LinuxQuestions.org
Latest LQ Deal: Latest LQ Deals
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Hardware
User Name
Password
Linux - Hardware This forum is for Hardware issues.
Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?

Notices


Reply
  Search this Thread
Old 11-25-2004, 05:31 PM   #1
General_Tso
Member
 
Registered: Jan 2003
Location: New York, NY, USA
Distribution: Mac OS X (10.4.6), Ubuntu 6.06
Posts: 183

Rep: Reputation: 30
P4 and Hyperthreading


Folks:

This may be obvious, but do all P4's have hyperthreading?

--Tso
 
Old 11-25-2004, 05:42 PM   #2
battousai9439
Member
 
Registered: Jul 2004
Distribution: Ubuntu 10.04
Posts: 32

Rep: Reputation: 15
I think so...
 
Old 11-25-2004, 06:10 PM   #3
slackMeUp
Member
 
Registered: Nov 2003
Distribution: Slack-where?
Posts: 654

Rep: Reputation: 30
no, not _all_ P4s have it. . .
 
Old 11-25-2004, 09:27 PM   #4
Electro
LQ Guru
 
Registered: Jan 2002
Posts: 6,042

Rep: Reputation: Disabled
Well yes and no. Yes they all have the wiring for hyperthreading but Intel picked certain models to activate the wiring at the factory. No you can not take a 2.0A GHz processor and activate hyperthreading. Also the motherboard have to support hyperthreading for the processor to take advantage of it. IMO, hyperthreading is a gimmick just to sell the processor and it is slower than using two physical processors.
 
Old 11-25-2004, 10:26 PM   #5
General_Tso
Member
 
Registered: Jan 2003
Location: New York, NY, USA
Distribution: Mac OS X (10.4.6), Ubuntu 6.06
Posts: 183

Original Poster
Rep: Reputation: 30
Is there some command, script, etc. a la cpuinfo that can tell you if hyperthreading is enabled? I'm just deciding what services I should have running...

Thanks for the input, folks!
 
Old 11-25-2004, 10:56 PM   #6
little confused
LQ Newbie
 
Registered: Nov 2004
Location: hi
Distribution: fedora
Posts: 6

Rep: Reputation: 0
On my dell 8300 p4 3.00 in bios under cpu hyperthreading is enabled or not.
 
Old 11-26-2004, 11:44 AM   #7
hkb33
Member
 
Registered: Sep 2004
Location: Raleigh NC
Distribution: Fedora / RHEL
Posts: 171

Rep: Reputation: 30
Check the BIOS on your system...if your CPU is hyperthread capable then you should be able to turn it on and off....if you don't have that option then your CPU probably isn't hyperthreaded. All systems that have Hyperthreaded CPU's need to have the ability to turn hyperthreading on and off in their BIOSes. Not all operating systems and softwares play nice with Hyperthreading.

If you have a CPU that is hyperthreaded you'll notice two things in Linux:

1) The operating system will see double the amont of installed CPU's and most likely install an smp kernel by default.

2) If you are booted to this smp kernel, then you will see two CPU's when running the following command:

cat /proc/cpuinfo

....and the earlier posters are correct....not all P4's are hyperthreaded. If you P4 system was built before late 2002, then it probably isn't HT capable.
 
Old 11-26-2004, 11:59 AM   #8
General_Tso
Member
 
Registered: Jan 2003
Location: New York, NY, USA
Distribution: Mac OS X (10.4.6), Ubuntu 6.06
Posts: 183

Original Poster
Rep: Reputation: 30
Thanks for all the info. Appreciate it.
 
Old 11-27-2004, 03:03 AM   #9
slackMeUp
Member
 
Registered: Nov 2003
Distribution: Slack-where?
Posts: 654

Rep: Reputation: 30
One thing to note...

Someone said that "all" P4s have the "wiring" for HTing. This is not entirely true. . . The first core used for the P4 (wallamite, but to hell with spelling) found in socket 423 and early 478 P4 systems did not have the "wiring" for HTing. It was the Northwood core that had the "wiring" and then in the core's mid life it was enabled on some chips. And by 'some' I mean, the more costly ones... hehe.
 
Old 11-27-2004, 01:01 PM   #10
Dutch3
Member
 
Registered: Feb 2002
Location: UK
Distribution: Mandriva
Posts: 179

Rep: Reputation: 31
....and although a HT cpu may not be as fast as two physical cpu's, it is still a substantial speed improvement and I'm very impressed with a P4 3Gig HT cpu on a Linux box.........

Dutch
 
Old 11-27-2004, 01:36 PM   #11
General_Tso
Member
 
Registered: Jan 2003
Location: New York, NY, USA
Distribution: Mac OS X (10.4.6), Ubuntu 6.06
Posts: 183

Original Poster
Rep: Reputation: 30
Quote:
Originally posted by Dutch3
....and although a HT cpu may not be as fast as two physical cpu's, it is still a substantial speed improvement and I'm very impressed with a P4 3Gig HT cpu on a Linux box.........

Dutch
Although I'm not a hardware junky, it seems like a good idea to me. Although people might make the case for it being a sales gimmick, it can be said that every new innovation is a gimmick to sell computers.
 
Old 11-27-2004, 01:50 PM   #12
whansard
Senior Member
 
Registered: Dec 2002
Location: Mosquitoville
Distribution: RH 6.2, Gen2, Knoppix,arch, bodhi, studio, suse, mint
Posts: 3,304

Rep: Reputation: 65
a friend of mine that works for intel benchmarks stuff like that, and sent me some of the results. some apps that support threading well can get up to close to a 2x speed improvement. i forgot what kind of stuff is helped the most, but some things are. a few things are slower.
 
Old 11-27-2004, 02:40 PM   #13
Dutch3
Member
 
Registered: Feb 2002
Location: UK
Distribution: Mandriva
Posts: 179

Rep: Reputation: 31
All I know is what took 10+ seconds on my previous P4 (such as parsing syslogs or refreshing rpm database package lists) now takes about 4 secs. Also KDE starts up in less than half the time.

If that's a gimmick, I'll have another!

D

Last edited by Dutch3; 11-27-2004 at 02:44 PM.
 
Old 11-27-2004, 05:39 PM   #14
J.W.
LQ Veteran
 
Registered: Mar 2003
Location: Boise, ID
Distribution: Mint
Posts: 6,642

Rep: Reputation: 87
Q: "Do all P4's have hyperthreading?"
A: No.

This Intel product spec sheet as well as this secondary article indicate which do and which don't. I've got an older P4 (2.4 B, purchased in Jan 2003) and it lacks HT. Oh well, hope this is of interest. -- J.W.

Last edited by J.W.; 11-27-2004 at 05:41 PM.
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
Getting hyperthreading working AMMullan Linux - Hardware 6 05-25-2004 05:35 PM
smp and hyperthreading? eelriver Slackware 3 05-13-2004 06:03 AM
Hyperthreading Igman Linux - General 2 12-21-2003 05:37 PM
hyperthreading gmi Linux - Laptop and Netbook 5 09-17-2003 02:28 AM
Hyperthreading jspaceman Linux - Hardware 6 07-05-2003 10:18 AM

LinuxQuestions.org > Forums > Linux Forums > Linux - Hardware

All times are GMT -5. The time now is 09:15 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration