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>