Messages in this thread | | | Date | Tue, 05 Jun 2012 08:27:06 -0700 | From | Arjan van de Ven <> | Subject | Re: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi |
| |
On 6/5/2012 7:17 AM, Alan Stern wrote: > On Mon, 4 Jun 2012, Arjan van de Ven wrote: > >>> I disagree. Deactivating a cpu for power saving is halfway to hotplug >>> anyway. I'd rather unify the two cases, where we can specify how dead a >>> CPU should be, than have individual archs and boards do random hacks. >> >> well on PC's there really is no difference at least; >> idle equals "all power removed" already there. > > This doesn't sound right at all. Len Brown has often told us that on > Intel chips, power can't be removed from a package until _all_ the > cores in the package are idle.
but "cpu hotplug" does not change that.. in fact, cpu hotplug is implemented as a C state...
and to be specific; power will get removed from the cores one at a time. you just cannot remove the power from the memory controller until the last one is off.
| |