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

NAME         top

       malloc_trim - release free memory from the top of the heap

SYNOPSIS         top

       #include <malloc.h>

       int malloc_trim(size_t pad);

DESCRIPTION         top

       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

RETURN VALUE         top

       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

ERRORS         top

       No errors are defined.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface     Attribute     Value   │
       │malloc_trim() │ Thread safety │ MT-Safe │

CONFORMING TO         top

       This function is a GNU extension.

NOTES         top

       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         top

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

COLOPHON         top

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       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

Linux                            2015-07-23                   MALLOC_TRIM(3)