On Wed, Aug 16, 2023 at 8:02 AM Si-Wei Liu <si-wei.liu@xxxxxxxxxx> wrote: > > > > On 8/9/2023 8:50 PM, Jason Wang wrote: > > On Wed, Aug 9, 2023 at 8:56 PM Si-Wei Liu <si-wei.liu@xxxxxxxxxx> wrote: > >> Following patchset introduces dedicated group for descriptor table to > >> reduce live migration downtime when passthrough VQ is being switched > >> to shadow VQ. As this RFC set is to seek early feedback on the uAPI > >> and driver API part, for now there's no associated driver patch consuming > >> the API. As soon as the support is in place on both hardware device and > >> driver, performance data will be show using real hardware device. The > >> target goal of this series is to reduce the SVQ switching overhead > >> to less than 300ms on a ~100GB guest with 2 non-mq vhost-vdpa devices. > >> > >> The plan of the intended driver implementation is to use a dedicated > >> group (specifically, 2 in below table) to host descriptor table for > >> all data vqs, different from where buffer addresses are contained (in > >> group 0 as below). cvq does not have to allocate dedicated group for > >> descriptor table, so its buffers and descriptor table would always > >> belong to a same group (1). > > I'm fine with this, but I think we need an implementation in the > > driver (e.g the simulator). > Yes. FWIW for the sake of time saving and get this series accepted > promptly in the upcoming v6.6 merge window, the driver we're going to > support along with this series will be mlx5_vdpa in the formal > submission, and simulator support may come up later after if I got spare > cycle. That would be fine. > Do you foresee any issue without simulator change? No. > We will have > mlx5_vdpa driver consuming the API for sure, that's the target of this > work and it has to be proved working on real device at first. Yes, I mention the simulator just because it's simple, it would be also great if it is proved on real vDPA parent. Thanks > > Thanks, > -Siwei > > > > > Thanks > > > >> > >> | data vq | ctrl vq > >> ==============+==========+=========== > >> vq_group | 0 | 1 > >> vq_desc_group | 2 | 1 > >> > >> > >> --- > >> > >> Si-Wei Liu (3): > >> vdpa: introduce dedicated descriptor group for virtqueue > >> vhost-vdpa: introduce descriptor group backend feature > >> vhost-vdpa: uAPI to get dedicated descriptor group id > >> > >> drivers/vhost/vdpa.c | 27 +++++++++++++++++++++++++++ > >> include/linux/vdpa.h | 11 +++++++++++ > >> include/uapi/linux/vhost.h | 8 ++++++++ > >> include/uapi/linux/vhost_types.h | 5 +++++ > >> 4 files changed, 51 insertions(+) > >> > >> -- > >> 1.8.3.1 > >> > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
