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A constant-time dynamic storage allocator for real-time systems


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 behaviour 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.

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Author information

Correspondence to Alfons Crespo.

Additional information

This work was partially supported by FRESCOR (IST/5-034026), ARTIST2 (IST NoE 004527) and Thread (TIC2005-08665).

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Masmano, M., Ripoll, I., Balbastre, P. et al. A constant-time dynamic storage allocator for real-time systems. Real-Time Syst 40, 149–179 (2008). https://doi.org/10.1007/s11241-008-9052-7

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  • Dynamic storage allocation
  • Real-time allocators
  • Allocation algorithms evaluation