Re: [Xen-devel] [PATCH for 4.5 v4 1/4] xen: add real time scheduler rtds

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Sat, Sep 20, 2014 at 11:13 PM, Meng Xu <mengxu@xxxxxxxxxxxxx> wrote:
> This scheduler follows the Preemptive Global Earliest Deadline First
> (EDF) theory in real-time field.
> At any scheduling point, the VCPU with earlier deadline has higher
> priority. The scheduler always picks the highest priority VCPU to run on a
> feasible PCPU.
> A PCPU is feasible if the VCPU can run on this PCPU and (the PCPU is
> idle or has a lower-priority VCPU running on it.)
>
> Each VCPU has a dedicated period and budget.
> The deadline of a VCPU is at the end of each period;
> A VCPU has its budget replenished at the beginning of each period;
> While scheduled, a VCPU burns its budget.
> The VCPU needs to finish its budget before its deadline in each period;
> The VCPU discards its unused budget at the end of each period.
> If a VCPU runs out of budget in a period, it has to wait until next period.
>
> Each VCPU is implemented as a deferable server.
> When a VCPU has a task running on it, its budget is continuously burned;
> When a VCPU has no task but with budget left, its budget is preserved.
>
> Queue scheme:
> A global runqueue and a global depletedq for each CPU pool.
> The runqueue holds all runnable VCPUs with budget and sorted by deadline;
> The depletedq holds all VCPUs without budget and unsorted.
>
> Note: cpumask and cpupool is supported.
>
> This is an experimental scheduler.
>
> Signed-off-by: Meng Xu <mengxu@xxxxxxxxxxxxx>
> Signed-off-by: Sisu Xi <xisisu@xxxxxxxxx>
> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

Looks great! Thanks for all the hard work everyone.

Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>

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