Re: [Xen-devel] [PATCH v2] credit: generalize __vcpu_has_soft_affinity()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.03.15 at 14:23, <dario.faggioli@xxxxxxxxxx> wrote:
> Which means that, yes, this part of the condition must loose the '!', or
> have the arguments of the call to cpumask_subset() switched. I
> personally prefer the former:
> 
>     return !cpumask_subset(cpupool_online_cpumask(vc->domain->cpupool),
>                            vc->cpu_soft_affinity) &&
>            cpumask_subset(vc->cpu_soft_affinity, vc->cpu_hard_affinity) &&
>            cpumask_intersects(vc->cpu_soft_affinity, mask);

The form without ! and with operands swapped isn't correct afaict,
since subset(x,y) is not the same as !subset(y,x). In particular
when the two are identical, they are also subsets of one another.
Which is precisely a case you don't want the "soft" scheduling
cycle to be gone through.

Jan


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