Re: [Xen-devel] [PATCH RFC v2 1/4] xen: add real time scheduler rt

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 29.07.14 at 03:52, <mengxu@xxxxxxxxxxxxx> wrote:
> --- a/xen/common/schedule.c
> +++ b/xen/common/schedule.c
> @@ -68,6 +68,7 @@ static const struct scheduler *schedulers[] = {
>      &sched_sedf_def,
>      &sched_credit_def,
>      &sched_credit2_def,
> +    &sched_rt_def,
>      &sched_arinc653_def,
>  };

Is the insertion as other than last item (as one would expect for a
new addition) intentional? Not that I think this matters much, but
I'm still curious.

> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -339,6 +339,18 @@ struct xen_domctl_max_vcpus {
>  typedef struct xen_domctl_max_vcpus xen_domctl_max_vcpus_t;
>  DEFINE_XEN_GUEST_HANDLE(xen_domctl_max_vcpus_t);
>  
> +/*
> + * This structure is used to pass to rt scheduler from a 
> + * privileged domain to Xen
> + */
> +struct xen_domctl_sched_rt_params {
> +    /* get vcpus' info */
> +    int64_t period; /* s_time_t type */
> +    int64_t budget;
> +    int     index;

Are all these really meaningfully signed quantities?

Also, you need to pad the structure to a multiple of 8 bytes, or
its layout will differ between 32- and 64-bit (tool stack) callers.

> @@ -367,6 +382,15 @@ struct xen_domctl_scheduler_op {
>          struct xen_domctl_sched_credit2 {
>              uint16_t weight;
>          } credit2;
> +        struct xen_domctl_sched_rt{
> +            /* get vcpus' params */
> +            XEN_GUEST_HANDLE_64(xen_domctl_sched_rt_params_t) vcpu;
> +            uint16_t nr_vcpus;
> +            /* set one vcpu's params */
> +            uint16_t vcpu_index;
> +            int64_t period;
> +            int64_t budget;
> +        } rt;

Mostly the same comments here, just that the padding here needs to
go in the middle.

Jan


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