Messages in this thread | | | Subject | Re: [PATCH -v2 5/5] x86: use dmi check to treat disabled cpus as hotplug cpus. | From | Suresh Siddha <> | Date | Tue, 12 Jan 2010 18:21:08 -0800 |
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On Tue, 2010-01-12 at 18:13 -0800, Yinghai Lu wrote: > On 01/12/2010 06:06 PM, Suresh Siddha wrote: > > On Tue, 2010-01-12 at 17:55 -0800, Yinghai Lu wrote: > >> you mean this blacklist could be too long? > > > > yes. > > > >> > >> switch to whitelist for the box can treat disabled cpus as hotplug > >> cpus? > > > > Do we really need all this? Systems which support physical hotplug > > typically have lot's of cpu's (mostly will have atleast > 8). Even if we > > really need to identify, then perhaps we can check if ACPI has any hints > > regarding the physical hotplug support at boot time (we should check > > with Andi Kleen or Len Brown on this). > > > > For now, I think we can keep it simple by using the detected enabled > > cpu's. > > sth like this ?
Well, I was referring more to the apic model selection than the prefill case. About this possible cpu's, will the wastage be more than few kb for few disabled cpu's.
thanks, suresh
> --- > arch/x86/kernel/smpboot.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > Index: linux-2.6/arch/x86/kernel/smpboot.c > =================================================================== > --- linux-2.6.orig/arch/x86/kernel/smpboot.c > +++ linux-2.6/arch/x86/kernel/smpboot.c > @@ -1190,7 +1190,6 @@ early_param("possible_cpus", _setup_poss > * - Ashok Raj > * > * Three ways to find out the number of additional hotplug CPUs: > - * - If the BIOS specified disabled CPUs in ACPI/mptables use that. > * - The user can overwrite it with possible_cpus=NUM > * - Otherwise don't reserve additional CPUs. > * We do this because additional CPUs waste a lot of memory. > @@ -1205,7 +1204,7 @@ __init void prefill_possible_map(void) > num_processors = 1; > > if (setup_possible_cpus == -1) > - possible = num_processors + disabled_cpus; > + possible = num_processors; > else > possible = setup_possible_cpus; >
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