Johnny Cache - The End of DRAM Cache Conflicts in Tiered Main Memory Systems

Explore a groundbreaking approach to hardware management in tiered memory systems through this conference talk from OSDI '23. Delve into the innovative "Johnny Cache" system that effectively eliminates DRAM cache conflicts, outperforming current software management methods. Learn how low-overhead conflict avoidance techniques, implemented at cache line granularity, can significantly boost performance for various applications. Discover the two key techniques explored: conflict avoidance during page allocation and dynamic remapping based on memory access sampling. Examine the implementation of these techniques in the Linux kernel on an Intel Optane machine and compare the performance of Johnny Cache against default Linux tiered memory management and the state-of-the-art HeMem system. Gain insights into the surprising conclusion that minimizing conflicts at page allocation time can achieve near-optimal cache performance without extensive monitoring or dynamic page remapping.