Internally, Oracle uses various types of structures to control access to elements of the databases including latches and various types of enqueueing (locking) mechanisms. Latches are an elemental locking mechanism that are the primary means used to control access to Oracle internal structures, such as internal memory structures in the SGA. The database buffer cache is a memory area in the Shared Global Area (SGA) where Oracle keeps copies of database blocks. Latching issues can be one major source of performance problems within an Oracle database.
This is a companion discussion topic for the original entry at https://blog.toadworld.com/categoryreducing_contention_for_the_cache_buffer_chains_latch