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Date: Thu, 10 Aug 2017 14:41:03 +0200
From: Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] x86: Increase max vcpu number to 352
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To: Lan Tianyu <tianyu.lan@intel.com>
Cc: "Daniel P. Berrange" <berrange@redhat.com>, pbonzini@redhat.com, mst@redhat.com, qemu-devel@nongnu.org, ehabkost@redhat.com, rth@twiddle.net

2017-08-10 19:02+0800, Lan Tianyu:
> On 2017=E5=B9=B408=E6=9C=8810=E6=97=A5 18:26, Daniel P. Berrange wrote:
>> On Thu, Aug 10, 2017 at 06:08:07PM +0800, Lan Tianyu wrote:
>>> Intel Xeon phi chip will support 352 logical threads. For HPC
>>> usage case, it will create a huge VM with vcpus number as same as hos=
t
>>> cpus. This patch is to increase max vcpu number to 352.
>>=20
>> If we pick arbitray limits based on size of physical CPUs that happen
>> to be shipping today, we'll continue the cat+mouse game forever traili=
ng
>> latest CPUs that vendors ship.
>>=20
>> IMHO we should pick a higher number influenced by technical constraint=
s
>> of the q35 impl instead. eg can we go straight to something like 512 o=
r
>> 1024  ?
>=20
> Sure. 512 should be enough and some arrays is defined according to max
> vcpu number.

Hm, which arrays are that?  I was thinking it is safe to bump it to
INT_MAX as the number is only used when setting global max_cpus.

Thanks.