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[Xen-users] Define caps and weights per-VCPU in credit scheduler!

  • To: xen-devel@xxxxxxxxxxxxxxxxxxx, xen-users@xxxxxxxxxxxxxxxxxxx
  • From: "Vahid Kazempour" <kazempour@xxxxxxxxx>
  • Date: Tue, 14 Oct 2008 17:48:02 -0700
  • Cc:
  • Delivery-date: Tue, 14 Oct 2008 17:48:42 -0700
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Hi all,

As far as I know in credit scheduler we can only define weights and caps for each VM, and the scheduler apply these credits to all VCPUs belongs to the VM (i.e. if we setting a limit in the form of cap it will affect all VCPUs in the VM).

Considering a scenario that we have heterogeneous cores in the system (fast and slow cores) and VMs are competing on fast cores.
One policy for fare sharing of fast cores is to share them based on the number of VCPUs. This may require to define different limits on CPU usage for each VCPU which is not necessarily same for all VCPUs belong to a VM. In this scenario does it make sense to have weights and caps in credit scheduler based on VCPUs instead of VMs?  Is it possible to define different per-VCPU limits for a single VM without modifying the scheduler code?


Vahid Kazempour

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