On Thu, 2011-02-24 at 21:47 +0100, Thomas Gleixner wrote: > On Thu, 24 Feb 2011, Peter Zijlstra wrote: > > > On Thu, 2011-02-24 at 15:24 -0500, Nicolas Pitre wrote: > > > > > Most SMP ARM processors are going to use it soon. Powering down idle > > > cores provides substantial power saving. > > > > And why can't regular idle paths be used? CPU hotplug is a massively > > expensive operation. > > To achieve the same result from idle, you need to exclude the core > from any unwanted wakeup. At the moment cpu unplug is the only way to > achieve that. Right, everything is a nail because all we have is a hammer like. > If you want to do the same from idle, then we need the isolation > features Frederic is working on for RT/HPC. > > They allow us to isolate cores completely for totaly different > reasons, but it could be resused to provide full isolation of a core > in a very deep power state. Exactly. > That would solve the problem w/o going through kstompmachine Right, kstopmachine is a large part of the problem, but cpu hotplug really does an insane amount of work if all you want is to idle the core. -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
