Messages in this thread | | | Date | Mon, 13 Nov 2006 20:04:52 +0100 | From | Ingo Molnar <> | Subject | Re: [patch] genapic: optimize & fix APIC mode setup |
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* Siddha, Suresh B <suresh.b.siddha@intel.com> wrote:
> On Mon, Nov 13, 2006 at 07:42:56PM +0100, Ingo Molnar wrote: > > * Siddha, Suresh B <suresh.b.siddha@intel.com> wrote: > > > Not really. That chipset belongs to a MP platform and with your > > > proposed patch, we will endup using clustered APIC mode and will hit > > > the issue(in the presence of cpu hotplug) mentioned in that URL. > > > > hm, why does it end up in clustered mode? Cluster mode should only > > trigger if the APIC IDs go beyond 16. > > go beyond '8' not 16. With Dual-core+HT these MP platforms will have > 16 logical cpus.
yes - then the APIC ids will go beyond 15.
> > but i'd be fine with never going into cluster mode, instead always > > using physical flat mode when having more than 8 APICs (independent > > of the presence of CPU hotplug). On small systems, logical flat mode > > is what is the best-tested variant (it's also slightly faster). > > Ok.
ok, that's really good. Is there any 'weird' platform that you are aware of that absolutely needs clustered APIC mode (because it has no physical delivery mode or something)?
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