MALLOC_TRIM(3) - man page online | library functions

Release free memory from the top of the heap.

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 circumstances; see the discus‐ sion 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 This page is part of release 4.04 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 2015-07-23 MALLOC_TRIM(3)
This manual Reference Other manuals
malloc_trim(3) referred by mallinfo(3) | malloc(3) | mallopt(3)
refer to attributes(7) | brk(2) | malloc(3) | mallopt(3)