Effect of replacing RMW with W in optimistic lock write unlock

baseline, patch

Statistically significant speedups >= 1% (negative means slowdowns)

Key prefix

• unpredictable_leaf_key_prefix_split<unodb::olc_db>: 1%
• unpredictable_cut_key_prefix<unodb::olc_db>: 3%

N4

• full_n4_sequential_insert<unodb::olc_db>/100: 1%
• full_n4_random_insert<unodb::olc_db>/65535: 1%
• minimal_n4_sequential_insert<unodb::olc_db>/16: 2%
• minimal_n4_sequential_insert<unodb::olc_db>/64: 1%
• minimal_n4_sequential_insert<unodb::olc_db>/255: 1%
• minimal_n4_random_insert<unodb::olc_db>/16: 1%
• minimal_n4_random_insert<unodb::olc_db>/64: 1%
• minimal_n4_random_insert<unodb::olc_db>/255: 1%
• full_n4_sequential_delete<unodb::olc_db>/4096: -1%
• full_n4_random_deletes<unodb::olc_db>/65534: 1%
• full_n4_to_minimal_random_delete<unodb::olc_db>/100: -1%
• full_n4_to_minimal_random_delete<unodb::olc_db>/512: -1%
• full_n4_to_minimal_random_delete<unodb::olc_db>/4096: -1%
• shrink_node16_to_n4_randomly<unodb::olc_db>/512: 1%