last month and it had two CPU's with two cores each.  Or at least that is what Linux showed in top and proc.
> I did not look closely at the CPU info. I want to get a spec on building a quad core system like that and can only find dual Intel motherboards that use Xeon CPU's not the Intel Pentium D's.
>
> Is anyone running a Xeon with HT? How well does it perform? What would CLUG'ers recommend.
>
> I am building an LTSP server to host about 50 KDE desktops with OpenOffice running all the time. I want quad core and 4GB RAM.

My experience with LTSP has been on a dual P4 Xeon 3.2GHz box with HT.
 At most there were 34 (? all of the computers in DeVry's room 116
anyways) machines connected most of the time, and not usually any
more.  It performed quite well over the 100Mb connection.  If I'm not
mistaken it was on a PowerEdge server, and AFAIK, the HTs do show up
as 2 CPUs to Linux (it showed 4 CPUs.)

Recently, however, I was running GIMPS on my P4 HT laptop, and it
would lock up the system in under 30 minutes.  After disabling HT in
the BIOS and recompiling my kernel to not support SMP, it's been
running fine for a couple days.  I found out at PROGSIG in September
that this could be a result of "cache juggling" (I don't remember how
that was said exactly) and may be a known issue with heavily loaded HT
processors.

Personally, I am an AMD fan, so I would agree with Michael Lauzon and
look into getting a 2-way dual core Opteron setup.

-Mark Carlson