Well, I'm stumped. Two CPUs showing as four...

Post #79,849

2/6/03 12:02:58 PM

So I got the verrrry nice dual-1.8-Xeon webserver up and running. Completely. Migrated all the data, etc and it's actually in place and running now: web and accounting back-end. Basically IIS on Win2K.

After I finished everything and put it into production, I noticed something strange about it. Task Manager thinks it's got 4 CPUs, when it's really only got 2. Each "processor" shows different load graphs; no really, they're quite different. I've Googled my brains out (and even exhausted MSKB), and can't find anything relevant. FWIW, I'm using the standard ACPI Multiprocessor HAL.

Any ideas? criticisms? Why, how, and whether I should I fix it...or care.

Many fears are born of stupidity and ignorance -
Which you should be feeding with rumour and generalisation.
BOfH, 2002 "Episode" 10

Post #79,854

by SpiceWare

2/6/03 12:21:10 PM

Hyper-Threading

[link|http://www-106.ibm.com/developerworks/linux/library/l-htl/?ca=dgr-lnxw01HyperThread|Hyper-Threading speeds Linux]

The Intel Xeon processor introduces a new technology called Hyper-Threading (HT) that, to the operating system, makes a single processor behave like two logical processors. When enabled, the technology allows the processor to execute multiple threads simultaneously, in parallel within each processor, which can yield significant performance improvement. We set out to quantify just how much improvement you can expect to see.
...
The existence of Hyper-Threading support can be seen by using the command cat /proc/cpuinfo to show the presence of two processors, processor 0 and processor 1. Note the ht flag in Listing 1 for CPUs 0 and 1. In the case of no Hyper-Threading support, the data will be displayed for processor 0 only.

Darrell Spice, Jr.

[link|http://www.spiceware.org/|SpiceWare] - We don't do Windows, it's too much of a chore

Post #79,859

by tseliot

2/6/03 12:31:08 PM

Hey thanks! Ironic...

...I actually spoke to one of the Xeon et al designers about HT once while doing jury duty; knew all about it, but hadn't extended that knowledge to this problem! /snicker at myself

And remember, T Eliot spelled backwards is...

Many fears are born of stupidity and ignorance -
Which you should be feeding with rumour and generalisation.
BOfH, 2002 "Episode" 10

Post #79,868

by orion

2/6/03 12:42:24 PM

For a while there

I thought that maybe the CPUs were experiencing a Multiple Personality Disorder until I read the other post on this thread. :)

[link|http://pub75.ezboard.com/bantiiwethey|
New and improved, Chicken Delvits!]

Post #80,036

by pwhysall

2/7/03 2:18:32 AM

Be aware...

...that for software licencing purposes, that's four CPUs.

Oracle and Micorsoft see things this way, at least.

Post #90,092

by qstephens

3/21/03 2:37:03 PM

Re: Be aware...

Only on W2K. XP correctly recognises HT-enabled CPUs.

qts

Post #90,122

by folkert

3/21/03 3:41:43 PM

Talking SERVER here.

b4k4^2

[link|mailto:curley95@attbi.com|greg] - Grand-Master Artist in IT

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[link|http://www.eweek.com/article2/0,3959,857673,00.asp|Writing on wall, Microsoft to develop apps for Linux by 2004]

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Post #90,579

by qstephens

3/23/03 6:02:40 AM

Re: Well, I'm stumped. Two CPUs showing as four...

Talking SERVER here.

I'm aware of that. My comment still stands. Some people of my acquaintance have been hit by this.

qts

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