Template: int ibv_fork_init(void)
Input Parameters: None
Output Parameters: None
Return Value: 0 on success, -1 on error. If the call fails, errno will be set to indicate the reason for the failure.
Description: ibv_fork_init initializes libibverbs' data structures to handle the fork() function safely and avoid data corruption, whether fork() is called explicitly or implicitly such as in system() calls.
It is not necessary to call ibv_fork_init if all parent process threads are always blocked until all child processes end or change address space via an exec() operation.
This function works on Linux kernels supporting the MADV_DONTFORK flag for madvise() (2.6.17 and higher).
Setting the environment variable RDMAV_FORK_SAFE or IBV_FORK_SAFE to any value has the same effect as calling ibv_fork_init().
Setting the environment variable RDMAV_HUGEPAGES_SAFE to any value tells the library to check the underlying page size used by the kernel for memory regions. This is required if an application uses huge pages either directly or indirectly via a library such as libhugetlbfs.
Calling ibv_fork_init() will reduce performance due to an extra system call for every memory registration, and the additional memory allocated to track memory regions. The precise performance impact depends on the workload and usually will not be significant.
Setting RDMAV_HUGEPAGES_SAFE adds further overhead to all memory registrations.