On Wed, Aug 22, 2012 at 06:02:48AM -0700, Arjan van de Ven wrote: > On 8/21/2012 10:41 PM, Mike Galbraith wrote: > > For my dinky dual core laptop, I suspect you're right, but for a more > > powerful laptop, I'd expect spread/don't to be noticeable. > > yeah if you don't spread, you will waste some power. > but.. current linux behavior is to spread. > so we can only make it worse.
Right. For a single socket system the only thing you can do is use two threads in preference to using two cores. That'll keep an extra core in a deep C state for longer, at the cost of keeping the package out of a deep C state for longer. There might be a win if the two processes benefit from improved L1 cache locality, or if you're talking about short periodic work, but for the majority of cases I'd expect Arjan to be completely correct here. Things get more interesting with multi-socket systems, but that's beyond the laptop use case. -- Matthew Garrett | mj...@srcf.ucam.org -- 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/
