Hi... On Mon, Jun 13, 2011 at 15:26, naveen yadav <yad.naveen@gmail.com> wrote:
Dear All,
We are using ARM cortex a9. In below scenario, I want help.
May I take x86 as point of view here?
Multi-Core Power Saving Hot plug feature allows for making a processor offline and let the system run as if there is only a single core. Now,comes the scenario - Let there are '2' cores in the system both running at a load of 40% (i.e. total load 80%), now in this case ideally '1' CPU is sufficient. So, if we make 2nd Core offline that will make the system execute everything on core '1'.
The thing is, you need to measure the real frequency step or, to be precide, C/P state. If that 80 % on single processor, let's say brought processor into highest C and P state *all the time*, there is a chance the power consumption exceed 2 processor that by average in mid or low C/P state (and they got chance to get idle more often too). So physically, I agree 1 processor consume less power than 2 processor. But that depends entirely on the load. And, I believe it also depends on which power scaling governor you use too.
But will there be any power saving if we make any core offline under scenarios like this? Or will this have extra overhead? What are the pros and cons of working like this on Multi-Core?
Regards Naveen
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