malloc_trim(3) — Linux manual page


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

NAME         top

       malloc_trim - release free memory from the heap

SYNOPSIS         top

       #include <malloc.h>

       int malloc_trim(size_t pad);

DESCRIPTION         top

       The malloc_trim() function attempts to release free memory from
       the heap (by calling sbrk(2) or madvise(2) with suitable

       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         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 memory.

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

       Only the main heap (using sbrk(2)) honors the pad argument;
       thread heaps do not.

       Since glibc 2.8 this function frees memory in all arenas and in
       all chunks with whole free pages.

       Before glibc 2.8 this function only freed memory at the top of
       the heap in the main arena.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.13 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

Linux                          2021-03-22                 MALLOC_TRIM(3)

Pages that refer to this page: mallinfo(3)malloc(3)mallopt(3)