Re: [PATCH] Cosmetic change to schedule_cpu_switch

[Keir Fraser <keir.fraser@eu.citrix.com>]

Thanks, I'll fold this into my next patch. You'll see from my recent
changesets that I'm currently tearing into the scheduler and cpupool code as
part of my CPU hotplug cleanup. I think there must be scope for further
rationalisation of the sched-if interfaces as the sched_ops have sprouted a
bewildering array of extra functions for cpupool support. I'm sure it's over
complicated.

 -- Keir

On 18/05/2010 21:22, "George Dunlap" <George.Dunlap@eu.citrix.com> wrote:

> Using 'v' generally means that you mean any generic vcpu, not
> a particular vcpu.  In this case, we always use the idle vcpu;
> I think naming it explicitly idle_vcpu makes the code easier to grok.
> 
> No functional changes.
> 
> Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
> 
> diff -r c6db509d7e46 -r ebad6ba33a8f xen/common/schedule.c
> --- a/xen/common/schedule.c Tue May 18 15:18:26 2010 +0100
> +++ b/xen/common/schedule.c Tue May 18 15:22:27 2010 -0500
> @@ -1151,7 +1151,7 @@
>  void schedule_cpu_switch(unsigned int cpu, struct cpupool *c)
>  {
>      unsigned long flags;
> -    struct vcpu *v;
> +    struct vcpu *idle_vcpu;
>      void *ppriv, *ppriv_old, *vpriv = NULL;
>      struct scheduler *old_ops = per_cpu(scheduler, cpu);
>      struct scheduler *new_ops = (c == NULL) ? &ops : c->sched;
> @@ -1159,21 +1159,21 @@
>      if ( old_ops == new_ops )
>          return;
>  
> -    v = per_cpu(schedule_data, cpu).idle;
> +    idle_vcpu = per_cpu(schedule_data, cpu).idle;
>      ppriv = SCHED_OP(new_ops, alloc_pdata, cpu);
>      if ( c != NULL )
> -        vpriv = SCHED_OP(new_ops, alloc_vdata, v, v->domain->sched_priv);
> +        vpriv = SCHED_OP(new_ops, alloc_vdata, idle_vcpu,
> idle_vcpu->domain->sched_priv);
>  
>      spin_lock_irqsave(per_cpu(schedule_data, cpu).schedule_lock, flags);
>  
>      if ( c == NULL )
>      {
> -        vpriv = v->sched_priv;
> -        v->sched_priv = per_cpu(schedule_data, cpu).sched_idlevpriv;
> +        vpriv = idle_vcpu->sched_priv;
> +        idle_vcpu->sched_priv = per_cpu(schedule_data, cpu).sched_idlevpriv;
>      }
>      else
>      {
> -        v->sched_priv = vpriv;
> +        idle_vcpu->sched_priv = vpriv;
>          vpriv = NULL;
>      }
>      SCHED_OP(old_ops, tick_suspend, cpu);
> @@ -1181,7 +1181,7 @@
>      ppriv_old = per_cpu(schedule_data, cpu).sched_priv;
>      per_cpu(schedule_data, cpu).sched_priv = ppriv;
>      SCHED_OP(new_ops, tick_resume, cpu);
> -    SCHED_OP(new_ops, insert_vcpu, v);
> +    SCHED_OP(new_ops, insert_vcpu, idle_vcpu);
>  
>      spin_unlock_irqrestore(per_cpu(schedule_data, cpu).schedule_lock, flags);
>  
> 
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