debian man page for malloc_trim

MALLOC_TRIM(3)						     Linux Programmer's Manual						    MALLOC_TRIM(3)

NAME
       malloc_trim - release free memory from the top of the heap

SYNOPSIS
       #include <malloc.h>

       void malloc_trim(size_t pad);

DESCRIPTION
       The malloc_trim() function attempts to release free memory at the top of the heap (by calling sbrk(2) with a suitable argument).

       The  pad  argument  specifies  the amount of free space to leave untrimmed at the top of the heap.  If this argument is 0, only the minimum
       amount of memory is maintained at the top of the heap (i.e., one page or less).	A nonzero argument can be used to maintain  some  trailing
       space at the top of the heap in order to allow future allocations to be made without having to extend the heap with sbrk(2).

RETURN VALUE
       The malloc_trim() function returns 1 if memory was actually released back to the system, or 0 if it was not possible to release any memory.

ERRORS
       No errors are defined.

CONFORMING TO
       This function is a GNU extension.

NOTES
       This  function  is  automatically  called by free(3) in certain circumstances; see the discussion of M_TOP_PAD and M_TRIM_THRESHOLD in mal-
       lopt(3).

       This function cannot release free memory located at places other than the top of the heap.

NOTES
       This function only releases memory in the main arena.

SEE ALSO
       sbrk(2), malloc(3), mallopt(3)

COLOPHON
       This page is part of release 3.44 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2012-03-29							    MALLOC_TRIM(3)