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

Cornelia Huck
2013-02-21T13:13:10Z

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(-)

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1.7.12.4