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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  circum-
     stances;  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.