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From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 23 May 2012 09:54:04 +0200
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Subject: Re: [Qemu-devel] [PATCH 1/2] sched: add virt sched domain for the
	guest
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To: Liu Ping Fan <kernelfans@gmail.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, Ingo Molnar <mingo@redhat.com>, Avi Kivity <avi@redhat.com>, Anthony Liguori <anthony@codemonkey.ws>

On Wed, 2012-05-23 at 14:32 +0800, Liu Ping Fan wrote:
> From: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
>=20
> The guest's scheduler can not see the numa info on the host and
> this will result to the following scene:
>   Supposing vcpu-a on nodeA, vcpu-b on nodeB, when load balance,
> the tasks' pull and push between these vcpus will cost more. But
> unfortunately, currently, the guest is just blind to this.
>=20
> This patch want to export the host numa info to the guest, and help
> guest to rebuild its sched domain based on host's info.

Hell no, we're not going to export sched domains, if kvm/qemu wants this
its all in sysfs.

The whole sched_domain stuff is a big enough pain as it is, exporting
this and making it a sodding API is the worst thing ever.=20

Whatever brainfart made you think this is needed anyway? sysfs contains
the host topology, qemu can already create whatever guest topology you
want (see the -smp and -numa arguments), so what gives?