[Qemu-devel] [RFC PATCH 0/2] qemu: ioeventfd for virtio-ccw.

[Cornelia Huck]

This patch series makes use of the s390 ioeventfd implementation
to speed up virtio-ccw a bit.

We hook up virtio notifications via diagnose 500 as ioeventfds,
specifying a subchannel id and virtqueue index combination.

ioeventfds are used by default for all virtio devices; there's
an ioeventfd property that can be used to turn ioeventfd usage
off for a device (similar to virtio-pci).

A simple dd on a virtio-blk device
   dd if=/dev/vda of=/dev/null iflag=direct bs=4k count=10000
is now twice as fast :)

(Patches are against master.)

Cornelia Huck (2):
  linux-headers: Update with ioeventfd changes.
  virtio-ccw: Wire up ioeventfd.

 hw/s390x/css.c            |   2 +-
 hw/s390x/css.h            |   1 +
 hw/s390x/virtio-ccw.c     | 114 ++++++++++++++++++++++++++++++++++++++++++++++
 hw/s390x/virtio-ccw.h     |   7 +++
 linux-headers/linux/kvm.h |   4 +-
 target-s390x/cpu.h        |  16 +++++++
 target-s390x/kvm.c        |  27 +++++++++++
 7 files changed, 169 insertions(+), 2 deletions(-)

-- 
1.7.12.4