Re: [Xen-devel] Xen Platform QoS design discussion

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-04-30 at 16:47 +0000, Xu, Dongxiao wrote:
> domain related QoS data. Here I propose to use the domctl style
> hypercall to get QoS data for specific domain. This has the advantage
> of simplifying the libxl QoS APIs for user-space developers, and also
> make the QoS memory allocation in Xen much easier.

Note that the libxl QoS API need not have any particular resemblance to
the underlying hypercall API, it is perfectly reasonable for libxl (or
libxc even) to massage the data provided by the raw hypercall (or
several hypercalls) into something nicer for end user consumption.

The important thing about any libxl level interface is that the library
API cannot change once it has been introduced, so thought needs to be
given to extensibility and future proofing. The API should also be
structured (so no binary blobs, or arrays of numbers which need special
knowledge to interpret etc).

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)?

Ian.


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel