Re: [BUG] wrong bogomips values with kernel 2.6.16

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Linus Torvalds wrote:

On Wed, 22 Mar 2006, Knut Petersen wrote:
All Pentium M, Xeon up to model 2 and the P6 family increment with every
internal processor cycle.

Just to humor me. Try the bogomips loop in user space with something like the appended (make sure the frequency is fixed to the lowest frequency).

		Linus
No problem ...

linux:~ # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
1867000 1600000 1333000 1067000 800000

linux:~ # echo 800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed;cat /proc/cpuinfo;./test
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 1.86GHz
stepping        : 8
cpu MHz         : 800.000
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tmpbe nx est tm2
bogomips        : 3730.27

TSC: 798.307872 MHz




linux:~ # echo 1067000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed;cat /proc/cpuinfo;./test
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 1.86GHz
stepping        : 8
cpu MHz         : 1067.000
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tmpbe nx est tm2
bogomips        : 4975.25

TSC: 1064.407897 MHz



linux:~ # echo 1333000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed;cat /proc/cpuinfo;./test
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 1.86GHz
stepping        : 8
cpu MHz         : 1333.000
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tmpbe nx est tm2
bogomips        : 6215.57

TSC: 1330.511688 MHz


linux:~ # echo 1600000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed;cat /proc/cpuinfo;./test
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 1.86GHz
stepping        : 8
cpu MHz         : 1600.000
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tmpbe nx est tm2
bogomips        : 7460.55

TSC: 1596.612533 MHz


linux:~ # echo 1867000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed;cat /proc/cpuinfo;./test
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 1.86GHz
stepping        : 8
cpu MHz         : 1867.000
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tmpbe nx est tm2
bogomips        : 8705.53

TSC: 1862.715048 MHz


I tried kernel _2.6.15_ too - it´s even more broken:

linux:~ # cat /proc/cpuinfo;./test
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 13
model name      : Intel(R) Pentium(R) M processor 1.86GHz
stepping        : 8
cpu MHz         : 4347.853
cache size      : 2048 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tmpbe nx est tm2
bogomips        : 8702.35

TSC: 1863.086854 MHz

Isn´t that nice? I´m able to overclock my 1.86 MHz cpu to stable 4.35 MHz
with just a passive heatsink ;-)))

cu,
Knut
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