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>

       int 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.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +--------------+---------------+---------+
       |Interface     | Attribute     | Value   |
       +--------------+---------------+---------+
       |malloc_trim() | Thread safety | MT-Safe |
       +--------------+---------------+---------+

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.

       This function releases only memory in the main arena.

SEE ALSO

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

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Linux                                                               2017-09-15                                                      MALLOC_TRIM(3)