3 ms·

The description of the current system as being composed of two LRU queues sound a lot like the 2Queues cache replacement algorithm. However, I was under the imp

• NovaX 6y ago
  They decided against it, I believe because ClockPro was too complicated (but maybe NIH?). Instead they devised their own algorithm, DClock, borrowing ideas but is also different [1]. They use an ad hoc sizing rule (50%-99%) [2] which can dramatically impact its performance, neither extreme being universally better. When reimplementing their algorithm for analysis, the hit rates skewed towards being okay but not great [3]. You can compare ClockPro [4] and DClock [5] in the simulator. [1] https://github.com/torvalds/linux/blob/ac3a0c8472969a03c0496ae774b3a29eb26c8d5a/mm/workingset.c https://github.com/torvalds/linux/blob/ac3a0c8472969a03c0496... [2] https://github.com/torvalds/linux/blob/1590a2e1c681b0991bd42c992cabfd380e0338f2/mm/vmscan.c#L2176-L2204 https://github.com/torvalds/linux/blob/1590a2e1c681b0991bd42... [3] https://docs.google.com/spreadsheets/d/16wEq5QBzqOtownEtZvZeFn9i_iV0TPE8je4ADwlMNM8/edit#gid=1925412315 https://docs.google.com/spreadsheets/d/16wEq5QBzqOtownEtZvZe... [4] https://github.com/ben-manes/caffeine/blob/master/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/irr/ClockProPolicy.java https://github.com/ben-manes/caffeine/blob/master/simulator/... [5] https://github.com/ben-manes/caffeine/blob/master/simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/irr/DClockPolicy.java https://github.com/ben-manes/caffeine/blob/master/simulator/...