Re: [Xen-devel] [PATCH v3 09/14] xen: sched: DOMCTL_*vcpuaffinity works with hard and soft affinity

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.11.13 at 19:55, Dario Faggioli <dario.faggioli@xxxxxxxxxx> wrote:
> On mar, 2013-11-19 at 16:39 +0000, Jan Beulich wrote:
>> >>> On 18.11.13 at 19:17, Dario Faggioli <dario.faggioli@xxxxxxxxxx> wrote:
>> > +                online = cpupool_online_cpumask(v->domain->cpupool);
>> > +                cpumask_and(new_affinity, online, v->cpu_hard_affinity);
>> > +                if ( op->u.vcpuaffinity.flags & XEN_VCPUAFFINITY_SOFT)
>> > +                    cpumask_and(new_affinity, new_affinity,
>> > +                                v->cpu_soft_affinity);
>> > +
>> > +                ret = cpumask_to_xenctl_bitmap(
>> > +                    &op->u.vcpuaffinity.eff_cpumap, new_affinity);
>> 
>> Considering that you have two bitmaps available from the caller,
>> can't you just return both when both flags are set?
>> 
> Well, it's true that there are two cpumaps, but only one is meant to be
> an output parameter.

"meant to be" based on what? Surely not because so far it was that
way - as you say further down, this is not an interface required to
be stable.

> Also, I think this is more useful like this, i.e.,
> returning either:
>  - hard-affinity&online
>  - hard-affinity&soft-affinity&online,
> 
> As it can be seen in the libxl patch (in the new series).
> 
> Therefore, I kept this interface as it was here, also considering that:
>  - it's pretty late to re-re-redesign;
>  - neither this nor the xc one are stable interfaces, so we can come
>    back and revisit this later, if we want to.
> 
> Do you think this could be acceptable?

I wouldn't veto it, but I also dislike reduced flexibility when more
flexibility is obviously achievable without much effort.

Jan


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