Messages in this thread | | | Date | Wed, 22 Mar 2006 06:19:16 +0100 | From | Knut Petersen <> | Subject | Re: [BUG] wrong bogomips values with kernel 2.6.16 |
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Linus Torvalds schrieb:
>That sounds correct. On x86, BogoMips these days is just a measure of how >fast the timestamp counter goes (multiplied by two for totally bogus >reasons), and a Pentium-M should have a fixed-frequency TSC that ticks at >the highest possible frequency of the CPU, regardless of what the real >frequency is. > > > Pentium 4 and Xeon model 3 and above increment the time stamp counter at a constant rate independent of the current cpu frequency.
All Pentium M, Xeon up to model 2 and the P6 family increment with every internal processor cycle.
This behaviour is documented in chapter 18.8 of IA-32 Intel® Architecture Software Developer’s Manual, Volume 3B: System Programming Guide, Part 2, Order Number: 253669-018, January 2006.
Because of your false assumption of a fixed-frequency TSC, your conclusions are false too. Scaling of the bogomips values should really happen, but the start value is wrong. For 800 MHz there should be a bogomips value of about 1598, for 1867 MHz a value of about 3730.
You asked for a full /proc/cpuinfo, here it is ...
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
cu, Knut
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