Bug 166232 - wrong cpu speed displayed for Opteron on FC4_x86_64smp
wrong cpu speed displayed for Opteron on FC4_x86_64smp
Status: CLOSED NOTABUG
Product: Fedora
Classification: Fedora
Component: cpuspeed (Show other bugs)
4
x86_64 Linux
medium Severity medium
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Assigned To: Dave Jones
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Depends On:
Blocks:
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Reported: 2005-08-17 23:46 EDT by Peter Yim
Modified: 2015-01-04 17:21 EST (History)
2 users (show)

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Doc Type: Bug Fix
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Last Closed: 2005-08-18 03:43:13 EDT
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Description Peter Yim 2005-08-17 23:46:19 EDT
Description of problem:

- I am running FC4_x86_64smp on an IBM eServer model 326 with dual AMD opteron
250 cpu's (2.4GHz). However, when I invoke "/proc/cpuinfo", the system returns
my cpu speeds as being about 997 MHz (on both cpu's). 

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

- Linux version 2.6.12-1.1398_FC4smp (as well as earlier versions of FC4 too)

How reproducible:

- symptom is reproducible, consistently.

Steps to Reproduce:
1. "$ cat /proc/cpuinfo"
2.
3.
  
Actual results:

$ cat /proc/cpuinfo 

 processor       : 0
 vendor_id       : AuthenticAMD
 cpu family      : 15
 model           : 5
 model name      : AMD Opteron(tm) Processor 250
 stepping        : 10
 cpu MHz         : 996.910  <---------- (??? should be 2.4GHz) [2005.08.09: IBM
advised that this is a bug on FC4; processor speed is OK, just wrong speed disply]
 cache size      : 1024 KB
 fpu             : yes
 fpu_exception   : yes
 cpuid level     : 1
 wp              : yes
 flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext lm 3dnowext 3dnow
 bogomips        : 1986.56
 TLB size        : 1024 4K pages
 clflush size    : 64
 cache_alignment : 64
 address sizes   : 40 bits physical, 48 bits virtual
 power management: ts fid vid ttp    798

 processor       : 1
 vendor_id       : AuthenticAMD
 cpu family      : 15
 model           : 5
 model name      : AMD Opteron(tm) Processor 250
 stepping        : 10
 cpu MHz         : 996.910  <---------- (??? should be 2.4GHz)
 cache size      : 1024 KB
 fpu             : yes
 fpu_exception   : yes
 cpuid level     : 1
 wp              : yes
 flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext lm 3dnowext 3dnow
 bogomips        : 1986.56
 TLB size        : 1024 4K pages
 clflush size    : 64
 cache_alignment : 64
 address sizes   : 40 bits physical, 48 bits virtual
 power management: ts fid vid ttp

Expected results:

- both cpu's should show a speed of about 2400 MHz 

Additional info:

- have reported problem to IBM. They experimented, and were able to get the same
(erroneous) result when testing on FC4. However, they confirm that the correct
cpu speed is returned when the same is run with RHEL-AS 3.4 or RHEL-ES 3.5
Comment 1 Dave Jones 2005-08-18 03:43:13 EDT
if the machine is idle, the cpuspeed daemon will lower the speed to save power.
If you start some cpu intensive workload, it'll ramp back up.

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