The Cost of Memory Fragmentation

This episode explores memory fragmentation in computer systems, differentiating between external and internal fragmentation. The host begins by contrasting different types of fragmentation, focusing on memory fragmentation and its impact on operating system performance. Against this backdrop, the discussion delves into memory allocation strategies, highlighting the inefficiencies of allocating exactly the requested memory and the resulting external fragmentation. More significantly, the host explains how fixed-block size allocation addresses external fragmentation but introduces internal fragmentation, where allocated blocks contain unused space. Virtual memory, with its paging mechanism, is presented as a solution, although it introduces the cost of translating virtual addresses to physical addresses, potentially leading to performance degradation due to increased RAM access time. The host concludes by discussing how Memcached mitigates internal fragmentation and speculates on the potential impact of memory fragmentation on the performance differences observed between MySQL 8 and MySQL 5, suggesting that a large codebase can exacerbate the problem. This analysis offers valuable insights into the complexities of memory management and its subtle but potentially significant impact on software performance.