[openstack-dev] Some idea on device assignment support

John Garbutt John.Garbutt at citrix.com
Tue Nov 6 16:07:52 UTC 2012


Hi,

It would be good to join in, at Citrix we are looking at:
https://blueprints.launchpad.net/nova/+spec/xenapi-gpu-passthrough

Two quick questions:

1) What are the use cases for the more general pass-through?
I understand the "want GPU flavour" concept, for desktops or HPC workloads.
Is the idea for higher performance do the device pass-through?
Would the extra spec try to say: "high performance local disk"?

2) What about unifying Memory, CPU, GPU, Disks et al?
I see this are all "consumable resources" with configurable/optional "over -commit".
Clearly this is data the scheduler needs to collect and make its decisions on.
I haven't look how that looks in the DB, but it seems worth sharing filters and reporting.
I guess this has knock-on issues with Ceilometer and friends.

Thanks,
John

-----Original Message-----
From: Vladimir Popovski [mailto:vladimir at zadarastorage.com] 
Sent: 01 November 2012 7:30 PM
To: Vishvananda Ishaya; OpenStack Development Mailing List
Subject: Re: [openstack-dev] Some idea on device assignment support

Hi All,

In next couple of days we will resume our PCI passthrough/SR-IOV proposal.
With the help from Cisco folks I'm sure we will be able to propose it pretty soon.

I suppose that on the first stage it might be enough to use instance_types's extra specs to specify what exactly should be assigned to the instance. I don't think that cloud users should have a control about what and when should be attached (for sure not physical USBs). IMHO, having special instance types (like with X PCI devices of type Y or with GPU, etc) will be enough.

We can easily propagate information about device availability to the scheduler and on scheduler level to make a decision about proper host.

Regarding querying HW resources - we implemented it on host settings level. Of course we can add something on virt driver level, but it will be quite different per each installation type.

Regards,
-Vladimir


-----Original Message-----
From: Vishvananda Ishaya [mailto:vishvananda at gmail.com]
Sent: Thursday, November 01, 2012 11:22 AM
To: OpenStack Development Mailing List
Cc: Ian Wells; vladimir at zadarastorage.com
Subject: Re: [openstack-dev] Some idea on device assignment support


On Nov 1, 2012, at 8:39 AM, heut2008 <heut2008 at gmail.com> wrote:

>
> should  we create  a new table to  manage all these  devices? or  each 
> nova-compute node manage their own devices allocation,if there is no 
> new table to record this.  we need each kind of passthrough  devices 
> has a driver to keep track of how many resources is free and how many 
> is in use,  these info  is updated to schedule  by sending capability 
> info periodly.

I would prefer to avoid adding new tables unless we have to. It seems like the HostState class in host_manager needs to be able to support arbitrary keys for counting resources. Then we could create filter and weighting functions based on these arbitrary keys and update the consume method to consume resources from these keys based on instance_type_extra_specs.

Perhaps we need some kind of compute_metadata. there is a compute stats table which we might be able to abuse for this purpose.

Vish

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