Man Pages

ibv_fork_init(3) - phpMan ibv_fork_init(3) - phpMan

Command: man perldoc info search(apropos)  

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

       ibv_fork_init - initialize libibverbs to support fork()

       #include <infiniband/verbs.h>

       int ibv_fork_init(void);

       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  pro-
       cesses end or change address spaces via an exec() operation.

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

       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

       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 indi-
       rectly 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 work-
       load and usually will not be significant.

       Setting RDMAV_HUGEPAGES_SAFE adds further overhead to all memory registrations.

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

       Dotan Barak <>

libibverbs                        2006-10-31                  IBV_FORK_INIT(3)