From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: Xen Platform QoS design discussion Date: Fri, 2 May 2014 13:50:41 +0100 Message-ID: <536394A1.6040500@citrix.com> References: <40776A41FC278F40B59438AD47D147A9119F3FEA@SHSMSX104.ccr.corp.intel.com> <1398877340.5166.13.camel@kazak.uk.xensource.com> <40776A41FC278F40B59438AD47D147A9119F42A2@SHSMSX104.ccr.corp.intel.com> <5363804B020000780000E604@mail.emea.novell.com> <40776A41FC278F40B59438AD47D147A9119F4EF4@SHSMSX104.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <40776A41FC278F40B59438AD47D147A9119F4EF4@SHSMSX104.ccr.corp.intel.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Xu, Dongxiao" Cc: Ian Campbell , Jan Beulich , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 02/05/14 13:30, Xu, Dongxiao wrote: >> -----Original Message----- >> From: Jan Beulich [mailto:JBeulich@suse.com] >> Sent: Friday, May 02, 2014 5:24 PM >> To: Xu, Dongxiao >> Cc: Andrew Cooper(andrew.cooper3@citrix.com); Ian Campbell; >> xen-devel@lists.xen.org >> Subject: RE: Xen Platform QoS design discussion >> >>>>> On 01.05.14 at 02:56, 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. > 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. The design of the hypercall has nothing to do with the design of the libxl/XenAPI interface. It is clear from this statement that cloudstack want all information for all domains. Therefore, at one level at least there will be a big set of nested loops like: every $TIMEPERIOD for each domain for each type of information get-$TYPE-information-for-$DOMAIN As far as a XenAPI inteface would go, this would be information coming from the rrdd-daemon. This daemon most certainly wont want to be using a hypercall designed like this. Does anyone know how libvirt/libxl would go about collecting/storing/passing this information? ~Andrew