How cache memory works?

Question

Today when I was in computer organization class, teacher talked about something interesting to me. When it comes to talk about Why cache memory works, he said that:

Answer 1

There is a very good paper by Ulrich Drepper of Red Hat and glibc fame, What Every Programmer Should Know About Memory. One section discussed caches in great detail. For example, there are cache effects in SMP systems where CPUs can end up thrashing ownership of a modified cache line back and forth, greatly harming performance.