io\_uring\_set\_iowait(3) liburing Manual io\_uring\_set\_iowait(3)

# [NAME](#NAME)

io\_uring\_set\_iowait - toggle of iowait usage when waiting on CQEs

# [SYNOPSIS](#SYNOPSIS)

```
#include <liburing.h>
```

```
int io_uring_set_iowait(struct io_uring *ring,
                        bool enable_iowait);
```

# [DESCRIPTION](#DESCRIPTION)

By default, io\_uring marks a waiting task as being in iowait if it's sleeping waiting on events and there are pending requests. This isn't necessarily always useful, and may be confusing on non-storage setups where iowait isn't expected. It can also cause extra power usage by preventing the CPU from entering lower sleep states.

The [**io\_uring\_set\_iowait**(3)](/man/os/liburing/io_uring_set_iowait.3) function allows the user to toggle this behavior. If **enable\_iowait** is set to true, the iowait behavior is enabled. If it is set to false, the iowait behavior is disabled. The iowait behavior is enabled by default when a ring is created.

If the iowait is disabled, the submit functions will set **IORING\_ENTER\_NO\_IOWAIT** in the **flags** argument to [**io\_uring\_enter**(2)](/man/os/liburing/io_uring_enter.2).

If the kernel supports this feature, it will be marked by having the **IORING\_FEAT\_NO\_IOWAIT** feature flag set.

Available since kernel 6.15.

# [RETURN VALUE](#RETURN_VALUE)

On success, [**io\_uring\_set\_iowait**(3)](/man/os/liburing/io_uring_set_iowait.3) returns 0. On failure, it returns **-EOPNOTSUPP**.

# [SEE ALSO](#SEE_ALSO)

[**io\_uring\_enter**(2)](/man/os/liburing/io_uring_enter.2), [**io\_uring\_submit**(3)](/man/os/liburing/io_uring_submit.3), [**io\_uring\_submit\_and\_wait**(3)](/man/os/liburing/io_uring_submit_and_wait.3)

July 27, 2025 liburing-2.12

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Document: io_uring_set_iowait(3) from liburing 2.15-r4 (Chainguard OS)
Source: https://github.com/axboe/liburing.git