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From Pawit Pornkitprasan <p.pa...@gmail.com>
Subject Re: PCI-Passthrough with CloudStack
Date Wed, 12 Jun 2013 02:04:48 GMT
On 6/11/13 09:35 PM, "Edison Su" <Edison.su@citrix.com> wrote:

> If change vm's xml is enough, then how about use libvirt's hook system:
> http://www.libvirt.org/hooks.html
> I think, the issue is that, how to let cloudstack only create one VM per KVM host, or
few
> VMs per host(based on the available PCI devices on the host).
> If we think PCI devices are the resource CloudStack should to take care of during the
resource
> allocation, then we need a framework:
> 1. During host discovering, host can report whatever resources it can detect to mgt server.
> RAM/CPU freq/local storage are the resources, that currently supported by kvm agent.
Here
> we may need to add PCI devices as another resource.  Such as, KVM agent host returns
a StartupAuxiliaryDevicesReportCmd
> along as with other startupRouteringcmd/StartStorage*cmd etc, during the startup.
> 2. There will be a listener on the mgt server, which can listen on StartupAuxiliaryDevicesReportCmd,
> then records available PCI devices into DB,  such as host_pci_device_ref table.
> 3. Need to extend FirstFitAllocator, take PCI devices as another resource during the
allocation.
> And also need to find a place to mark the PCI device as used in host_pci_device_ref table,
> so the pci device won't be allocated to more than one VM.
> 4. Have api to create a customized computing offering, the offering can contain info
about
> PCI device, such as how many PCI devices plugged into a VM.
> 5. If user chooses above customized computing offering during the VM deployment, then
the
> allocator in step 3 will be triggered, which will choose a KVM host which has enough
PCI devices
> to fulfill the computing offering.
> 6. In the startupcommand, the mgt server send to kvm host, it should contain the PCI
devices
> allocated to this VM.
> 7. At the KVM agent code, change VM's xml file properly based on the startupcommand.
> How do you think?

I think this is a very good idea. Maybe we can do further
generalization (to support Paul's case) by tagging each PCI device
with a name, and we can store the name inside the compute offering
instead of the ID. Then management will look up inside
host_pci_device_ref and find the ID of a suitable PCI device. This
would allow multiple VMs to be allocated to one host of the host has
multiple PCI cards providing the same function.

> > >
> > > -----Original Message-----
> > > From: Kelven Yang [mailto:kelven.yang@citrix.com]
> > > Sent: 11 June 2013 18:10
> > > To: dev@cloudstack.apache.org
> > > Cc: Ryousei Takano
> > > Subject: Re: PCI-Passthrough with CloudStack
> > >
> > > VirtualMachineTO.params is designed to carry generic VM specific
> > configurations, these configuration parameters can either be statically linked
> > with the VM or dynamically populated based on other factors like this one.
> > Are you passing PCI ID using VirtualMachineTO.params?

I've created PciTO and pass an array similar to VolumeTO and NicTO.
This there anything wrong with this approach?

> > >
> > > Anything that affects VM placement could have impact to HA/migration,
> > we probably need some graceful error-handling in these code paths,
> > hopefully these have been taken care of.
> > >

Migration is prevented by libvirt and cloudstack displays "Failed to
migrate vm" if the user attempts to migrate a VM. I have not
investigated HA yet.

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