Re: [Xen-devel] [PATCH] xen: sched: rtds: refactor code

[Meng Xu <mengxu@xxxxxxxxxxxxx>]

Hi Tianyang

On Wed, May 11, 2016 at 11:20 AM, Tianyang Chen <tiche@xxxxxxxxxxxxxx> wrote:
> No functional change:
>  -Various coding style fix
>  -Added comments for UPDATE_LIMIT_SHIFT.
>
> Use non-atomic bit-ops:
>  -Vcpu flags are checked and cleared atomically. Performance can be
>   improved with corresponding non-atomic versions since schedule.c
>   already has spin_locks in place.
>
> Suggested-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>

It's better to add the link to the thread that has the suggestion.

> @@ -930,7 +936,7 @@ burn_budget(const struct scheduler *ops, struct rt_vcpu 
> *svc, s_time_t now)
>      if ( svc->cur_budget <= 0 )
>      {
>          svc->cur_budget = 0;
> -        set_bit(__RTDS_depleted, &svc->flags);
> +        __set_bit(__RTDS_depleted, &svc->flags);
>      }
>
>      /* TRACE */
> @@ -955,7 +961,7 @@ burn_budget(const struct scheduler *ops, struct rt_vcpu 
> *svc, s_time_t now)
>   * lock is grabbed before calling this function

The comment says "lock is grabbed before calling this function".
IIRC,  we use __ to represent that we grab the lock before call this function.
Then this change violates the convention.

>   */
>  static struct rt_vcpu *
> -__runq_pick(const struct scheduler *ops, const cpumask_t *mask)
> +runq_pick(const struct scheduler *ops, const cpumask_t *mask)
>  {
>      struct list_head *runq = rt_runq(ops);
>      struct list_head *iter;
> @@ -964,9 +970,9 @@ __runq_pick(const struct scheduler *ops, const cpumask_t 
> *mask)
>      cpumask_t cpu_common;
>      cpumask_t *online;
>
> -    list_for_each(iter, runq)
> +    list_for_each ( iter, runq )
>      {
> -        iter_svc = __q_elem(iter);
> +        iter_svc = q_elem(iter);
>
>          /* mask cpu_hard_affinity & cpupool & mask */
>          online = cpupool_domain_cpumask(iter_svc->vcpu->domain);
> @@ -1028,7 +1034,7 @@ rt_schedule(const struct scheduler *ops, s_time_t now, 
> bool_t tasklet_work_sched
>      }
>      else
>      {
> -        snext = __runq_pick(ops, cpumask_of(cpu));
> +        snext = runq_pick(ops, cpumask_of(cpu));
>          if ( snext == NULL )
>              snext = rt_vcpu(idle_vcpu[cpu]);
>



Meng

-----------
Meng Xu
PhD Student in Computer and Information Science
University of Pennsylvania
http://www.cis.upenn.edu/~mengxu/

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