That was grouping domains to directly share scheduling credits, rather than
grouping to share physical resources.
-- Keir
On 10/12/2008 13:21, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
> I remember seeing some post before about domain group scheduler.
> Not sure about its progress now, and maybe you can check that
> thread to see anything useful?
>
> Thanks,
> Kevin
>
>> From:Juergen Gross
>> Sent: Wednesday, December 10, 2008 9:10 PM
>>
>> Hi,
>>
>> Currently the XEN credit scheduler has its pitfalls in
>> supporting weights of
>> domains together with cpu pinning (see the threads
>> http://lists.xensource.com/archives/html/xen-devel/2007-02/msg0
>> 0006.html
>> http://lists.xensource.com/archives/html/xen-devel/2006-10/msg0
>> 0365.html
>> http://lists.xensource.com/archives/html/xen-devel/2007-07/msg0
>> 0303.html
>> which include a rejected patch).
>>
>> We are facing this problem, too. We tried the above patch, but
>> it didn't solve
>> our problem completely, so we decided to start a new solution.
>>
>> Our basic requirement is to limit a set of domains to a set of
>> physical cpus
>> while specifying the scheduling weight for each domain. The
>> general (and in my
>> opinion best) solution would be the introduction of a "pool"
>> concept in XEN.
>>
>> Each physical cpu is dedicated to exactly one pool. At start
>> of XEN this is
>> pool0. A domain is member of a single pool (dom0 will always
>> be member of
>> pool0), there may be several domains in one pool. Scheduling
>> does not cross
>> pool boundaries, so the weight of a domain is only related to
>> the weight of
>> the other domains in the same pool. So it is possible to have
>> an own scheduler
>> for each pool.
>>
>> What changes would be needed?
>> - The hypervisor must be pool-aware. It needs information
>> about the pool
>> configuration (cpu mask, scheduler) and the pool membership
>> of a domain.
>> The scheduler must restrict itself to its own pool only.
>> - There must be an interface to set and query the pool configuration.
>> - At domain creation the domain must be added to a pool.
>> - libxc must be expanded to support the new interfaces.
>> - xend and the xm command must support pools, defaulting to
>> pool0 if no pool
>> is specified
>>
>> The xm commands could look like this:
>> xm pool-create pool1 ncpu=4 # create a pool with 4 cpus
>> xm pool-create pool2 cpu=1,3,5 # create a pool with
>> 3 dedicated cpus
>> xm pool-list # show pools:
>> pool cpus sched domains
>> pool0 0,2,4 credit 0
>> pool1 6-9 credit 1,7
>> pool2 1,3,5 credit 2,3
>> xm pool-modify pool1 ncpu=3 # set new number of cpus
>> xm pool-modify pool1 cpu=6,7,9 # modify cpu-pinning
>> xm pool-destroy pool1 # destroy pool
>> xm create vm5 pool=pool1 # start domain in pool1
>>
>> There is much more potential in this approach:
>> - add memory to a pool? Could be interesting for NUMA
>> - recent discussions on xen-devel related to scheduling
>> (credit scheduler for
>> client virtualization) show some demand for further work
>> regarding priority
>> and/or grouping of domains
>> - this might be an interesting approach for migration of
>> multiple related
>> domains (pool migration)
>> - move (or migrate?) a domain to another pool
>> - ...
>>
>> Any comments, suggestions, work already done, ...?
>> Otherwise we will be starting our effort soon.
>>
>> Juergen
>>
>> --
>> Juergen Gross Principal Developer
>> IP SW OS6 Telephone: +49 (0) 89 636 47950
>> Fujitsu Siemens Computers e-mail:
>> juergen.gross@xxxxxxxxxxxxxxxxxxx
>> Otto-Hahn-Ring 6 Internet: www.fujitsu-siemens.com
>> D-81739 Muenchen Company details:
>> www.fujitsu-siemens.com/imprint.html
>>
>>
>>
>>
>>
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>>
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