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dm: block_if: add the io_uring support

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io_uring is a high-performance asynchronous I/O framework, primarily designed
to improve the efficiency of input and output (I/O) operations in user-space
applications.
This patch enables io_uring in block_if module. It utilizes the interfaces
provided by the user-space library `liburing` to interact with io_uring
in kernel-space.

To build the acrn-dm with io_uring support, `liburing-dev` package needs to be
installed. For example, it can be installed like below in Ubuntu 22.04.
        sudo apt install liburing-dev

In order to support both the thread pool mechanism and the io_uring mechanism,
an acrn-dm option `aio` is introduced. By default, thread pool mechanism is
selected.
- Example to use io_uring:
  `add_virtual_device    9 virtio-blk iothread,mq=2,/dev/nvme1n1,writeback,aio=io_uring`
- Example to use thread pool:
  `add_virtual_device    9 virtio-blk iothread,mq=2,/dev/nvme1n1,writeback,aio=threads`
- Example to use thread pool (by default):
  `add_virtual_device    9 virtio-blk iothread,mq=2,/dev/nvme1n1,writeback`

v2 -> v3:
 * Update iothread_handler
    - Use the unified eventfd interfaces to read the counter value of the
      ioeventfd.
    - Remove the while loop to read the ioeventfd. It is not necessary
      because one read would reset the counter value to 0.
 * Update iou_submit_sqe to return an error code
   The caller of iou_submit_sqe shall check the return value.
   If there is NO available submission queue entry in the submission queue,
   need to break the while loop. Request can only be submitted when SQE is
   available.

v1 -> v2:
 * move the logic of reading out ioeventfd from iothread.c to virtio.c, because
   it is specific to the virtqueue handling.

Tracked-On: #8612

Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Acked-by: Wang, Yu1 <yu1.wang@intel.com>
This commit is contained in:
Shiqing Gao
2024-05-28 15:30:13 +08:00
committed by acrnsi-robot
parent edb392e7ed
commit fed8ce513c
4 changed files with 377 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
devicemodel/core/iothread.c
View File

@@ -21,7 +21,7 @@
#define MEVENT_MAX 64
#define MAX_EVENT_NUM 64
struct iothread_ctx {
pthread_t tid;
int epfd;
@@ -35,25 +35,22 @@ io_thread(void *arg)
{
struct epoll_event eventlist[MEVENT_MAX];
struct iothread_mevent *aevp;
int i, n, status;
char buf[MAX_EVENT_NUM];
int i, n;
while(ioctx.started) {
n = epoll_wait(ioctx.epfd, eventlist, MEVENT_MAX, -1);
if (n < 0) {
if (errno == EINTR)
pr_info("%s: exit from epoll_wait\n", __func__);
else
if (errno == EINTR) {
/* EINTR may happen when io_uring fd is monitored, it is harmless. */
continue;
} else {
pr_err("%s: return from epoll wait with errno %d\r\n", __func__, errno);
break;
break;
}
}
for (i = 0; i < n; i++) {
aevp = eventlist[i].data.ptr;
if (aevp && aevp->run) {
/* Mitigate the epoll_wait repeat cycles by reading out the events as more as possible.*/
do {
status = read(aevp->fd, buf, sizeof(buf));
} while (status == MAX_EVENT_NUM);
(*aevp->run)(aevp->arg);
}
}