if overcommit is disabled, then the system drops its internal caches (dentry cache, pagecache) to satisfy a memory allocation. Since most applications don't touch pages they allocate, that means the OS could have avoided dropping the caches. Since it did drop the caches, other parts of the system will then have to do more work to reconstruct the caches (looking up an dentry explicitly, or loading a page from disk instead of RAM).
Everything I'm describing is about a busy server with heterogenous workloads of specific types.
Everything I'm describing is about a busy server with heterogenous workloads of specific types.