From: Gleb Natapov <gleb@redhat.com>
To: "Wei, Bing (WeiBing, MCXS-SH)" <bing.wei@hp.com>
Cc: "Vinod, Chegu" <chegu_vinod@hp.com>,
Sasha Levin <levinsasha928@gmail.com>, KVM <kvm@vger.kernel.org>
Subject: Re: KVM_MAX_VCPUS
Date: Wed, 17 Oct 2012 09:21:41 +0200 [thread overview]
Message-ID: <20121017072141.GA7343@redhat.com> (raw)
In-Reply-To: <641B6FBA78EBA54CAA529D8D0E4DF811073642E0@G1W3650.americas.hpqcorp.net>
On Wed, Oct 17, 2012 at 02:57:15AM +0000, Wei, Bing (WeiBing, MCXS-SH) wrote:
> For pCPU/core and VCPUS/logical cpu mapping, It should be 8 multiple. 254 is reasonable. Or something I miss?
>
I am not sure what do you mean. Can you clarify?
> -----Original Message-----
> From: kvm-owner@vger.kernel.org [mailto:kvm-owner@vger.kernel.org] On Behalf Of Vinod, Chegu
> Sent: Sunday, October 14, 2012 9:43 PM
> To: Gleb Natapov
> Cc: Sasha Levin; KVM
> Subject: Re: KVM_MAX_VCPUS
>
> On 10/14/2012 2:08 AM, Gleb Natapov wrote:
> > On Sat, Oct 13, 2012 at 10:32:13PM -0400, Sasha Levin wrote:
> >> On 10/13/2012 06:29 PM, Chegu Vinod wrote:
> >>> Hello,
> >>>
> >>> Wanted to get a clarification about KVM_MAX_VCPUS(currently set to 254)
> >>> in kvm_host.h file. The kvm_vcpu *vcpus array is sized based on KVM_MAX_VCPUS.
> >>> (i.e. a max of 254 elements in the array).
> >>>
> >>> An 8bit APIC id should allow for 256 ID's. Reserving one for Broadcast should
> >>> leave 255 ID's. Is there one more ID reserved for some other purpose ? (hence
> >>> leading to KVM_MAX_VCPUS being set to 254 and not 255).
> >> Another ID goes to the IO-APIC.
> >>
> > This is not really needed on KVM. We can enlarge KVM_MAX_VCPUS to 255.
>
> Thanks for clarification! ( We did suspect the IO-APIC...but weren't
> quite sure).
>
> Vinod
> >
> > --
> > Gleb.
> > .
> >
>
> --
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> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Gleb.
prev parent reply other threads:[~2012-10-17 7:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-13 22:29 KVM_MAX_VCPUS Chegu Vinod
2012-10-14 2:32 ` KVM_MAX_VCPUS Sasha Levin
2012-10-14 9:08 ` KVM_MAX_VCPUS Gleb Natapov
2012-10-14 13:42 ` KVM_MAX_VCPUS Chegu Vinod
2012-10-17 2:57 ` KVM_MAX_VCPUS Wei, Bing (WeiBing, MCXS-SH)
2012-10-17 7:21 ` Gleb Natapov [this message]
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