what are the effects of paging on garbage collection ?
The effects of paging on garbage-collection are pretty much the same as upon anything; it allows access to lots of memory, but hurts performance when it happens.
The more pressing question, is what is the effect of garbage-collection on paging?
Garbage collection can cause areas of memory to be read from and written to that would not be considered otherwise at a given point of time. Reducing the degree to which garbage collection causes paging to happen is therefore advantageous. This is one of the advantages that a generational compacting collector offers, as it leads to more short-lived objects being in one page, collected from that page, and the memory made available to other objects, while also keeping long-lived objects in a page where related objects are more likely to also be (long-lived objects will often be related to other long-lived objects because one long-lived object is keeping the others alive). This not only reduces the amount of paging necessary to perform the collection, but can help reduce the amount of paging necessary for the rest of the application.