projects / thirdparty / man-pages.git / blame
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1 | .\" Copyright (c) 2012 by Michael Kerrisk <mtk.manpages@gmail.com> |
| 2 | .\" | |
| 5fbde956 | 3 | .\" SPDX-License-Identifier: Linux-man-pages-copyleft |
| a15b0e60 | 4 | .\" |
| ab47278f | 5 | .TH MALLOC_TRIM 3 (date) "Linux man-pages (unreleased)" |
| a15b0e60 | 6 | .SH NAME |
| 0deebbe5 | 7 | malloc_trim \- release free memory from the heap |
| 0f03517a AC |
8 | .SH LIBRARY |
| 9 | Standard C library | |
| 8fc3b2cf | 10 | .RI ( libc ", " \-lc ) |
| a15b0e60 | 11 | .SH SYNOPSIS |
| c7db92b9 | 12 | .nf |
| a15b0e60 | 13 | .B #include <malloc.h> |
| dbfe9c70 | 14 | .PP |
| 7b7fbe78 | 15 | .BI "int malloc_trim(size_t " pad ); |
| c7db92b9 | 16 | .fi |
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17 | .SH DESCRIPTION |
| 18 | The | |
| 19 | .BR malloc_trim () | |
| 0deebbe5 | 20 | function attempts to release free memory from the heap |
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21 | (by calling |
| 22 | .BR sbrk (2) | |
| 0deebbe5 CD |
23 | or |
| 24 | .BR madvise (2) | |
| 25 | with suitable arguments). | |
| 847e0d88 | 26 | .PP |
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27 | The |
| 28 | .I pad | |
| 29 | argument specifies the amount of free space to leave untrimmed | |
| 30 | at the top of the heap. | |
| 31 | If this argument is 0, only the minimum amount of memory is maintained | |
| 32 | at the top of the heap (i.e., one page or less). | |
| 33 | A nonzero argument can be used to maintain some trailing space | |
| 34 | at the top of the heap in order to allow future allocations | |
| 35 | to be made without having to extend the heap with | |
| 36 | .BR sbrk (2). | |
| 37 | .SH RETURN VALUE | |
| 38 | The | |
| 39 | .BR malloc_trim () | |
| 40 | function returns 1 if memory was actually released back to the system, | |
| 41 | or 0 if it was not possible to release any memory. | |
| 42 | .SH ERRORS | |
| 43 | No errors are defined. | |
| 44 | .\" .SH VERSIONS | |
| 45 | .\" Available already in glibc 2.0, possibly earlier | |
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46 | .SH ATTRIBUTES |
| 47 | For an explanation of the terms used in this section, see | |
| 48 | .BR attributes (7). | |
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49 | .ad l |
| 50 | .nh | |
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51 | .TS |
| 52 | allbox; | |
| c466875e | 53 | lbx lb lb |
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54 | l l l. |
| 55 | Interface Attribute Value | |
| 56 | T{ | |
| 57 | .BR malloc_trim () | |
| 58 | T} Thread safety MT-Safe | |
| 59 | .TE | |
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60 | .hy |
| 61 | .ad | |
| 847e0d88 | 62 | .sp 1 |
| 3113c7f3 | 63 | .SH STANDARDS |
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64 | This function is a GNU extension. |
| 65 | .SH NOTES | |
| 0deebbe5 | 66 | Only the main heap (using |
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67 | .BR sbrk (2)) |
| 68 | honors the | |
| 69 | .I pad | |
| 70 | argument; thread heaps do not. | |
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71 | .PP |
| 72 | Since glibc 2.8 this function frees memory in all arenas and in all | |
| 73 | chunks with whole free pages. | |
| 74 | .\" See commit 68631c8eb92ff38d9da1ae34f6aa048539b199cc | |
| 75 | .\" (dated 2007-12-16) which adds iteration over all | |
| 76 | .\" arenas and frees all pages in chunks which are free. | |
| 847e0d88 | 77 | .PP |
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78 | Before glibc 2.8 this function only freed memory at the |
| 79 | top of the heap in the main arena. | |
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80 | .SH SEE ALSO |
| 81 | .BR sbrk (2), | |
| 82 | .BR malloc (3), | |
| 83 | .BR mallopt (3) |