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xiongye
n00b
Joined: 11 Aug 2003
Posts: 6
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 Posted: Mon Apr 05, 2004 5:09 pm Post subject: weird cpu infomations. |
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I have two p4 desktops. Here is cpu info of them.
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 0
model name : Intel(R) Pentium(R) 4 CPU 1300MHz
stepping : 7
cpu MHz : 1285.738
cache size : 256 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 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm
bogomips : 2531.32
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 0
model name : Intel(R) Pentium(R) 4 CPU 1300MHz
stepping : 7
cpu MHz : 1296.081
cache size : 256 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 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm
bogomips : 2555.90
the two cpus are exactly same, but why the later one is a little bit faster than the first one. |
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furanku
l33t
Joined: 08 May 2003
Posts: 905
Location: Hamburg, Germany
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| Posted: Mon Apr 05, 2004 6:51 pm Post subject: |
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From the BogoMips Mini-HOWTO
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From Linus Torvalds, torvalds@cc.helsinki.fi, explaining about the variation one may see in the BogoMips rating, in c.o.l.development, at 28 April 1994
`The BogoMips calculation loop is "quantizised", so you're most likely to get the exact same number all the time. You usually will get different numbers only if the speed is just on the "edge", when small variations (different time for interrupt ticks etc) will make it jump from one value to the other.'
If a kernel is not compiled specifically for the pertaining CPU, also some (even large) variations of the BogoMips ratings can occur, mainly due to erroneous alignment. This problem apparently only occurs on the various x86 CPUs (Intel and clones). Fortunately it can easily be solved: recompile the kernel specifically for your CPU.
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discowombat
Tux's lil' helper
Joined: 19 Sep 2003
Posts: 106
Location: The Cornfields
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| Posted: Mon Apr 05, 2004 7:21 pm Post subject: |
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I've got a hyperthreaded pentium4, and the bogomips for the "2" processors (actually the same processor) are 5128.19 and 5177.34. I've never really worried about it, from what i have read it's not the most accurate way to benchmark a system anyways.
_________________
One by one the penguins steal my sanity |
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morologous
n00b
Joined: 31 Mar 2004
Posts: 7
Location: Baltimore-Washington Metro
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| Posted: Mon Apr 05, 2004 8:02 pm Post subject: Were you referring to... |
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Were you referring to the Mhz? I do note that one appears to have a markedly slower Mhz than it's companion (one 1285 and one 1296).
Is this what you're asking about? If not, than I would concur with the previous posters. If it is, are the cpuinfo draws from the same motherboard with two different processors, or two different motherboards (to which I would perhaps attribute some variance in clock speed).
Can any one else provide information regarding this? |
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xiongye
n00b
Joined: 11 Aug 2003
Posts: 6
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| Posted: Tue Apr 06, 2004 5:21 am Post subject: |
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thank you furanku for your explaination on bogomips.
Then how about the cpu freq. The configrations of the two computers are exactly same. I found my fortran program was ~10% faster running on the later computer. So what makes these two computers exhibit different cpu power? |
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Kernel & Hardware
