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相变内存(PCM)是一种使用相变材料存储数据的内存技术,具有非易失、存储密度高、低能耗和扩展性强等优点,但也存在写操作次数有限的缺陷。为了克服该问题,近期的研究主要集中在优化写操作和磨损均衡技术2个方面,但这些技术对于快速磨损PCM并使之失效的恶意攻击还存在一定的缺陷。该文提出一种PCM磨损均衡方法,将内存分成2个层级,不同的层级拥有各自独立的地址随机映射表,不同层级的内存单元根据该表将逻辑地址转换为物理地址。同时,地址随机映射表根据不同层级的写操作次数阈值进行动态更新。该方法不仅实现了PCM的磨损均衡,而且能够抵御恶意磨损程序的攻击。实验表明:相比已有的3种磨损均衡方法,该方法的磨损均衡效果提升高达87.5%;同时,对性能的影响不超过6%,增加的存储开销不超过内存总体大小的1‰。
Phase-change memory (PCM) is a memory technology that uses phase-change materials to store data. It has the advantages of non-volatility, high memory density, low power consumption and scalability, but also has a limited number of write operations. In order to overcome this problem, recent studies have focused on optimizing write operations and wear leveling techniques. However, these techniques have some drawbacks to malicious attacks that rapidly wear out PCMs and invalidate them. In this paper, we propose a PCM wear leveling method, which divides the memory into two levels. Different levels have their own independent address random mapping tables. Different levels of memory cells convert the logical addresses into physical addresses according to the table. At the same time, the address random mapping table dynamically updated according to the threshold of the number of write operations at different levels. This method not only achieves PCM wear leveling, but also attacks the malicious wear program. Experiments show that compared with the existing three wear leveling methods, the wear leveling effect of this method is improved up to 87.5%. Meanwhile, the impact on performance is no more than 6%, and the additional storage overhead does not exceed 1% of the total memory size.