Thanks, understood. However file-backed pages such as executables and shared libs are not written to swap space as the pages are just dropped and read back in from the regular(non-swap) filesystem no? Not that causes any less disk I/O of course but they are not anonymous pages which is generally what is written to swap. When I think swap I think of "written to swap" but maybe you mean swap in the general sense of paged out?

Yes, I meant "swapped out" in the general sense of "paged out". On the other hand, if you have actual swap space, hot code pages will be much less likely to be paged out than colder anonymous pages.