Re: More than 8 CPUs detected and CONFIG_X86_PC cannot handle it on 2.6.16-rc6

[Krzysztof Oledzki <olel@ans.pl>]

On Wed, 15 Mar 2006, Chuck Ebbert wrote:

> In-Reply-To: <Pine.LNX.4.64.0603120256480.14567@bizon.gios.gov.pl>
>
> On Sun, 12 Mar 2006 03:04:40 +0100, Krzysztof Oledzki wrote:
>
> > After upgrading to 2.6.16-rc6 I noticed this strange message:
> >
> > More than 8 CPUs detected and CONFIG_X86_PC cannot handle it.
> > Use CONFIG_X86_GENERICARCH or CONFIG_X86_BIGSMP.
> >
> > This is a Dell PowerEdge SC1425 with two P4 Xeons with HT enabled (so with
> > totoal of 4 logical CPUs).
>
> In a later message, you wrote:
>
> > ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled)
> > Processor #0 15:4 APIC version 20
> > ACPI: LAPIC (acpi_id[0x02] lapic_id[0x06] enabled)
> > Processor #6 15:4 APIC version 20
>             ^
> > ACPI: LAPIC (acpi_id[0x03] lapic_id[0x01] enabled)
> > Processor #1 15:4 APIC version 20
> > ACPI: LAPIC (acpi_id[0x04] lapic_id[0x07] enabled)
> > Processor #7 15:4 APIC version 20
>             ^
>
> What processor numbers did you get on 2.6.15.x?

Mar  6 00:08:03 fw2 kernel: Processor #0 15:4 APIC version 20
Mar  6 00:08:03 fw2 kernel: Processor #6 15:4 APIC version 20
Mar  6 00:08:03 fw2 kernel: Processor #1 15:4 APIC version 20
Mar  6 00:08:03 fw2 kernel: Processor #7 15:4 APIC version 20


> Does /proc/cpuinfo show all four CPUs?
Yes.

# cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.20GHz
stepping        : 3
cpu MHz         : 3200.000
cache size      : 2048 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 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni monitor ds_cpl cid cx16 xtpr
bogomips        : 6404.87

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.20GHz
stepping        : 3
cpu MHz         : 3200.000
cache size      : 2048 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 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni monitor ds_cpl cid cx16 xtpr
bogomips        : 6400.28

processor       : 2
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.20GHz
stepping        : 3
cpu MHz         : 2800.000
cache size      : 2048 KB
physical id     : 3
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 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni monitor ds_cpl cid cx16 xtpr
bogomips        : 6400.31

processor       : 3
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.20GHz
stepping        : 3
cpu MHz         : 2800.000
cache size      : 2048 KB
physical id     : 3
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 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni monitor ds_cpl cid cx16 xtpr
bogomips        : 6400.32


> If you start four CPU-hungry processes, do all four show 100% utilization in top(1)?

# cd /usr/src/linux
# /usr/bin/time make -j10 
(...)

Cpu0  : 94.4% us,  5.3% sy,  0.0% ni,  0.3% id,  0.0% wa,  0.0% hi,  0.0% si
Cpu1  : 92.4% us,  5.3% sy,  0.0% ni,  2.3% id,  0.0% wa,  0.0% hi,  0.0% si
Cpu2  : 91.7% us,  6.6% sy,  0.0% ni,  0.3% id,  1.3% wa,  0.0% hi,  0.0% si
Cpu3  : 94.7% us,  5.3% sy,  0.0% ni,  0.0% id,  0.0% wa,  0.0% hi,  0.0% si


Best regards,

				Krzysztof Olędzki