jammy (3) malloc_trim.3.gz

NAME

       malloc_trim - release free memory from the heap

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 │
       └──────────────┴───────────────┴─────────┘

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).

       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)

COLOPHON

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