Linux recently added a new io_uring(7) optimization API that QEMU
doesn't take advantage of yet. The liburing library that QEMU uses
has added a corresponding new API calling io_uring_register_ring_fd().
When this API is called after creating the ring, the io_uring_submit()
library function passes a flag to the io_uring_enter(2) syscall
allowing it to skip the ring file descriptor fdget()/fdput()
operations. This saves some CPU cycles.
Signed-off-by: Sam Li <faithilike...@gmail.com>
---
block/io_uring.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/block/io_uring.c b/block/io_uring.c
index 782afdb433..5247fb79e2 100644
--- a/block/io_uring.c
+++ b/block/io_uring.c
@@ -435,8 +435,16 @@ LuringState *luring_init(Error **errp)
}
ioq_init(&s->io_q);
- return s;
+ if (io_uring_register_ring_fd(&s->ring) < 0) {
+ /*
+ * Only warn about this error: we will fallback to the non-optimized
+ * io_uring operations.
+ */
+ error_reportf_err(*errp,
+ "failed to register linux io_uring ring file
descriptor");
+ }
+ return s;
}
void luring_cleanup(LuringState *s)
--
Use error_reportf_err to avoid memory leak due to not freeing error
object.
--
2.35.1
