Re: [Xen-devel] [PATCH v3 1/4] xen: add real time scheduler rtds

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 14.09.14 at 23:37, <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>

For everything except the meat of it (xen/common/sched_rt.c)
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
with one coding style nit:

> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -347,6 +347,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_max_vcpus_t);
>  #define XEN_SCHEDULER_CREDIT   5
>  #define XEN_SCHEDULER_CREDIT2  6
>  #define XEN_SCHEDULER_ARINC653 7
> +#define XEN_SCHEDULER_RTDS     8
> +
>  /* Set or get info? */
>  #define XEN_DOMCTL_SCHEDOP_putinfo 0
>  #define XEN_DOMCTL_SCHEDOP_getinfo 1
> @@ -368,6 +370,10 @@ struct xen_domctl_scheduler_op {
>          struct xen_domctl_sched_credit2 {
>              uint16_t weight;
>          } credit2;
> +        struct xen_domctl_sched_rtds{

Missing blank before opening brace.

Jan

> +            uint32_t period;
> +            uint32_t budget;
> +        } rtds;
>      } u;
>  };
>  typedef struct xen_domctl_scheduler_op xen_domctl_scheduler_op_t;



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