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

["Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Friday, May 02, 2014 8:40 PM
> To: Xu, Dongxiao
> Cc: Andrew Cooper(andrew.cooper3@xxxxxxxxxx); Ian Campbell;
> xen-devel@xxxxxxxxxxxxx
> Subject: RE: Xen Platform QoS design discussion
> 
> >>> On 02.05.14 at 14:30, <dongxiao.xu@xxxxxxxxx> wrote:
> >>  -----Original Message-----
> >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> Sent: Friday, May 02, 2014 5:24 PM
> >> To: Xu, Dongxiao
> >> Cc: Andrew Cooper(andrew.cooper3@xxxxxxxxxx); Ian Campbell;
> >> xen-devel@xxxxxxxxxxxxx
> >> Subject: RE: Xen Platform QoS design discussion
> >>
> >> >>> On 01.05.14 at 02:56, <dongxiao.xu@xxxxxxxxx> wrote:
> >> >> From: Ian Campbell [mailto:Ian.Campbell@xxxxxxxxxx]
> >> >> 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.
> >
> > From the discussion with openstack developers, on certain cloud host, all
> > running VM's information (e.g., domain ID) will be stored in a database, and
> > openstack software will use libvirt/XenAPI to query specific domain
> > information. That libvirt/XenAPI API interface basically accepts the domain
> > ID as input parameter and get the domain information, including the platform
> > QoS one.
> >
> > Based on above information, I think we'd better design the QoS hypercall
> > per-domain.
> 
> If you think that this is going to be the only (or at least prevalent)
> usage model, that's probably okay then. But I'm a little puzzled that
> all this effort is just for a single, rather specific consumer. I thought
> that if this is so important to Intel there would be wider interested
> audience.

Not specifically for a single customer.
Currently we consider Openstack a lot because it is one of the most popular 
cloud software.

Thanks,
Dongxiao

> 
> Jan


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