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Re: [Qemu-devel] [PATCH 0/9] virtio-blk: multiqueue support
From: |
Christian Borntraeger |
Subject: |
Re: [Qemu-devel] [PATCH 0/9] virtio-blk: multiqueue support |
Date: |
Tue, 24 May 2016 14:51:04 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 |
On 05/21/2016 01:40 AM, Stefan Hajnoczi wrote:
> The virtio_blk guest driver has supported multiple virtqueues since Linux
> 3.17.
> This patch series adds multiple virtqueues to QEMU's virtio-blk emulated
> device.
>
> Ming Lei sent patches previously but these were not merged. This series
> implements virtio-blk multiqueue for QEMU from scratch since the codebase has
> changed. Live migration support for s->rq was also missing from the previous
> series and has been added.
>
> It's important to note that QEMU's block layer does not support multiqueue
> yet.
> Therefore virtio-blk device processes all virtqueues in the same AioContext
> (IOThread). Further work is necessary to take advantage of multiqueue support
> in QEMU's block layer once it becomes available.
>
> I will post performance results once they are ready.
>
> Stefan Hajnoczi (9):
> virtio-blk: use batch notify in non-dataplane case
> virtio-blk: tell dataplane which vq to notify
> virtio-blk: associate request with a virtqueue
> virtio-blk: add VirtIOBlockConf->num_queues
> virtio-blk: multiqueue batch notify
> vmstate: add VMSTATE_VARRAY_UINT32_ALLOC
> virtio-blk: live migrate s->rq with multiqueue
> virtio-blk: dataplane multiqueue support
> virtio-blk: add num-queues device property
>
> hw/block/dataplane/virtio-blk.c | 68 +++++++-------
> hw/block/dataplane/virtio-blk.h | 2 +-
> hw/block/virtio-blk.c | 200
> ++++++++++++++++++++++++++++++++++++----
> include/hw/virtio/virtio-blk.h | 13 ++-
> include/migration/vmstate.h | 10 ++
> 5 files changed, 241 insertions(+), 52 deletions(-)
>
With 2.6 I see 2 host threads consuming a CPU when running fio in a single CPU
guest with a null-blk device and iothread for that disk. (the vcpu thread and
the iothread). With this patchset the main thread also consumes almost 80% of a
CPU doing polling in main_loop_wait. I have not even changes the num-queues
values.
So in essence 3 vs 2 host cpus.
Christian
- Re: [Qemu-devel] [PATCH 5/9] virtio-blk: multiqueue batch notify, (continued)
[Qemu-devel] [PATCH 4/9] virtio-blk: add VirtIOBlockConf->num_queues, Stefan Hajnoczi, 2016/05/20
[Qemu-devel] [PATCH 6/9] vmstate: add VMSTATE_VARRAY_UINT32_ALLOC, Stefan Hajnoczi, 2016/05/20
[Qemu-devel] [PATCH 7/9] virtio-blk: live migrate s->rq with multiqueue, Stefan Hajnoczi, 2016/05/20
[Qemu-devel] [PATCH 9/9] virtio-blk: add num-queues device property, Stefan Hajnoczi, 2016/05/20
[Qemu-devel] [PATCH 8/9] virtio-blk: dataplane multiqueue support, Stefan Hajnoczi, 2016/05/20
Re: [Qemu-devel] [PATCH 0/9] virtio-blk: multiqueue support,
Christian Borntraeger <=
[Qemu-devel] [RFC] virtio-blk: simple multithreaded MQ implementation for bdrv_raw, Roman Pen, 2016/05/27