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| .TH MALLOC_TRIM 3 2017-09-15 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| malloc_trim \- release free memory from the top of the heap |
| .SH SYNOPSIS |
| .B #include <malloc.h> |
| .PP |
| .BI "int malloc_trim(size_t " pad ); |
| .SH DESCRIPTION |
| The |
| .BR malloc_trim () |
| function attempts to release free memory at the top of the heap |
| (by calling |
| .BR sbrk (2) |
| with a suitable argument). |
| .PP |
| The |
| .I 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 |
| .BR sbrk (2). |
| .SH RETURN VALUE |
| The |
| .BR 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. |
| .SH ERRORS |
| No errors are defined. |
| .\" .SH VERSIONS |
| .\" Available already in glibc 2.0, possibly earlier |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .TS |
| allbox; |
| lb lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR malloc_trim () |
| T} Thread safety MT-Safe |
| .TE |
| .sp 1 |
| .SH CONFORMING TO |
| This function is a GNU extension. |
| .SH NOTES |
| This function is automatically called by |
| .BR free (3) |
| in certain circumstances; see the discussion of |
| .B M_TOP_PAD |
| and |
| .B M_TRIM_THRESHOLD |
| in |
| .BR mallopt (3). |
| .PP |
| This function cannot release free memory located at places |
| other than the top of the heap. |
| .PP |
| This function releases only memory in the main arena. |
| .\" malloc/malloc.c::mTRIm(): |
| .\" return result | (av == &main_arena ? sYSTRIm (pad, av) : 0); |
| .SH SEE ALSO |
| .BR sbrk (2), |
| .BR malloc (3), |
| .BR mallopt (3) |