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Re: which program can test cpu speed

On Fri, Oct 26, 2018 at 09:16:47PM +0300, Reco wrote:
As far as I remember, the bogomips number has consistently been twice the current clock frequency on any x86 PCU I have ever run Linux on.

Either your math is off, or they've changed it.

$ lscpu | egrep '(Vendor|MHz|MIPS)' # This PC
Vendor ID:             GenuineIntel
CPU MHz:               1599.975
CPU max MHz:           3800.0000
CPU min MHz:           1600.0000
BogoMIPS:              6800.59

Who knows what "this pc" is. In this case bogomips is a little less than double, may be the system is configured to never exceed 3.4GHz (derated) or may be the difference between core and turbo or who knows what else. Would help to see CPU model. (In future, "Model name" is much more usefule than "Vendor".)

$ lscpu | egrep '(Vendor|MHz|MIPS)' # Certain VPS
Vendor ID:             GenuineIntel
CPU MHz:               2099.996
BogoMIPS:              4199.99

About double.


$ lscpu | egrep '(Vendor|MHz|MIPS)' # Xeon X5675
Vendor ID:             GenuineIntel
CPU MHz:               1600.000
BogoMIPS:              6117.70

x5675 is a 3.06GHz CPU that turbos to 3.46GHz, so bogomips is indeed about double the core frequency here. Older CPUs don't show min/max in lscpu output, only current frequency.

I spot checked a few systems here, found bogomips consistently about 2x max clock on skylake, haswell, xen+, silvermont, braswell and a couple of others. Heck, even the oldest thing I have that boots (a 200MHz pentium MMX) has a bogomips of 399.77 -- about double the MHz. The pentium pro family (+ ii & iii) got roughly the same bogomips as MHz. You have to go all the way back to the original pentiums, 486s, and 386s before you see major differences in the multipliers between CPUs. Anyway, the point remains--this is not useful as a benchmark.