MLOCKALL(2) | System Calls Manual | MLOCKALL(2) |
mlockall
,
munlockall
— lock (unlock)
the address space of a process
#include
<sys/mman.h>
int
mlockall
(int
flags);
int
munlockall
(void);
The
mlockall
()
system call locks into memory the physical pages associated with the address
space of a process until the address space is unlocked, the process exits,
or execs another program image.
The following flags affect the behavior of
mlockall
():
MCL_CURRENT
MCL_FUTURE
Since physical memory is a potentially scarce resource, processes
are limited in how much they can lock down. A single process can lock the
minimum of a system-wide “wired pages” limit and the
per-process RLIMIT_MEMLOCK
resource limit.
The
munlockall
()
call unlocks any locked memory regions in the process address space. Any
regions mapped after an munlockall
() call will not
be locked.
The mlockall
() and
munlockall
() functions return the value 0 if
successful; otherwise the value -1 is returned and the global
variable errno is set to indicate the error.
mlockall
() will fail if:
EINVAL
]ENOMEM
]EAGAIN
]EPERM
]The mlockall
() and
munlockall
() functions conform to
IEEE Std 1003.1-2008 (“POSIX.1”).
The mlockall
() and
munlockall
() functions first appeared in
OpenBSD 2.9.
The per-process resource limit is a limit on the amount of virtual memory locked, while the system-wide limit is for the number of locked physical pages. Hence a process with two distinct locked mappings of the same physical page counts as 2 pages against the per-process limit and only as a single page in the system limit.
December 14, 2014 | OpenBSD-5.9 |