On 8/15/2012 9:34 AM, Matthew Garrett wrote: > On Wed, Aug 15, 2012 at 01:05:38PM +0200, Peter Zijlstra wrote: >> On Mon, 2012-08-13 at 20:21 +0800, Alex Shi wrote: >>> It bases on the following assumption: >>> 1, If there are many task crowd in system, just let few domain cpus >>> running and let other cpus idle can not save power. Let all cpu take the >>> load, finish tasks early, and then get into idle. will save more power >>> and have better user experience. >> >> I'm not sure this is a valid assumption. I've had it explained to me by >> various people that race-to-idle isn't always the best thing. It has to >> do with the cost of switching power states and the duration of execution >> and other such things. > > This is affected by Intel's implementation - if there's a single active
not just intel.. also AMD basically everyone who has the memory controller in the cpu package will end up with a restriction very similar to this. (this is because the exit-from-self-refresh latency is pretty high.. at least in DDR2/3) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
