Use of O_DIRECT flag could be a performance option.
But this flag may impose alignment restrictions on the length
and address of user-space buffers and the file offset of I/Os.
To support the use of O_DIRECT flag in block_if, this patch adds the support
to handle the misaligned request.
- When O_DIRECT flag is used (`nocache` is specified in acrn-dm parameters),
* if the original I/O request is aligned,
the original I/O request is submitted directly.
* if the original I/O request is not aligned (either due to the buffer
address/length misalignment, or the offset misalignment),
the misaligned request is converted to an aligned request before
submission.
- When O_DIRECT flag is not used,
the original I/O request is submitted directly.
v1 -> v2:
* cleanup the free() logic in `blockif_init_bounced_write`
Tracked-On: #8612
Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Acked-by: Wang, Yu1 <yu1.wang@intel.com>
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>
block_if is the backend of ahci and virtio-blk. Only one queue is
supported by block_if now. Several worker threads are created as
the thread pool for the queue. One BIG mutex is used for the queue
and thread operation. With this patch block_if can support multiple
queues and each queue is backed by several worker threads. blockif_req
can be submited/enqueued into one specified queue. By spliting into
several queues contention from the BIG mutex can be relieved/eliminated.
This is used to support virtio-blk multiple queues feature.
Tracked-On: #8612
Signed-off-by: Jian Jun Chen <jian.jun.chen@intel.com>
Acked-by: Wang, Yu1 <yu1.wang@intel.com>
Virtio-blk can support multiple virtqueues (mq) which is negotiated
between FE and BE by the feature bit VIRTIO_BLK_F_MQ. The virtqueue
number of virtio-blk can be specified by "mq=x" in the parameter.
For example: "virtio-blk,iothread,mq=2,..."
Tracked-On: #8612
Signed-off-by: Jian Jun Chen <jian.jun.chen@intel.com>
Acked-by: Wang, Yu1 <yu1.wang@intel.com>
It is found that windows will issue blkio operation with amount of
sectors in one request. This patch extends the max iov number of
virtio block to 256.
Tracked-On: #2962
Signed-off-by: Yu Wang <yu1.wang@intel.com>
Acked-by: Yin Fengwei <fengwei.yin@intel.com>
Support DISCARD command is meaningful when eMMC usage is high or
there are lots of remove operations. For example, when Guest
Android is running, there will be lots of files being created and
removed. However, virtio-blk BE does not support DISCARD command,
data remove operation in UOS will not trigger erase in eMMC. After
period of time, the eMMC will be consumed out, and erase must be
done by eMMC firmware before writing any new data. This causes the
eMMC performance decrease in the whole system (SOS and UOS).
To solve the problem, DISCARD should be supported in virtio-blk BE.
Tracked-On: #2011
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Reviewed-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
To keep consistent with kernal code, change delete to discard.
Tracked-On: #2011
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Reviewed-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
1. support "writeback" and "writethru" mode toggling for virtio-blk
conditionally. When starting DM with "writethru" parameter in
virtio-blk, guest OS could not toggle cache mode. When starting DM
with "writeback" parameter in virtio-blk, guest OS could toggle
cache mode.
------------------------------
DM cmdline | toggle support
------------+-----------------
writeback | yes
writethru | no
------------------------------
2. To toggle cache mode, run below command in guest OS:
echo "write back" > /sys/devices/xxx/vdx/cache_type
OR
echo "write through" > /sys/devices/xxx/vdx/cache_type
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Reviewed-by: Shuo Liu <shuo.a.liu@intel.com>
Acked-by: Yin Fengwei <fengwei.yin@intel.com>
