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From: "Radim Krčmář" <rkrcmar@redhat.com>
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
Subject: Re: [Qemu-devel] [PATCH] x86: Increase max vcpu number to 352
Date: Thu, 10 Aug 2017 14:41:03 +0200	[thread overview]
Message-ID: <20170810124102.GA21850@flask> (raw)
In-Reply-To: <00cb01a4-5c27-fc69-d3ae-0653aa54b121@intel.com>

2017-08-10 19:02+0800, Lan Tianyu:
> On 2017年08月10日 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 host
>>> cpus. This patch is to increase max vcpu number to 352.
>> 
>> 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 trailing
>> latest CPUs that vendors ship.
>> 
>> IMHO we should pick a higher number influenced by technical constraints
>> of the q35 impl instead. eg can we go straight to something like 512 or
>> 1024  ?
> 
> 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.

  reply	other threads:[~2017-08-10 12:48 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-10 10:08 [Qemu-devel] [PATCH] x86: Increase max vcpu number to 352 Lan Tianyu
2017-08-10 10:26 ` Daniel P. Berrange
2017-08-10 11:02   ` Lan Tianyu
2017-08-10 12:41     ` Radim Krčmář [this message]
2017-08-10 18:16       ` Eduardo Habkost
2017-08-10 19:22         ` Radim Krčmář
2017-08-11  6:07           ` Lan Tianyu
2017-08-10 12:13 ` Paolo Bonzini
2017-08-10 13:52   ` Daniel P. Berrange
  -- strict thread matches above, loose matches on Subject: below --
2017-08-10  3:58 Lan Tianyu
2017-08-10 18:08 ` Konrad Rzeszutek Wilk
2017-08-11 11:51   ` Eduardo Habkost

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