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Real-Time applications can require dynamic storage management. However this feature has been sistematically avoided due to the general belief about the poor performance of allocation and deallocation operations in time and space. Actually, the use of Java technologies in real-time require to analyse in detail the performance of this feature due to its intensive use. In a previous paper, the authors proposed a new dynamic storage allocator that perform malloc and free operations in constant time (O(1)) with a very high efficiency. In this paper, we compare the behaviour of several allocators under "real-time" loads measuring the temporal cost and the fragmentation incurred by each allocator. In order to compare the temporal cost of the allocators, two parameters have been considered: number of instructions and processor cycles. To measure the fragmentation, we have calculated the relation between the maximum memory used by the each allocator relative to the point of the maximum amount of memory used by the load. Additionally, we have measured the impact of delayed deallocation in a similar way a periodic garbage collector server will do. The results of this paper show that TLSF allocator obtains the best resuts when both aspects, temporal and spatial are considered.

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Abstract. Dynamic memory allocation has been used for decades. However, it has seldom been used in real-time systems since the worst case of spatial and temporal requirements for allocation and deallocation operations is either unbounded or bounded but with a very large bound.In this paper, a new allocator called TLSF (Two Level Segregated Fit) is presented. TLSF is designed and implemented to accommodate real-time constraints. The proposed allocator exhibits time-bounded behaviour, O(1), and maintains a very good execution time. This paper describes in detail the data structures and functions provided by TLSF. We also compare TLSF with a representative set of allocators regarding their temporal cost and fragmentation.Although the paper is mainly focused on timing analysis, a brief study and comparative analysis of fragmentation incurred by the allocators has been also included in order to provide a global view of the behavior of the allocators.The temporal and spatial results showed that TLSF is also a fast allocator and produces a fragmentation close to that caused by the best existing allocators.