On Fri, 2009-09-25 at 16:48 +0200, Peter Zijlstra wrote: > On Thu, 2009-09-24 at 10:51 +1000, Benjamin Herrenschmidt wrote: > > On Tue, 2009-09-15 at 14:11 +0200, Peter Zijlstra wrote: > > > I still think its a layering violation... its the hypervisor manager > > > that should be bothered in what state an off-lined cpu is in. > > > > > That's not how our hypervisor works. > > Then fix it?
Are you serious ? :-) > CPU hotplug is terribly invasive and expensive to the kernel, doing > hotplug on a minute basis is just plain crazy. > > If you want a CPU in a keep it near and don't hand it back to the HV > state, why not use cpusets to isolate it and simply not run tasks on it? > > cpusets don't use stopmachine and are much nicer to the rest of the > kernel over-all. Gautham, what is the different in term of power saving between having it idle for long periods of time (which could do H_CEDE and with NO_HZ, probably wouln't need to wake up that often) and having it unplugged in a H_CEDE loop ? Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
