mlockall(3)						     Library Functions Manual						       mlockall(3)

NAME

       mlockall, munlockall - Locks into memory, or unlocks, all of a specified process's pages (P1003.1b)

LIBRARY

       Realtime Library (librt.so, librt.a)

SYNOPSIS

       #include <sys/mman.h>

       int mlockall (
       int flags);

       int munlockall (void);

PARAMETERS

       flags   Determines  whether  the pages to be locked are those currently mapped by the process's address space, those that will be mapped in
	       the future, or both. The flags argument is constructed as the OR of one or more of the constants,  MCL_CURRENT  or  MCL_FUTURE,	as
	       defined in the <mman.h> header file.

DESCRIPTION

       The  mlockall  function causes all of the pages mapped by the process's address space to be memory resident until unlocked by a call to the
       munlockall function, until the process exits, or until the process calls exec.  MCL_CURRENT locks all of the pages  currently  mapped  into
       the  process's  address	space.	MCL_FUTURE  locks all of the pages that become mapped into the process's address space in the future, when
       those mappings are established. You can specify MCL_CURRENT and subsequently specify MCL_FUTURE to lock both  current  and  future  address
       space.

       The  munlockall	function unlocks all currently mapped pages of the process's address space.  Any pages that become mapped into a process's
       address space after a call to munlockall are not locked unless otherwise specified by a subsequent call to mlockall. Pages locked or mapped
       into another process's address space are unaffected by this process's call to the munlockall function.

       Locking the process's pages into memory also makes the process unswappable.  When the pages are unlocked, the process is made swappable.

       A  lock is not inherited across a fork.	All memory locks established on an address by this process are removed if an address range associ-
       ated with the lock is unmapped with a call to the munmap function.

       You must have superuser privileges to call the mlockall function.

RETURN VALUES

       On a successful call to the mlockall function, a value of 0 (zero) is returned and memory is locked.  On an unsuccessful call, a  value	of
       -1 is returned, no memory is locked, and errno is set to indicate that an error occurred.

       On  a  successful call to the munlockall function, a value of 0 (zero) is returned and memory is unlocked. On an unsuccessful call, a value
       of -1 is returned and errno is set to indicate that an error occurred.

ERRORS

       The mlockall and munlockall functions fail under the following condition:

       [ENOSYS]       The implementation does not support this memory locking interface.

       If any of the following conditions occur, the mlockall function fails:

       [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.

       [ENOMEM]       Locking all of the pages currently mapped into the process's address space exceeds 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.

RELATED INFORMATION

       Functions: exec(2), _exit(2), fork(2), munmap(2)

       Guide to Realtime Programming delim off

																       mlockall(3)