Understanding DRAM Internals: How Channels, Banks, and DRAM Access Patterns Impact Performance

Software performance hinges on efficient memory access, exceeding the importance of raw CPU speed. DRAM architecture significantly impacts access speed, with sequential access proving faster than random access. Two key factors determine memory performance: access time per fetch and the number of accesses. This analysis focuses on DRAM access latency and its internal workings. DRAM comprises channels, ranks, banks, rows, columns, and a row buffer; each element plays a crucial role in data retrieval. Access time varies depending on row buffer hits, misses, or conflicts, resulting in latency differences. A shared data bus creates a bottleneck, especially during bursty random access, where contention delays are amplified. Bank access serialization further contributes to slower random access due to row switching delays. Sequential access benefits from caching and prefetching, minimizing DRAM accesses and latency. Conversely, random access suffers from increased latency due to unpredictable access patterns and the inability to leverage hardware optimizations effectively. Ultimately, while random access can be slower, efficient data structures can mitigate its impact on overall performance.