Dual core AMD64 4400+ X2 works fine on Abit AV8

[Alexander Konovalenko]

On Wednesday 21 September 2005 17.37, Attila Nagy wrote:
> Alexander Konovalenko wrote:
> > 2) recompiled and installed 5.4-STABLE kernel with "options SMP", then I
> > tested it with old single core CPU
> > CPU: AMD Athlon(tm) 64 X2 Dual Core Processor 4400+ (2247.42-MHz K8-class
> > CPU) Origin = "AuthenticAMD"  Id = 0x20f32  Stepping = 2
> > Features=0x178bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,
> >MCA,C MOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2,HTT>
> >   Features2=0x1<SSE3>
> >   AMD Features=0xe2500800<SYSCALL,NX,MMX+,<b25>,LM,3DNow+,3DNow>
> >   Hyperthreading: 2 logical CPUs
>
> Can this "I see hyperthreading, while there is no hyperthreading" cause
> performance degradation, for example by HTT defaults to off in the
> recent 5.x builds?


I just made some grep in /usr/src and 
found /usr/src/sys/amd64/amd64/identcpu.c, near the line #293:
.....
                        /*
                         * If this CPU supports hyperthreading then mention
                         * the number of logical CPU's it contains.
                         */
                        if (cpu_feature & CPUID_HTT &&
                            (cpu_procinfo & CPUID_HTT_CORES) >> 16 > 1)
                                printf("\n  Hyperthreading: %d logical CPUs",
                                    (cpu_procinfo & CPUID_HTT_CORES) >> 16);
...

I don't know all details but seem that cpu_feature contain CPUID_HTT bit....


/Alexander Konovalenko

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Royal Institute of Technology (KTH)
Nanostructure Physics Department, Albanova
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