Prior to this patch, one single iothread instance is created and initialized
in the `main` function. This single iothread monitors all the registered fds
and handles all the corresponding requests. It leads to the limited flexibility
of the iothread support.
To improve the flexibility of the iothread support, this patch does:
- add the support of multiple iothread instances.
`iothread_create` is introduced to create a certain number of iothread
instances. It shall be called at first by each virtual device owner (such as
virtio-blk BE) on initialization phase. Then, `iothread_add` can be called
to add the to be monitored fd to the specified iothread.
- update virtio-blk BE to let the acrn-dm option `iothread` accept a number
as the number of iothread instances to be created.
If `iothread` is contained in the parameters, but the number is not specified,
one iothread instance would be created by default.
Examples to specify the number of iothread instances:
1. Create 2 iothread instances
`add_virtual_device 9 virtio-blk iothread=2,mq=2,/dev/nvme1n1,writeback,aio=io_uring`
2. Create 1 iothread instances (by default)
`add_virtual_device 9 virtio-blk iothread,mq=2,/dev/nvme1n1,writeback,aio=io_uring`
- update virtio-blk BE to separate the request handling of different virtqueues
to different iothreads.
The request from one or more virtqueues can be handled in one iothread.
The mapping between virtqueues and iothreads is based on round robin.
v1 -> v2:
* add a mutex to protect the free ioctx slot allocation
Tracked-On: #8612
Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Acked-by: Wang, Yu1 <yu1.wang@intel.com>
7e6a239646