Re: [PATCH virtio 0/8] virtio_pci_modern: allow parallel admin queue commands execution

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jun 24, 2024 at 03:09:20PM +0200, Jiri Pirko wrote:
> Mon, Jun 24, 2024 at 01:07:23PM CEST, mst@redhat.com wrote:
> >On Mon, Jun 24, 2024 at 11:04:43AM +0200, Jiri Pirko wrote:
> >> From: Jiri Pirko <jiri@nvidia.com>
> >> 
> >> Currently the admin queue command execution is serialized by a lock.
> >> This patchsets lifts this limitation allowing to execute admin queue
> >> commands in parallel. To do that, admin queue processing needs to be
> >> converted from polling to interrupt based completion.
> >> 
> >> Patches #1-#6 are preparations, making things a bit smoother as well.
> >> Patch #7 implements interrupt based completion for admin queue.
> >> Patch #8 finally removes the admin queue serialization lock.
> >
> >Okay ... I assume this is infrastructure for some other need?
> >I'll review, but I'd like to see this actually used.
> 
> No other need. The currently, admin queue cmds are serialized. Note that
> admin queue is currently created for PF. If you have for example
> multiple VFs in legacy mode reading and writing pci bar, that virtio
> vfio driver translates it into admin queue commands. So for example
> probe on multiple VFs gets serialized. This patchset makes it possible
> to run in parallel.


Well probe is mostly serialized but I think I get what you mean -
I am guessing you mean something else like legacy access commands.
> 
> >
> >
> >> Jiri Pirko (8):
> >>   virtio_pci: push out single vq find code to vp_find_one_vq_msix()
> >>   virtio_pci_modern: treat vp_dev->admin_vq.info.vq pointer as static
> >>   virtio: push out code to vp_avq_index()
> >>   virtio: create admin queues alongside other virtqueues
> >>   virtio_pci_modern: create admin queue of queried size
> >>   virtio_pci_modern: pass cmd as an identification token
> >>   virtio_pci_modern: use completion instead of busy loop to wait on
> >>     admin cmd result
> >>   virtio_pci_modern: remove admin queue serialization lock
> >> 
> >>  drivers/virtio/virtio.c            |  28 +----
> >>  drivers/virtio/virtio_pci_common.c | 109 ++++++++++++++------
> >>  drivers/virtio/virtio_pci_common.h |   9 +-
> >>  drivers/virtio/virtio_pci_modern.c | 160 ++++++++++++-----------------
> >>  include/linux/virtio.h             |   2 +
> >>  include/linux/virtio_config.h      |   2 -
> >>  6 files changed, 150 insertions(+), 160 deletions(-)
> >> 
> >> -- 
> >> 2.45.1
> >