one question about LRU mechanism

["liyu@WAN" <liyu@ccoss.com.cn>]

Hello everybody:

	I am a linux kernel newbie. 

	I am reading memory managment code of kernel 2.6.11.11.
I found LRU is implement as linked-stack in linux, include two important
data structure linked-list :
zone->active_list and zone->inactive_list. when kernel need reclaim some
pages, it will call function refiil_inactive_list() ultimately to move
some page from active_list to inactive_list.

	It's OK, but I have one question in my mind:
I found all function that append page to active_list, it just append
page to head of active_list (use inline function list_add() ), but
refill_inactive_list() also start scanning from head of active_list, I
think the better way scan active_list is start from rear of active_list
and scan though prev member of list_head at reclaim pages. Scanning
start from head of active_list may make thrashing more possibly, I
think. and, in my view, "head of active_list" is zone->active_list,
"rear of active_list" is zone->active_list.prev .

	May be, I am failed understand mm? or what's wrong?

	Thanks in advanced.

	Alas, my english so bad.

						liyu