ovsdb-server uses a lot of hash maps, but it never actually calls hmap_shrink(). For example, if we will create a lot of logical switches and ports for some special case and than remove all of them, ovsdb-server will not return consumed memory to the system. We need to explore how much memory we could save in such case and actually shrink hash maps if needed. 'table->rows' might be a good candidate. For the reference, concurrent hash maps in OVS (cmap) shrinks automatically if memory usage is below than 20% of allocated space. We might consider similar approach.