On Thu, Jul 26, 2018 at 05:30:07PM +0200, Cornelia Huck wrote: > On Thu, 26 Jul 2018 15:50:28 +0200 > Erik Skultety <eskultet@xxxxxxxxxx> wrote: > > > On Tue, Jul 24, 2018 at 11:44:40AM -0600, Alex Williamson wrote: > > > On Fri, 20 Jul 2018 10:19:24 +0800 > > > Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx> wrote: > > > > > > > Current mdev device create interface depends on fixed mdev type, which get uuid > > > > from user to create instance of mdev device. If user wants to use customized > > > > number of resource for mdev device, then only can create new mdev type for that > > > > which may not be flexible. This requirement comes not only from to be able to > > > > allocate flexible resources for KVMGT, but also from Intel scalable IO > > > > virtualization which would use vfio/mdev to be able to allocate arbitrary > > > > resources on mdev instance. More info on [1] [2] [3]. > > > > > > > > To allow to create user defined resources for mdev, it trys to extend mdev > > > > create interface by adding new "instances=xxx" parameter following uuid, for > > > > target mdev type if aggregation is supported, it can create new mdev device > > > > which contains resources combined by number of instances, e.g > > > > > > > > echo "<uuid>,instances=10" > create > > > > > > > > VM manager e.g libvirt can check mdev type with "aggregation" attribute which > > > > can support this setting. If no "aggregation" attribute found for mdev type, > > > > previous behavior is still kept for one instance allocation. And new sysfs > > > > attribute "instances" is created for each mdev device to show allocated number. > > > > > > > > This trys to create new KVMGT type with minimal vGPU resources which can be > > > > combined with "instances=x" setting to allocate for user wanted resources. > > > > > > "instances" makes me think this is arg helps to create multiple mdev > > > instances rather than consuming multiple instances for a single mdev. > > > You're already exposing the "aggregation" attribute, so doesn't > > > "aggregate" perhaps make more sense as the create option? We're asking > > > the driver to aggregate $NUM instances into a single mdev. The mdev > > > attribute should then perhaps also be "aggregated_instances". > > I agree, that seems like a better naming scheme. > > (...) > > > > I'm curious what libvirt folks and Kirti think of this, it looks like > > > it has a nice degree of backwards compatibility, both in the sysfs > > > interface and the vendor driver interface. Thanks, > > > > Since libvirt doesn't have an API to create mdevs yet, this doesn't pose an > > issue for us at the moment. I see this adds new optional sysfs attributes which > > we could expose within our device capabilities XML, provided it doesn't use a > > free form text, like the description attribute does. > > One thing I noticed is that we have seem to have an optional (?) > vendor-driver created "aggregation" attribute (which always prints > "true" in the Intel driver). Would it be better or worse for libvirt if > it contained some kind of upper boundary or so? Additionally, would it Can you be more specific? Although, I wouldn't argue against data that conveys some information, since I would treat the mere presence of the optional attribute as a supported feature that we can expose. Therefore, additional *structured* data which sets clear limits to a certain feature is only a plus that we can expose to the users/management layer. > be easier if the "create" attribute always accepted > ",instances=1" (calling the .create ops in that case?) Is ^this libvirt related question? If so, then by accepting such syntax you'll definitely save us a few lines of code ;). However, until we have a clear vision on how to tackle the mdev migration, I'd like to avoid proposing a libvirt "create" API until then. Erik
