IBV_FORK_INIT(3)					  Libibverbs Programmer's Manual					  IBV_FORK_INIT(3)

NAME

       ibv_fork_init - initialize libibverbs to support fork()

SYNOPSIS

       #include <infiniband/verbs.h>

       int ibv_fork_init(void);

DESCRIPTION

       ibv_fork_init()	initializes  libibverbs's  data  structures  to  handle fork() function calls correctly and avoid data corruption, whether
       fork() is called explicitly or implicitly (such as in system()).

       It is not necessary to use this function if all parent process threads are always blocked until all child processes end or  change  address
       spaces via an exec() operation.

RETURN VALUE

       ibv_fork_init() returns 0 on success, or the value of errno on failure (which indicates the failure reason).

NOTES

       ibv_fork_init() 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 has the same effect as calling ibv_fork_init().

       Setting	the  environment  variable  RDMAV_HUGEPAGES_SAFE 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  allo-
       cated 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.

SEE ALSO

       fork(2), wait(2), system(3), exec(3), ibv_get_device_list(3)

AUTHORS

       Dotan Barak <dotanba@gmail.com>

libibverbs							    2006-10-31							  IBV_FORK_INIT(3)