Design And Realization Of A Dynamic Memory Manager For Embedded Real-time Systems

With the development of Internet of Things technology, embedded real-timeoperating systems are more widely used. Embedded real-time operating system forreal-time dynamic memory allocation, fragmentation, reliability have higherrequirements, therefore, the dynamic memory allocation has become embeddedreal-time operating system is an important research content. Existing memorymanagement by sacrificing memory utilization to meet real-time requirements, resultingin a waste of memory resources. In addition, embedded system processor generally donot have a memory management unit, memory management, real-time operating systemcan not protect the memory, could easily lead to cross-border access memory, reduce thereliability of the system. To this end, improve memory utilization and memory securityfeatures for dynamic memory allocation performance is important.To address the problem on the basis of embedded real-time system memorymanagement algorithms TLSF (Two-level Segregated Fit) for less than its memoryallocation and release, as well as defects in the memory protection, research withoutreducing the system real-time under the premise of reducing memory fragmentation rate,by adding two bitmap algorithm proposed new data structure, to add memorycross-border access to protection mechanisms, completed a new embedded real-timesystems dynamic memory management ERMM (Embedded Real-time MemoryManager) design. The main work includes:1) analysis of the dynamic memory management algorithm commonly used inembedded real-time operating system, real-time and memory fragmentation rate ofdifferent dynamic memory allocation algorithm (DSA) are discussed, based on theembedded real-time systems for real-time and memory fragmentation rate requirements,the proposed algorithm TLSF-based embedded real-time systems dynamic memorymanagement, memory management program.2) conduct a detailed analysis the TLSF algorithm, proposed a new embeddedreal-time systems dynamic memory allocation manager (Ermm). For TLSF algorithmshortcomings of low efficiency in small memory allocation proposed new data structure,the different sizes of memory requests to take a different allocation strategies. Smallmemory requests, to accelerate the search speed take two bitmaps algorithm to reducethe allocation of time and space for time strategy to reduce external memory fragmentation; large memory request, improved TLSF algorithm: take the lower limit ofits memory allocation " cutting strategy proposed precision-cut improvement strategiesto reduce the rate of internal memory fragmentation; release its memory free memoryblock Now Merge strategy proposed delay Merge improvement strategies to improvereal-time; reliability, to take the memory cross-border conservation measures toimprove the security of memory management.3) TLSF algorithm and ERMM of OS-III system implementation in the memoryfragmentation rate and real-time experimental comparison of these two approaches, andthe memory security ERMM test. Experimental results show that the the Ermm dynamicmemory allocation manager has better real-time, high reliability, and low memoryfragmentation, which can effectively improve the performance of the memorymanagement of embedded real-time systems.