Re: Athlon 64 X2 cpuinfo oddities

From: Rafael J. Wysocki
Date: Mon Jan 09 2006 - 16:06:45 EST


Hi,

On Monday, 9 January 2006 21:18, Jesper Juhl wrote:
> I recently bought a Dual Core AMD Athlon 64 X2 4400+ CPU and dropped a
> 2.6.15 kernel on the box and it runs very nice, but /proc/cpuinfo
> shows a few things that seem slightly odd to me (haven't tried earlier
> kernels on this so I don't know if cpuinfo looked different
> previously).
> It may be that it's absolutely correct and not odd at all, but I
> thought I'd just ask :)
>
> Here's what cat /proc/cpuinfo shows :
>
> juhl@dragon:~$ cat /proc/cpuinfo
> processor : 0
> vendor_id : AuthenticAMD
> cpu family : 15
> model : 35
> model name : AMD Athlon(tm) 64 X2 Dual Core Processor 4400+
> stepping : 2
> cpu MHz : 2200.260
> cache size : 1024 KB
> physical id : 0
> siblings : 1
> 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 : 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 ht syscall nx mmxext
> fxsr_opt lm 3dnowext 3dnow pni lahf_lm cmp_legacy
> bogomips : 4403.36
>
> processor : 1
> vendor_id : AuthenticAMD
> cpu family : 15
> model : 35
> model name : AMD Athlon(tm) 64 X2 Dual Core Processor 4400+
> stepping : 2
> cpu MHz : 2200.260
> cache size : 1024 KB
> physical id : 127
> siblings : 1
> core id : 1
> cpu cores : 1
> fdiv_bug : no
> hlt_bug : no
> f00f_bug : no
> coma_bug : no
> 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 ht syscall nx mmxext
> fxsr_opt lm 3dnowext 3dnow pni lahf_lm cmp_legacy
> bogomips : 4399.53
>
>
> So, what's odd with that?
>
> Well, first of all you'll notice that the second core shows a
> "physical id" of 127 while the first core shows an id of 0. Shouldn't
> the second core be id 1, just like the "core id" fields are 0 & 1?

FWIW, I'm running 2.6.15 on Athlon X2 4200 and the second core's
physical id is 0 (ie. same as of the frist one), the number of siblings
for each core is 2, and the "cpu cores" value is 2 as well (yours is 1,
apparently ;-)).

Greetings,
Rafael
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