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.

CONFORMING TO
       This function is a GNU extension.

NOTES
       This function is automatically called by free(3) in certain circumstances; see the discus‐
       sion of M_TOP_PAD and M_TRIM_THRESHOLD in mallopt(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 3.74 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 http://www.kernel.org/doc/man-pages/.



Linux                                       2014-05-28                             MALLOC_TRIM(3)