[PATCH v3 0/4] irqfd, iothread and polling support

[Jinhao Fan]

This series of performance enhancements brings iothread and polling
capabilities to qemu-nvme. The first two patches implements support
for irqfd, which solves thread safety problems for interrupt emulation
outside the main loop thread. The third patch adds support for
emulating NVMe IO queues in a dedicated iothread, which avoid
interference from other devices running on the main loop thread.
The fourth patch implements SQ and CQ pollers, thus enabling polling
on SQ and CQ.

After all these optimizations, our performance becomes similar to
virtio-blk.

Comparison (KIOPS):

QD                    1   4  16  64
virtio-blk           59 185 260 256
nvme                 53 155 245 309
virtio-blk-polling   88 212 210 213
nvme-polling        123 165 189 191

Changes since v2:
 - Add polling support
 - Do not set up MSI-X masking handlers when irq-eventfd is off

Changes since v1:
 - Avoid duplicate initilization of cq timer

Jinhao Fan (4):
  hw/nvme: support irq(de)assertion with eventfd
  hw/nvme: use KVM irqfd when available
  hw/nvme: add iothread support
  hw/nvme: add polling support

 hw/nvme/ctrl.c       | 394 ++++++++++++++++++++++++++++++++++++++++---
 hw/nvme/ns.c         |  21 ++-
 hw/nvme/nvme.h       |  13 +-
 hw/nvme/trace-events |   3 +
 4 files changed, 401 insertions(+), 30 deletions(-)

-- 
2.25.1