io\_uring\_mlock\_size(3) liburing Manual io\_uring\_mlock\_size(3)

# [NAME](#NAME)

io\_uring\_mlock\_size - get required memlock size for a ring

# [SYNOPSIS](#SYNOPSIS)

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

```
ssize_t io_uring_mlock_size(unsigned entries, unsigned flags);
```

# [DESCRIPTION](#DESCRIPTION)

The [**io\_uring\_mlock\_size**(3)](/man/os/liburing/io_uring_mlock_size.3) function returns the required **RLIMIT\_MEMLOCK** memory size for an io\_uring ring with *entries* entries and the specified setup *flags*.

On newer kernels (5.12+), io\_uring no longer requires any memlock memory and this function will return 0. On older kernels (5.11 and prior), this returns the required memory so that the caller can ensure that enough **RLIMIT\_MEMLOCK** space is available before setting up a ring.

For more control over the ring parameters, use [**io\_uring\_mlock\_size\_params**(3)](/man/os/liburing/io_uring_mlock_size_params.3) instead.

# [RETURN VALUE](#RETURN_VALUE)

Returns the required memlock size in bytes on success, 0 if no memlock is needed, or a negative errno value on error.

# [SEE ALSO](#SEE_ALSO)

[**io\_uring\_mlock\_size\_params**(3)](/man/os/liburing/io_uring_mlock_size_params.3), [**io\_uring\_memory\_size**(3)](/man/os/liburing/io_uring_memory_size.3), [**io\_uring\_queue\_init**(3)](/man/os/liburing/io_uring_queue_init.3), [**getrlimit**(2)](/man/os/liburing/getrlimit.2)

January 18, 2025 liburing-2.4

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Document: io_uring_mlock_size(3) from liburing 2.15-r5 (Chainguard OS)
Source: https://github.com/axboe/liburing.git