Bug 88774 - P4 with hyperthreading only indicates one CPU
Summary: P4 with hyperthreading only indicates one CPU
Alias: None
Product: Red Hat Linux
Classification: Retired
Component: kernel
Version: 9
Hardware: i686
OS: Linux
Target Milestone: ---
Assignee: Arjan van de Ven
QA Contact: Brian Brock
Depends On:
TreeView+ depends on / blocked
Reported: 2003-04-13 23:46 UTC by Dave Goldblatt
Modified: 2007-04-18 16:53 UTC (History)
0 users

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2004-09-30 15:40:47 UTC

Attachments (Terms of Use)
dmesg output on Asus P4G8X Deluxe w/BIOS revision 1004 (12.63 KB, text/plain)
2003-04-14 11:14 UTC, Dave Goldblatt
no flags Details
/proc/cpuinfo from P4G8X (453 bytes, text/plain)
2003-04-14 11:15 UTC, Dave Goldblatt
no flags Details
boot log from 2.5.68 detecting HT CPU correctly (12.70 KB, text/plain)
2003-04-26 19:43 UTC, Dave Goldblatt
no flags Details

Description Dave Goldblatt 2003-04-13 23:46:40 UTC
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4b) Gecko/20030411

Description of problem:
I know additional scheduler support for Intel's hyperthreading is in 2.5.x, but
I was under the impression that the later 2.4.x kernels would detect a
hyperthread-capable CPU as two logical processors; in my case I've got a P4
3.06GHz CPU on an Asus P4G8X which only appears as a single processor under
2.4.20-9smp, though the number of siblings in cpuinfo appears as 2.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
cat /proc/cpuinfo

Notice 2 siblings, yet only one CPU listed; I believe Xeons list two CPUs.    

Additional info:

Hyperthreading is enabled in the BIOS, and Windows XP detects two (logical) CPUs.

Comment 1 Arjan van de Ven 2003-04-14 08:45:37 UTC
this is most likely a bios bug; could you attach the full dmesg output, maybe
that will provide conclusive proof.

Comment 2 Dave Goldblatt 2003-04-14 11:14:35 UTC
Created attachment 91117 [details]
dmesg output on Asus P4G8X Deluxe w/BIOS revision 1004

Comment 3 Dave Goldblatt 2003-04-14 11:15:56 UTC
Created attachment 91118 [details]
/proc/cpuinfo from P4G8X

Just in case..

Comment 4 Arjan van de Ven 2003-04-14 11:17:15 UTC
please try adding acpismp=force to the kernel commandline and see if that helps

also note that systems with the nvidia binary only modules are unsupported.

Comment 5 Dave Goldblatt 2003-04-14 11:30:34 UTC
No luck with the acpismp option.  And yes, I know the non-nv driver isn't
supported; just happened to be trying it that boot - and I'm fairly certain it
doesn't affect the CPU identification code. ;-)

Comment 6 Dave Goldblatt 2003-04-26 19:43:49 UTC
Created attachment 91311 [details]
boot log from 2.5.68 detecting HT CPU correctly

Removed nvidia driver to be supported - same result.

Updated to beta BIOS (1005 beta 1) - same result.

Tried kernel 2.5.68 - both logical CPUs detected; boot log attached (used MADT)

Comment 7 Bugzilla owner 2004-09-30 15:40:47 UTC
Thanks for the bug report. However, Red Hat no longer maintains this version of
the product. Please upgrade to the latest version and open a new bug if the problem

The Fedora Legacy project (http://fedoralegacy.org/) maintains some older releases, 
and if you believe this bug is interesting to them, please report the problem in
the bug tracker at: http://bugzilla.fedora.us/

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