Re: [Question] AMD opteron can support CPUfreq by per core ?

[Simon Arlott <simon@fire.lp0.eu>]

> On Thu, Oct 30, 2008 at 2:06 PM, MinChan Kim <minchan.kim@gmail.com> wrote:
>> Hi,  all,
>>
>> I want to test CPUfreq function in  AMD opteron quad-core series.
>> But I am not sure linux in now can support CPUfreq for ADM opteron by per core ?
>> What I mean is not controling to put together 2 core by one package
>> but control by per core.
>> After all, I want to control all 4 cpu separetely.
>>
>> Is is possible? If it is possible, What kinds of model can support ?

All Quad-Core AMD Opterons support using a separate CPU frequency per core.
All four cores are all independent, but afaik you'll only get a reduction in 
voltage based on the highest speed of all four cores.

You may want to ensure you get a motherboard with DDPM so the CPU and memory 
controller power is independent. http://www.tyan.com/tech/ddpm.aspx

Make sure you use a recent kernel which handles C1E properly.


On 31/10/08 03:06, Peter Teoh wrote:
> check this out:
> 
> http://osdir.com/ml/kernel.cpufreq/2004-07/msg00012.html
> 
> from the reply, since the power management flag is at the per-core
> level (check /proc/cpuinfo), all control can be done at the per-core
> level, hard-ware wise.   (not sure of Linux Kernel itself)
> 
> But at least 4 flags must be present (read above email):   ts, ttp, fid, vid.
> 
> I must also say this is the first time I am aware of these flags too :-).

Don't top post.

I've never heard of these flags - that email is from 2004.

model name	: Quad-Core AMD Opteron(tm) Processor 2354

flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good pni monitor cx16 lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs

[    5.569030] powernow-k8:    0 : pstate 0 (2200 MHz)
[    5.569136] powernow-k8:    1 : pstate 1 (2000 MHz)
[    5.569233] powernow-k8:    2 : pstate 2 (1700 MHz)
[    5.569330] powernow-k8:    3 : pstate 3 (1400 MHz)
[    5.569434] powernow-k8:    4 : pstate 4 (1100 MHz)
-- 
Simon Arlott