Bug 173999 - 4CPU's register in 2 CPU system
4CPU's register in 2 CPU system
Status: CLOSED NOTABUG
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel (Show other bugs)
4.0
i686 Linux
medium Severity medium
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Assigned To: Kernel Maintainer List
Brian Brock
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Depends On:
Blocks:
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Reported: 2005-11-23 10:18 EST by Nayan Kapadia
Modified: 2007-11-30 17:07 EST (History)
0 users

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Environment:
Last Closed: 2005-11-23 16:31:10 EST
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Regression: ---
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
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Description Nayan Kapadia 2005-11-23 10:18:57 EST
Description of problem:
Using RHELAS4 with 2.6.9-5 kernel and saw that 4 cpu's were being seen 
in /proc/cpuinfo aswell as dmesg but only 2 are physically present.  Upgraded 
kernel to 2.6.9-22.0.1 and the problem still exist. No preformance or 
usability issues have resulted thus far, but we have not really stressed the 
server.

We are using HP DL380, which is only capable of 2 CPU's and 2 CPU's are 
installed only.

Version-Release number of selected component (if applicable):
kernel-smp-2.6.9-22.0.1.EL

How reproducible:


Steps to Reproduce:
1.Install RHEL4AS on HP DL380 with 2 cpu's
2.Observe dmesg and /proc/cpuinfo for number of processors

    
Actual results:
4 CPU's are seen by the operating system

Expected results:
2 CPU's should be seen as 2 only are installed.

Additional info:
excerpt from dmesg:

Initializing CPU#0
CPU 0 irqstacks, hard=c03e7000 soft=c03c7000
PID hash table entries: 4096 (order: 12, 65536 bytes)
Detected 3201.622 MHz processor.
Using tsc for high-res timesource
Console: colour VGA+ 80x25
Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
Memory: 4084732k/4653052k available (1863k kernel code, 43036k reserved, 753k 
data, 176k init, 3211208k highmem)
Calibrating delay loop... 6307.84 BogoMIPS (lpj=3153920)
Security Scaffold v1.0.0 initialized
SELinux:  Initializing.
SELinux:  Starting in permissive mode
There is already a security framework initialized, register_security failed.
selinux_register_security:  Registering secondary module capability
Capability LSM initialized as secondary
Mount-cache hash table entries: 512 (order: 0, 4096 bytes)
CPU: After generic identify, caps: bfebfbff 20000000 00000000 00000000
CPU: After vendor identify, caps:  bfebfbff 20000000 00000000 00000000
monitor/mwait feature present.
using mwait in idle threads.
CPU: Trace cache: 12K uops, L1 D cache: 16K
CPU: L2 cache: 1024K
CPU0: Initial APIC ID: 0, Physical Processor ID: 0
CPU: After all inits, caps:        bfebf3ff 20000000 00000000 00000080
Intel machine check architecture supported.
Intel machine check reporting enabled on CPU#0.
CPU0: Intel P4/Xeon Extended MCE MSRs (24) available
CPU0: Thermal monitoring enabled
Enabling fast FPU save and restore... done.
Enabling unmasked SIMD FPU exception support... done.
Checking 'hlt' instruction... OK.
CPU0: Intel(R) Xeon(TM) CPU 3.20GHz stepping 01
per-CPU timeslice cutoff: 2925.73 usecs.
task migration cache decay timeout: 3 msecs.
Booting processor 1/1 eip 3000
CPU 1 irqstacks, hard=c03e8000 soft=c03c8000
Initializing CPU#1
Calibrating delay loop... 6389.76 BogoMIPS (lpj=3194880)
CPU: After generic identify, caps: bfebfbff 20000000 00000000 00000000
CPU: After vendor identify, caps:  bfebfbff 20000000 00000000 00000000
monitor/mwait feature present.
CPU: Trace cache: 12K uops, L1 D cache: 16K
CPU: L2 cache: 1024K
CPU1: Initial APIC ID: 1, Physical Processor ID: 0
CPU: After all inits, caps:        bfebf3ff 20000000 00000000 00000080
Intel machine check architecture supported.
Intel machine check reporting enabled on CPU#1.
CPU1: Intel P4/Xeon Extended MCE MSRs (24) available
CPU1: Thermal monitoring enabled
CPU1: Intel(R) Xeon(TM) CPU 3.20GHz stepping 01
Booting processor 2/6 eip 3000
CPU 2 irqstacks, hard=c03e9000 soft=c03c9000
Initializing CPU#2
Calibrating delay loop... 6389.76 BogoMIPS (lpj=3194880)
CPU: After generic identify, caps: bfebfbff 20000000 00000000 00000000
CPU: After vendor identify, caps:  bfebfbff 20000000 00000000 00000000
monitor/mwait feature present.
CPU: Trace cache: 12K uops, L1 D cache: 16K
CPU: L2 cache: 1024K
CPU2: Initial APIC ID: 6, Physical Processor ID: 3
CPU: After all inits, caps:        bfebf3ff 20000000 00000000 00000080
Intel machine check architecture supported.
Intel machine check reporting enabled on CPU#2.
CPU2: Intel P4/Xeon Extended MCE MSRs (24) available
CPU2: Thermal monitoring enabled
CPU2: Intel(R) Xeon(TM) CPU 3.20GHz stepping 01
Booting processor 3/7 eip 3000
CPU 3 irqstacks, hard=c03ea000 soft=c03ca000
Initializing CPU#3
Calibrating delay loop... 6389.76 BogoMIPS (lpj=3194880)
CPU: After generic identify, caps: bfebfbff 20000000 00000000 00000000
CPU: After vendor identify, caps:  bfebfbff 20000000 00000000 00000000
monitor/mwait feature present.
CPU: Trace cache: 12K uops, L1 D cache: 16K
CPU: L2 cache: 1024K
CPU3: Initial APIC ID: 7, Physical Processor ID: 3
CPU: After all inits, caps:        bfebf3ff 20000000 00000000 00000080
Intel machine check architecture supported.
Intel machine check reporting enabled on CPU#3.
CPU3: Intel P4/Xeon Extended MCE MSRs (24) available
CPU3: Thermal monitoring enabled
CPU3: Intel(R) Xeon(TM) CPU 3.20GHz stepping 01
Total of 4 processors activated (25477.12 BogoMIPS).
ENABLING IO-APIC IRQs
..TIMER: vector=0x31 pin1=2 pin2=-1
checking TSC synchronization across 4 CPUs: passed.
Brought up 4 CPUs

/proc/cpuinfo contents:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.20GHz
stepping        : 1
cpu MHz         : 3201.622
cache size      : 1024 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov 
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe lm pni monitor 
ds_cpl cid xtpr
bogomips        : 6307.84

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.20GHz
stepping        : 1
cpu MHz         : 3201.622
cache size      : 1024 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov 
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe lm pni monitor 
ds_cpl cid xtpr
bogomips        : 6389.76

processor       : 2
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.20GHz
stepping        : 1
cpu MHz         : 3201.622
cache size      : 1024 KB
physical id     : 3
siblings        : 2
core id         : 3
cpu cores       : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov 
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe lm pni monitor 
ds_cpl cid xtpr
bogomips        : 6389.76

processor       : 3
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.20GHz
stepping        : 1
cpu MHz         : 3201.622
cache size      : 1024 KB
physical id     : 3
siblings        : 2
core id         : 3
cpu cores       : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov 
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe lm pni monitor 
ds_cpl cid xtpr
bogomips        : 6389.76
Comment 1 Bill Rugolsky, Jr. 2005-11-23 10:43:40 EST
NOTABUG. You have hyperthreading enabled on the processors, as you can see from
the /proc/cpuinfo: look at "physical id" and "siblings".  Turn off
hyperthreading in the BIOS, or add "noht" to the kernel commandline.
Comment 2 Jason Baron 2005-11-23 16:31:10 EST
indeed. the 'noht' command line is not available yet for RHEL4, but it should be
implemented in U3. thanks.

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