Content-type: text/html Man page of mlockall

mlockall

Section: C Library Functions (3)
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NAME

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

SYNOPSIS

#include <sys/mman.h>

int mlockall (
int flags);

int munlockall (void);  

PARAMETERS

flags
The flags argument 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 then 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 associated 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 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 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 conditions:

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

If any of the following conditions occur, the mlockall function will fail:

[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 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.
 

RELATED INFORMATION

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


 

Index

NAME
SYNOPSIS
PARAMETERS
DESCRIPTION
RETURN VALUES
ERRORS
RELATED INFORMATION

This document was created by man2html, using the manual pages.
Time: 02:41:58 GMT, October 02, 2010