v4:
- Use DummyVirtioForceArrays naming in QAPI schema [Markus]
v3:
- Rebased onto Kevin's block branch
- Add StringOutputVisitor "<omitted>" patch to fix "info qtree" crash
- Fix QAPI schema formatting [Markus]
- Eliminate unnecessary local variable in get_iothread_vq_mapping_list()
[Markus]
virtio-blk and virtio-scsi devices need a way to specify the mapping between
IOThreads and virtqueues. At the moment all virtqueues are assigned to a single
IOThread or the main loop. This single thread can be a CPU bottleneck, so it is
necessary to allow finer-grained assignment to spread the load. With this
series applied, "pidstat -t 1" shows that guests with -smp 2 or higher are able
to exploit multiple IOThreads.
This series introduces command-line syntax for the new iothread-vq-mapping
property is as follows:
--device
'{"driver":"virtio-blk-pci","iothread-vq-mapping":[{"iothread":"iothread0","vqs":[0,1,2]},...]},...'
IOThreads are specified by name and virtqueues are specified by 0-based
index.
It will be common to simply assign virtqueues round-robin across a set
of IOThreads. A convenient syntax that does not require specifying
individual virtqueue indices is available:
--device
'{"driver":"virtio-blk-pci","iothread-vq-mapping":[{"iothread":"iothread0"},{"iothread":"iothread1"},...]},...'
There is no way to reassign virtqueues at runtime and I expect that to be a
very rare requirement.
Note that JSON --device syntax is required for the iothread-vq-mapping
parameter because it's non-scalar.
Based-on: 81e69329d6a4018f4b37d15b6fc845fbe585a93b
(https://repo.or.cz/qemu/kevin.git block)
Stefan Hajnoczi (4):
qdev-properties: alias all object class properties
string-output-visitor: show structs as "<omitted>"
qdev: add IOThreadVirtQueueMappingList property type
virtio-blk: add iothread-vq-mapping parameter
qapi/virtio.json | 29 +++++
hw/block/dataplane/virtio-blk.h | 3 +
include/hw/qdev-properties-system.h | 5 +
include/hw/virtio/virtio-blk.h | 2 +
include/qapi/string-output-visitor.h | 6 +-
hw/block/dataplane/virtio-blk.c | 155 ++++++++++++++++++++-------
hw/block/virtio-blk.c | 92 +++++++++++++---
hw/core/qdev-properties-system.c | 46 ++++++++
hw/core/qdev-properties.c | 18 ++--
qapi/string-output-visitor.c | 16 +++
10 files changed, 311 insertions(+), 61 deletions(-)
--
2.43.0
