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 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

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       information   about   reporting   bugs,   and   the  latest  version  of  this  page,  can  be  found  at
       http://www.kernel.org/doc/man-pages/.

Linux                                              2015-07-23                                     MALLOC_TRIM(3)