Page Reclamation V (Periodic Reclaim) - kswapd and vmscan.c

this is a kernel thread, runs one instance globally. because we need atomic memory allocation. so we should maintain a fairly descent amount of free pages in the system. try_to_free_pages does its work when mem is scarce which is a time consuming (not atomic) job to do.

each memory node has a kswapd which sleeps on kswapd_wait queue of that node.

reclaiming is done on behalf of a process.