innodb cache duplication due to os page cache and buffer pool We have set our innodb buffer pool 80% of total memory. Mysql page allocation gets stalled sometimes when page cache is occupying memory. Now since mysql is caching table rows and indexes and follows a lifecycle to flush them, doesn't OS page cache have the same data in terms of files? Doesn't it cause cache duplicity and increase in memory usage? If data is duplicated can we assume flushing OS page cache we would have no impact on performance of mysql as innodb buffer pool has hot/active data?
Hence the recommendation of using O_DIRECT.