---
name: "io_uring_set_iowait"
section: "3"
platform: "linux"
package: "liburing"
version: "2.15-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/io_uring_set_iowait"
---

# io\_uring\_set\_iowait(3)

toggle of iowait usage when waiting on CQEs

## NAME

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

## SYNOPSIS

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

**int io\_uring\_set\_iowait(struct io\_uring \****ring***,**                         **bool** *enable\_iowait***);**

## 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)](/io_uring_set_iowait/3.md) 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)](/io_uring_enter/2.md).

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

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

## SEE ALSO

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