---

3.2.3.9 Statistics for Memory Allocation with malloc ¶

You can get information about dynamic memory allocation by calling the mallinfo2 function. This function and its associated data type are declared in malloc.h; they are an extension of the standard SVID/XPG version.

Data Type: struct mallinfo2 ¶

This structure type is used to return information about the dynamic memory allocator. It contains the following members:

size_t arena

This is the total size of memory allocated with sbrk by malloc, in bytes.

size_t ordblks

This is the number of chunks not in use. (The memory allocator internally gets chunks of memory from the operating system, and then carves them up to satisfy individual malloc requests; see The GNU Allocator.)

size_t smblks

This field is unused.

size_t hblks

This is the total number of chunks allocated with mmap.

size_t hblkhd

This is the total size of memory allocated with mmap, in bytes.

size_t usmblks

This field is unused and always 0.

size_t fsmblks

This field is unused.

size_t uordblks

This is the total size of memory occupied by chunks handed out by malloc.

size_t fordblks

This is the total size of memory occupied by free (not in use) chunks.

size_t keepcost

This is the size of the top-most releasable chunk that normally borders the end of the heap (i.e., the high end of the virtual address space’s data segment).

Function: struct mallinfo2 mallinfo2 (void) ¶

Preliminary: | MT-Unsafe init const:mallopt | AS-Unsafe init lock | AC-Unsafe init lock | See POSIX Safety Concepts.

This function returns information about the current dynamic memory usage in a structure of type struct mallinfo2.