Re: [pve-devel] [PATCH common/qemu-server/manager] improve vGPU (mdev) usage for NVIDIA

["DERUMIER, Alexandre" <Alexandre.DERUMIER@groupe-cyllene.com>]

Le 9/08/22 à 10:39, Dominik Csapak a écrit :
> On 8/9/22 09:59, DERUMIER, Alexandre wrote:
>> Le 26/07/22 à 08:55, Dominik Csapak a écrit :
>>> so maybe someone can look at that and give some feedback?
>>> my idea there would be to allow multiple device mappings per node
>>> (instead of one only) and the qemu code would select one automatically
>> Hi Dominik,
>>
>> do you want to create some kind of pool of pci devices in your ""add 
>> cluster-wide hardware device mapping" patches series ?
>>
>> Maybe in hardwaremap, allow to define multiple pci address on same node ?
>>
>> Then, for mdev, look if a mdev already exist in 1 of the device.
>> If not, try to create the mdev if 1 device, if it's failing (max 
>> number of mdev reached), try to create mdev on the other device,...
>>
>> if not mdev, choose a pci device in the pool not yet detached from host.
>>
> 
> yes i plan to do this in my next iteration of the mapping series
> (basically what you describe)
Hi, sorry to be late.


> my (rough) idea:
> 
> have a list of pci paths in mapping (e.g. 01:00.0;01:00.4;...)
> (should be enough, i don't think grouping unrelated devices (different 
> vendor/product) makes much sense?)
yes, that's enough for me. we don't want to mix unrelated devices.

BTW, I'm finally able to do live migration with nvidia mdev vgpu. (need 
to compile the nvidia vfio driver with an option to enable it + add
"-device vfio-pci,x-enable-migration=on,..."

So, maybe adding a "livemigrate" flag on the hardwaremap could be great :)

Could be usefull for stateless usb device, like usb dongle,where we 
could unplug usb/livemigrate/replug usb.



> 
> * non mdev:
>    qemu-server checks the pci reservations (which we already have)
>    and takes the first not yet reserved path
> 
> * mdev
>    qemu-server iterates over the devices until it finds one
>    with the given mdev type available
> 
> if none is found, error out
> seem great :)