Re: Xen Platform QoS design discussion

["Jan Beulich" <JBeulich@suse.com>]

>>> On 01.05.14 at 02:56, <dongxiao.xu@intel.com> wrote:
>> From: Ian Campbell [mailto:Ian.Campbell@citrix.com]
>> Have you asked yourself whether this information even needs to be
>> exposed all the way up to libxl? Who are the expected consumers of this
>> interface? Are they low-level CLI tools (i.e. like xenpm is) or are you
>> expecting toolstacks to plumb this information all the way up to their
>> GUI or CLI (e.g. xl or virsh)?
> 
> The information returned to libxl users is the cache utilization for a 
> certain domain in certain socket, and the main consumers are cloud users like 
> openstack, etc. Of course, we will also provide an xl command to present such 
> information.

To me this doesn't really address the question Ian asked, yet knowing
who's going to be the consumer of the data is also quite relevant for
answering your original question on the method to obtain that data.
Obviously, if the main use of it is per-domain, a domctl would seem like
a suitable approach despite the data being more of sysctl kind. But if
a global view would be more important, that model would seem to make
life needlessly hard for the consumers. In turn, if using a domctl, I tend
to agree that not using shared pages would be preferable; iirc their use
was mainly suggested because of the size of the data.

Jan