Re: [Qemu-devel] [PATCH V7 00/16] Support more virtio queues

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

On Thu, Apr 23, 2015 at 02:21:33PM +0800, Jason Wang wrote:
> We current limit the max virtio queues to 64. This is not sufficient
> to support multiqueue devices (e.g recent Linux support up to 256
> tap queues). So this series tries to let virtio to support more
> queues.

I put some of these in my tree.
Pls check it out to make sure I didn't make mistakes,
and send patches on top.


> No much works need to be done except:
> 
> - Introducing transport specific queue limitation. This is used to
>   simplify increasing the limitation for one transport without
>   harming the rest.
> - Let each virtio transport to use specific limit.
> - Speedup the MSI-X masking and unmasking through per vector queue
>   list, and increase the maximum MSI-X vectors supported by qemu.
> - With the above enhancements, increase the maximum number of
>   virtqueues supported by PCI from 64 to 1024.
> - Compat legacy virtio queue limit
> 
> With this patch, we can support up to 256 queues. Since x86 can only
> allow about 240 interrupt vectors for MSI-X, current Linux driver can
> only have about 80 queue pairs has their private MSI-X interrupt
> vectors. With sharing IRQ with queue pairs (RFC posted in
> https://lkml.org/lkml/2014/12/25/169), Linux driver can have up
> to about 186 queue pairs has their private MSI-X interrupt vectors.
> 
> Stress/migration test on virtio-pci, compile test on other
> targets. And make check on s390x-softmmu and ppc64-softmmu.
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Richard Henderson <rth@twiddle.net>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Alexander Graf <agraf@suse.de>
> Cc: Keith Busch <keith.busch@intel.com>
> Cc: Kevin Wolf <kwolf@redhat.com>
> Cc: Stefan Hajnoczi <stefanha@redhat.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
> Cc: Amit Shah <amit.shah@redhat.com>
> Cc: qemu-ppc@nongnu.org
> 
> Please review
> 
> Thanks
> 
> Changes from V6:
> - Tweak some commit logs
> - Replace the missed VIRTIO_PCI_MAX in ccw with a bus specific limit
> - Bump the pci queue limit from 513 to 1024
> 
> Changes from V5:
> - Rebase to HEAD
> - Drop the patch that introduce helper to get vq index since there has
>   already one
> - Don't try to solve the migration compatibility issue for invalid
>   configuration like vectors > 128 with only 64 virto queues. This is
>   done by let msix calaucalte the correct bar size and drop the patch
>   18 that intrdouces the auto_msix_bar_size.
> - Cleanup the bar size and pba offset calcuation code
> - Add a comment to explain the new virtio pci queue limit number 513
> 
> Changes from V4:
> - Drop the patch of bus limitation validation and send it as an
>   independent patch
> - Don't let the virtio-pci to calculate the MSI-X bar size, instead,
>   tell the msix code whether or not to use legacy bar size and let it
>   to do this
> - Make sure the MSI-X bar size is at least 4K
> - Subject typos fixes for patch 8
> - Mention adapter routes changes in the commit log of patch 9
> - Only use the vector to queue list for virtio-pci to avoid the
>   unnecessary possible overhead on other transport.
> 
> Changes from V3:
> - rebase to master and target to 2.4
> - handling compat issues for spapr
> - fixes for hmp command completion when we have a nic with 256 queues
> - using VIRTIO_NO_VECTOR instead of 0 for invalid virtqueue in
>   virtio-ccw
> - fix compile issues for ppc64-softmmu
> - don't export VIRTIO_CCW_QUEUE_MAX by introducing a gsi limit and
>   inherit in ccw
> - use transport specific queue limit in virtio-serial
> - correct the stale comment for AdapterRoutes and move it to ccw patch
> - replace 128 with queue_max + 64 and add a comment for this in
>   virtio_ccw_notify()
> 
> Changes from V2:
> - move transport specific limitation to their implementation. (The
>   left is VIRTIO_CCW_QUEUE_MAX since I fail to find a common header
>   files other than virtio.h)
> - use virtio_get_queue_ma) if possible in virtio.c
> - AdapterRoutes should use ccw limit
> - introduce a vector to queue mapping for virito devices and speedup
>   the MSI-X masking and unmasking through this.
> 
> Changes from V1:
> - add a validation against the bus limitation
> - switch to use a bus specific queue limit instead of a global one,
>   this will allow us to just increase the limit of one transport
>   without disturbing others.
> - only increase the queue limit of virtio-pci
> - limit the maximum number of virtio queues to 64 for legacy machine
>   types
> 
> Jason Wang (16):
>   virtio-net: fix the upper bound when trying to delete queues
>   pc: add 2.4 machine types
>   spapr: add machine type specific instance init function
>   ppc: spapr: add 2.4 machine type
>   monitor: replace the magic number 255 with MAX_QUEUE_NUM
>   monitor: check return value of qemu_find_net_clients_except()
>   virtio-ccw: using VIRTIO_NO_VECTOR instead of 0 for invalid virtqueue
>   virtio: introduce bus specific queue limit
>   virtio-ccw: introduce ccw specific queue limit
>   virtio-s390: switch to bus specific queue limit
>   virtio-mmio: switch to bus specific queue limit
>   virtio-pci: switch to use bus specific queue limit
>   virtio: introduce vector to virtqueues mapping
>   virtio-pci: speedup MSI-X masking and unmasking
>   virtio-pci: increase the maximum number of virtqueues to 513
>   pci: remove hard-coded bar size in msix_init_exclusive_bar()
> 
>  hw/char/virtio-serial-bus.c    |  2 +-
>  hw/i386/pc_piix.c              | 34 ++++++++++++++++---
>  hw/i386/pc_q35.c               | 31 ++++++++++++++++--
>  hw/net/virtio-net.c            |  6 ++--
>  hw/pci/msix.c                  | 30 ++++++++++-------
>  hw/ppc/spapr.c                 | 59 +++++++++++++++++++++++++++++++--
>  hw/s390x/s390-virtio-bus.c     |  7 ++--
>  hw/s390x/s390-virtio-ccw.c     |  7 ++--
>  hw/s390x/virtio-ccw.c          | 22 ++++++++-----
>  hw/scsi/virtio-scsi.c          |  4 +--
>  hw/virtio/virtio-mmio.c        |  7 ++--
>  hw/virtio/virtio-pci.c         | 65 +++++++++++++++++++++++--------------
>  hw/virtio/virtio.c             | 74 +++++++++++++++++++++++++++++++++---------
>  include/hw/s390x/s390_flic.h   |  4 ++-
>  include/hw/virtio/virtio-bus.h |  2 ++
>  include/hw/virtio/virtio.h     |  6 ++--
>  monitor.c                      | 25 +++++++-------
>  17 files changed, 291 insertions(+), 94 deletions(-)
> 
> -- 
> 2.1.0