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Asked: 2011-06-05 03:05:51 +0800 CST

Processors with the same id,why?

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Here's the output of cat /proc/cpuinfo:

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 2
model name  : Quad-Core AMD Opteron(tm) Processor 2350 HE
stepping    : 3
cpu MHz     : 1994.998
cache size  : 512 KB
physical id : 0
siblings    : 1
core id     : 0
cpu cores   : 1
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu de tsc msr pae cx8 apic cmov pat clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch
bogomips    : 4000.86
TLB size    : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 2
model name  : Quad-Core AMD Opteron(tm) Processor 2350 HE
stepping    : 3
cpu MHz     : 1994.998
cache size  : 512 KB
physical id : 0
siblings    : 1
core id     : 1
cpu cores   : 1
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu de tsc msr pae cx8 apic cmov pat clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch
bogomips    : 4000.86
TLB size    : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 2
model name  : Quad-Core AMD Opteron(tm) Processor 2350 HE
stepping    : 3
cpu MHz     : 1994.998
cache size  : 512 KB
physical id : 0
siblings    : 1
core id     : 1
cpu cores   : 1
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu de tsc msr pae cx8 apic cmov pat clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch
bogomips    : 4000.86
TLB size    : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 2
model name  : Quad-Core AMD Opteron(tm) Processor 2350 HE
stepping    : 3
cpu MHz     : 1994.998
cache size  : 512 KB
physical id : 0
siblings    : 1
core id     : 1
cpu cores   : 1
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu de tsc msr pae cx8 apic cmov pat clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt lm 3dnowext 3dnow constant_tsc rep_good pni cx16 popcnt lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch
bogomips    : 4000.86
TLB size    : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate

Why 4 processors are all with the id 0 (processor : 0)?

central-processing-unit

1 Answers

  1. Best Answer

    Your kernel may be configured without SMP support. See the source for proc.c:

            unsigned int cpu = 0;
...
#ifdef CONFIG_SMP
        cpu = c->cpu_index;
#endif

    This cpu variable is then used in the output of the processor field in /proc/cpuinfo.

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