malloc_trim(3)             Library Functions Manual             malloc_trim(3)

NAME
       malloc_trim - release free memory from the heap

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <malloc.h>

       int malloc_trim(size_t pad);

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

       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 |
       +--------------------------------------------+---------------+---------+
STANDARDS
       GNU.

VERSIONS
       glibc 2.0.

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

Linux man-pages 6.7               2023-10-31                    malloc_trim(3)