mlockall(2) [netbsd man page]

MLOCKALL(2)						      BSD System Calls Manual						       MLOCKALL(2)

NAME

     mlockall, munlockall -- lock (unlock) the address space of a process

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/mman.h>

     int
     mlockall(int flags);

     int
     munlockall(void);

DESCRIPTION

     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  Lock all pages currently mapped into the process's address space.

     MCL_FUTURE   Lock all pages mapped into the process's address space in the future, at the time the mapping is established.  Note that this
		  may cause future mappings to fail if those mappings cause resource limits to be exceeded.

     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.

RETURN VALUES

     A return value of 0 indicates that the call succeeded and all pages in the range have either been locked or unlocked.  A return value of -1
     indicates an error occurred and the locked status of all pages in the range remains unchanged.  In this case, the global location errno is
     set to indicate the error.

ERRORS

     mlockall() will fail if:

     [EINVAL]		The flags argument is zero, or includes unimplemented flags.

     [ENOMEM]		Locking the indicated range would exceed either the system or per-process limit for locked memory.

     [EAGAIN]		Some or all of the memory mapped into the process's address space could not be locked when the call was made.

     [EPERM]		The calling process does not have the appropriate privilege to perform the requested operation.

SEE ALSO

     mincore(2), mlock(2), mmap(2), munmap(2), setrlimit(2)

STANDARDS

     The mlockall() and munlockall() functions conform to IEEE Std 1003.1b-1993 (``POSIX.1'').

HISTORY

     The mlockall() and munlockall() functions first appeared in NetBSD 1.5.

BUGS

     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 as only a single page in the system limit.

BSD
								   June 12, 1999							       BSD

MLOCKALL(P)						     POSIX Programmer's Manual						       MLOCKALL(P)

NAME

       mlockall, munlockall - lock/unlock the address space of a process (REALTIME)

SYNOPSIS

       #include <sys/mman.h>

       int mlockall(int flags);
       int munlockall(void);

DESCRIPTION

       The mlockall() function shall cause all of the pages mapped by the address space of a process to be memory-resident until unlocked or until
       the process exits or execs another process image. The flags argument determines whether the pages to be locked are those  currently  mapped
       by  the	address  space	of  the process, those that are mapped in the future, or both. The flags argument is constructed from the bitwise-
       inclusive OR of one or more of the following symbolic constants, defined in <sys/mman.h>:

       MCL_CURRENT
	      Lock all of the pages currently mapped into the address space of the process.

       MCL_FUTURE
	      Lock all of the pages that become mapped into the address space of the process in the future, when those mappings are established.

       If MCL_FUTURE is specified, and the automatic locking of future mappings eventually causes the amount of locked memory to exceed the amount
       of  available  physical	memory	or any other implementation-defined limit, the behavior is implementation-defined. The manner in which the
       implementation informs the application of these situations is also implementation-defined.

       The munlockall() function shall unlock all currently mapped pages of the address space of the process. Any pages that  become  mapped  into
       the address space of the process after a call to munlockall() shall not be locked, unless there is an intervening call to mlockall() speci-
       fying MCL_FUTURE or a subsequent call to mlockall() specifying MCL_CURRENT. If pages mapped into the address space of the process are  also
       mapped  into the address spaces of other processes and are locked by those processes, the locks established by the other processes shall be
       unaffected by a call by this process to munlockall().

       Upon successful return from the mlockall() function that specifies MCL_CURRENT, all currently mapped pages of the  process'  address  space
       shall  be  memory-resident and locked. Upon return from the munlockall() function, all currently mapped pages of the process' address space
       shall be unlocked with respect to the process' address space. The memory residency of unlocked pages is unspecified.

       The appropriate privilege is required to lock process memory with mlockall().

RETURN VALUE

       Upon successful completion, the mlockall() function shall return a value of zero. Otherwise, no additional memory shall be locked, and  the
       function  shall	return a value of -1 and set errno to indicate the error. The effect of failure of mlockall() on previously existing locks
       in the address space is unspecified.

       If it is supported by the implementation, the munlockall() function shall always return a value of  zero.  Otherwise,  the  function  shall
       return a value of -1 and set errno to indicate the error.

ERRORS

       The mlockall() function shall fail if:

       EAGAIN Some or all of the memory identified by the operation could not be locked when the call was made.

       EINVAL The flags argument is zero, or includes unimplemented flags.

       The mlockall() function may fail if:

       ENOMEM Locking  all of the pages currently mapped into the address space of the process would exceed an implementation-defined limit on the
	      amount of memory that the process may lock.

       EPERM  The calling process does not have the appropriate privilege to perform the requested operation.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       exec() , exit() , fork() , mlock() , munmap() , the Base Definitions volume of IEEE Std 1003.1-2001, <sys/mman.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							       MLOCKALL(P)