The ASYNC flag forces requests to go to worker threads. Worker threads
are expensive. Let the kernel decide what to do.
With this change, I no longer see an excessive amount of io_uring worker
threads.
Quote from the manual for io_uring_sqe_set_flags(3):
```
IOSQE_ASYNC
Normal operation for io_uring is to try and issue an sqe
as non-blocking first, and if that fails, execute it in an
async manner. To support more efficient overlapped
operation of requests that the application knows/assumes
will always (or most of the time) block, the application
can ask for an sqe to be issued async from the start. Note
that this flag immediately causes the SQE to be offloaded
to an async helper thread with no initial non-blocking
attempt. This may be less efficient and should not be
used liberally or without understanding the performance
and efficiency tradeoffs.
```
Signed-off-by: Wei Liu <liuwe@microsoft.com>
Instead of silently ignoring the error, return an error to the callers.
This in practice should never happen, because the submission queue size
(ring depth) is the same as the virtio queue size. Virtio queue won't
push more requests than there are submission queue entries.
Signed-off-by: Wei Liu <liuwe@microsoft.com>
Historically the Cloud Hypervisor coding style has been to ensure that
all imports are ordered and placed in a single group. Unfortunately
cargo fmt has no support for ensuring that all imports are in a single
group so if whitespace lines were added as part of the import statements
then they would only be odered correctly in the group.
By adopting "group_imports="StdExternalCrate" we can enforce a style
where imports are placed in at most three groups for std, external
crates and the crate itself. Choosing a style enforceable by the tooling
reduces the reviewer burden.
Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
It doens't make sense to limit this to the async_io module and import
across modules so place in default create module.
Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
warning: this argument is a mutable reference, but not used mutably
--> block/src/async_io.rs:68:28
|
68 | fn query_block_size(f: &mut File, block_size_type: BlockSize) -> std::io::Result<u64> {
| ^^^^^^^^^ help: consider changing to: `&File`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_pass_by_ref_mut
Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
This commit merges crates `qcow`, `vhdx` and `block_util` into the
crate `block`, which can allow `qcow` to use functions from `block_util`
without introducing a circular crate dependency.
This commit is based on crosvm implementation:
f2eecc4152
Signed-off-by: Yu Li <liyu.yukiteru@bytedance.com>
