malloc_trim

<html> <head> <title>malloc_trim</title> <META NAME="KEYWORDS" CONTENT="malloc_trim"> </head> <body BGCOLOR="#ffffff" LINK="#0000ff" VLINK="#0000ff" ALINK="#0000ff" TEXT="#000000"> <center> <h1>malloc_trim</h1></center> <PRE> <A HREF="/man3/MALLOC_TRIM">MALLOC_TRIM(3)</A> Linux Programmer's Manual <A HREF="/man3/MALLOC_TRIM">MALLOC_TRIM(3)</A> 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 <A HREF="/man2/sbrk">sbrk(2)</A> or <A HREF="/man2/madvise">madvise(2)</A> 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 <A HREF="/man2/sbrk">sbrk(2)</A>. 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 at- <A HREF="/man7/tributes">tributes(7)</A>. +--------------+---------------+---------+ |Interface | Attribute | Value | +--------------+---------------+---------+ |malloc_trim() | Thread safety | MT-Safe | +--------------+---------------+---------+ CONFORMING TO This function is a GNU extension. NOTES This function is automatically called by <A HREF="/man3/free">free(3)</A> in certain circum- stances; see the discussion of M_TOP_PAD and M_TRIM_THRESHOLD in mal- <A HREF="/man3/lopt">lopt(3)</A>. Only the main heap (using <A HREF="/man2/sbrk">sbrk(2)</A>) 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 <A HREF="/man2/sbrk">sbrk(2)</A>, <A HREF="/man3/malloc">malloc(3)</A>, <A HREF="/man3/mallopt">mallopt(3)</A> COLOPHON This page is part of release 5.05 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 https://www.kernel.org/doc/man-pages/. Linux 2019-05-09 <A HREF="/man3/MALLOC_TRIM">MALLOC_TRIM(3)</A></PRE> <center> <h6>Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2025 <a href="http://www.he.net">Hurricane Electric</a>. All Rights Reserved.</h6></center> </body> </html>

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malloc_trim