Re: [Xen-devel] [PATCH v3 1/5] xen:rtds: towards work conserving RTDS

[Dario Faggioli <raistlin@xxxxxxxx>]

On Tue, 2017-10-10 at 19:17 -0400, Meng Xu wrote:
> Make RTDS scheduler work conserving without breaking the real-time
> guarantees.
> 
> VCPU model:
> Each real-time VCPU is extended to have an extratime flag
> and a priority_level field.
> When a VCPU's budget is depleted in the current period,
> if it has extratime flag set,
> its priority_level will increase by 1 and its budget will be
> refilled;
> othewrise, the VCPU will be moved to the depletedq.
> 
> Scheduling policy is modified global EDF:
> A VCPU v1 has higher priority than another VCPU v2 if
> (i) v1 has smaller priority_leve; or
> (ii) v1 has the same priority_level but has a smaller deadline
> 
> Queue management:
> Run queue holds VCPUs with extratime flag set and VCPUs with
> remaining budget. Run queue is sorted in increasing order of VCPUs
> priorities.
> Depleted queue holds VCPUs which have extratime flag cleared and
> depleted budget.
> Replenished queue is not modified.
> 
> Distribution of spare bandwidth
> Spare bandwidth is distributed among all VCPUs with extratime flag
> set,
> proportional to these VCPUs utilizations
> 
> Signed-off-by: Meng Xu <mengxu@xxxxxxxxxxxxx>
> 
Reviewed-by: Dario Faggioli <raistlin@xxxxxxxx>

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
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Dario Faggioli, Ph.D, http://about.me/dario.faggioli

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