Anonymous user
Memory Allocation: Difference between revisions
mentioned fixed size memory allocation →A very very simple Memory Manager
| [unchecked revision] | [unchecked revision] |
(information on porting an existing memory allocator) |
(mentioned fixed size memory allocation →A very very simple Memory Manager) |
||
Line 33:
What data structure and algorithms can be used with such lists has been discussed in [http://www.mega-tokyo.com/forum/index.php?board=1;action=display;threadid=6486 Memmaker's] started thread (as well as in many others)
-->
==Fixed size allocation==
Allocating and deallocating fixed sized areas of memory is extremely simple. You can basically treat all free memory as a linked list of nodes. To allocate memory, you remove the front node from the linked list. To free memory, you return the front node to the linked list. This provides a constant allocation/releasing time and there is no fragmentation.
In the real world, programs like to allocate different sized chunks of memory so it's unlikely you can solely rely on this method.
However, it is theoretically possible for a microkernel to be designed so that all memory structures are exactly the same size (the Process struct, Thread struct, Message struct, etc). This would be very fast and efficient.
On this note, most Lisp implementations have a single 'box-and-pointer' base data type. A box-and-pointer type is a pair of values, usually pointer/pointer or atom/pointer (atom means a numeric value). On a 32-bit system, this structure is 8 bytes big. All other data structures (lists, trees, objects, etc) are built on top of this type. As a consequence memory allocation on a Lisp system is very fast.
==Tips to go further==
| |||