Some kernel settings have different names with different versions. For instance, sched_migration_cost_ns is renamed sched_migration_cost in the older kernel releases. In the most recent kernels, the setting is missing entirely. In addition, dirty_background_ratio and dirty_ratio have been replaced for a very good reason.
Imagine a server with 512 GB of RAM. In such a case, up to 5 GB of memory could be dirty before the operating system writes anything to disk. In the event of an emergency flush, the disk subsystem may not be capable of handling such a large amount. The new settings allow us to use the same logic as before, but with bytes instead of percentages. In systems with more than 64 GB of RAM, we highly recommend upgrading ...
