I stopped the tests and waited 90 minutes. The number of entries did not go down at all. Few minutes before stopping the tests: (gdb) print lru_state $1 = {entries_hiwat = 500000, entries_used = 954943, chunks_hiwat = 100000, chunks_used = 1742, fds_system_imposed = 400000, fds_hard_limit = 396000, fds_hiwat = 360000, fds_lowat = 200000, futility = 0, per_lane_work = 50, biggest_window = 160000, prev_fd_count = 0, prev_time = 1548862024, fd_state = 0} 30 minutes after stopping the tests: (gdb) print lru_state $1 = {entries_hiwat = 500000, entries_used = 954944, chunks_hiwat = 100000, chunks_used = 1742, fds_system_imposed = 400000, fds_hard_limit = 396000, fds_hiwat = 360000, fds_lowat = 200000, futility = 0, per_lane_work = 50, biggest_window = 160000, prev_fd_count = 0, prev_time = 1548863824, fd_state = 0} 90 minutes after stopping the tests: (gdb) print lru_state $1 = {entries_hiwat = 500000, entries_used = 954944, chunks_hiwat = 100000, chunks_used = 1742, fds_system_imposed = 400000, fds_hard_limit = 396000, fds_hiwat = 360000, fds_lowat = 200000, futility = 0, per_lane_work = 50, biggest_window = 160000, prev_fd_count = 0, prev_time = 1548867350, fd_state = 0}