Red Hat Bugzilla – Bug 88774
P4 with hyperthreading only indicates one CPU
Last modified: 2007-04-18 12:53:01 EDT
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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):
Steps to Reproduce:
Notice 2 siblings, yet only one CPU listed; I believe Xeons list two CPUs.
Hyperthreading is enabled in the BIOS, and Windows XP detects two (logical) CPUs.
this is most likely a bios bug; could you attach the full dmesg output, maybe
that will provide conclusive proof.
Created attachment 91117 [details]
dmesg output on Asus P4G8X Deluxe w/BIOS revision 1004
Created attachment 91118 [details]
/proc/cpuinfo from P4G8X
Just in case..
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.
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. ;-)
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)
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/