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Re: [Xen-devel] credit based scheduler

  • To: xen-devel@xxxxxxxxxxxxxxxxxxx
  • From: "Molle Bestefich" <molle.bestefich@xxxxxxxxx>
  • Date: Wed, 21 Jun 2006 21:39:17 +0200
  • Delivery-date: Wed, 21 Jun 2006 12:39:47 -0700
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  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Emmanuel Ackaouy wrote:
The credit scheduler is an SMP CPU scheduler. It is designed such
that no physical CPU will ever idle if there is a waiting
runnable VCPU on the host. We call this being work conserving.

3 active UP guests on a 2CPU host each get 33% of the total CPU
available; The credit scheduler takes care of migrating guest
VCPUs across physical CPUs to achieve this transparently.

Migrating 1 VCPU across 2 CPUs, or swapping all 3 VCPUs around in a

Sounds like this algorithm is an evil killer of CPU cache performance to me :-).

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