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 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.

SEE ALSO

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

AUTHORS

       Dotan Barak <dotanba@gmail.com>