| Message ID | 20231220134755.814917-1-stefanha@redhat.com |
|---|---|
| Headers | show |
| Series | virtio-blk: add iothread-vq-mapping parameter | expand |
Am 20.12.2023 um 14:47 hat Stefan Hajnoczi geschrieben: > 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) Thanks, applied to the block branch. We agreed off-list that the remaining problems can be fixed in follow-up patches. Kevin
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(-)