Subject: Re: [linux-audio-user] CPU clock - beware
From: Ryan Underwood (nemesis-lists_AT_icequake.net)
Date: Mon Jul 26 2004 - 05:50:40 EEST
On Sun, Jul 25, 2004 at 03:13:37AM +0100, tim hall wrote:
> sure:
> ~$ cat /proc/cpuinfo
> processor : 0
> vendor_id : GenuineIntel
> cpu family : 6
> model : 8
> model name : Celeron (Coppermine)
> stepping : 6
> cpu MHz : 896.977
> cache size : 128 KB
> fdiv_bug : no
> hlt_bug : yes
> 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 pse36 mmx fxsr sse
> bogomips : 1789.13
Yeah, definitely overclocked. There are no Celerons with 128KB cache
that run with a 100Mhz bus, AFAIK.
> > "cpu MHz" the real current speed
> > "bogomips" issome weird timing value I have no idea what it means exactly
> It's a semi-arbitrary benchmarking value, usually twice the processor speed.
> AFAIU.
Depends on the chip. It is used to calculate the amount of time spent
in a particular kernel delay loop. Some chips run this code faster or
slower than others. It's not a benchmark as much as a calibration
value.
> This is what I guessed, I'm using the values specified in the manual for a
> Coppermine FC-PGA 600, so:
Oops. They could be referring to a PIII Coppermine, you know...
> at 3x clock ratio I get:
> CPU (I assume this is FSB) 100
> PCI 33
> AGP 66
> The display cache runs at 100MHz too, a 1:1 ratio seems logical.
1:1 CPU<->AGP ratio? That's not going to work well at 100MHZ FSB.
> I think I might read it now. I'm a bit confused as to why my system thinks
> it's running a 896MHz CPU, But so far there's no overt signs that it isn't
> happy, so I'll prod it a bit and see ;-)
897MHz is just the FSB * 9. It doesn't run exactly at 100MHz because it
would be impossible to do so while maintaining synchronicity with a
33MHz PCI bus. 33MHz is actually 33.something, so you end up with
99.something when the FSB is running at 3x the PCI frequency.
-- Ryan Underwood, <nemesis_AT_icequake.net>
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