Re: [PATCH v5 for Xen 4.7 3/4] libxl: enable per-VCPU parameter settings for RTDS scheduler

[Wei Liu <wei.liu2@citrix.com>]

On Tue, Feb 09, 2016 at 01:00:37PM +0100, Dario Faggioli wrote:
[...]
> So, it looks to me that this function can be split in two. One would be
> the actual sched_rtds_vcpus_params_set(), and it will do what is being
> done above here.
> 
> The other one would be something like
> sched_rtds_vcpus_params_set_all(), and it will do what is being done
> below here.
> 
> About scinfo->num_vcpus, I think it would be fine for
> sched_rtds_vcpus_params_set() to enforce it being > 0, and erroring out
> if not.
> 
> On the other hand, in sched_rtds_vcpus_params_set_all(), since the
> semantic is "use this set of params for all vcpus", I think it would be
> fine to enforce scinfo->num_vcpus == 1 (and maybe even
> scinfo.vcpus[0].vcpuid == LIBXL_SCHED_PARAM_VCPU_INDEX_DEFAULT).
> 
> 
> Now, for external callers (like xl, but also like any other toolstack
> wanting to build on top of libxl).
> 
> If you think a 'set all vcpus' function would be useufl (as it is
> probably the case), you can define a libxl API function called
> libxl_vcpus_params_set_all(), doing exactly the same thing that
> libxl_vcpus_params_set() is doing, but calling the
> sched_rtds_vcpus_params_set_all() internal function.
> 
> Chong, do you think this could work?
> Wei, what do you think of the resulting API?

Introducing a _all function sounds reasonable.

Wei.