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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2009-01-07 18:08:01 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-08 08:31:05 -0800
commit08e552c69c6930d64722de3ec18c51844d06ee28 (patch)
treea744d57ed4b23401115f1033dcaac9e85d550e09 /mm/vmscan.c
parent8c7c6e34a1256a5082d38c8e9bd1474476912715 (diff)
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memcg: synchronized LRU
A big patch for changing memcg's LRU semantics. Now, - page_cgroup is linked to mem_cgroup's its own LRU (per zone). - LRU of page_cgroup is not synchronous with global LRU. - page and page_cgroup is one-to-one and statically allocated. - To find page_cgroup is on what LRU, you have to check pc->mem_cgroup as - lru = page_cgroup_zoneinfo(pc, nid_of_pc, zid_of_pc); - SwapCache is handled. And, when we handle LRU list of page_cgroup, we do following. pc = lookup_page_cgroup(page); lock_page_cgroup(pc); .....................(1) mz = page_cgroup_zoneinfo(pc); spin_lock(&mz->lru_lock); .....add to LRU spin_unlock(&mz->lru_lock); unlock_page_cgroup(pc); But (1) is spin_lock and we have to be afraid of dead-lock with zone->lru_lock. So, trylock() is used at (1), now. Without (1), we can't trust "mz" is correct. This is a trial to remove this dirty nesting of locks. This patch changes mz->lru_lock to be zone->lru_lock. Then, above sequence will be written as spin_lock(&zone->lru_lock); # in vmscan.c or swap.c via global LRU mem_cgroup_add/remove/etc_lru() { pc = lookup_page_cgroup(page); mz = page_cgroup_zoneinfo(pc); if (PageCgroupUsed(pc)) { ....add to LRU } spin_lock(&zone->lru_lock); # in vmscan.c or swap.c via global LRU This is much simpler. (*) We're safe even if we don't take lock_page_cgroup(pc). Because.. 1. When pc->mem_cgroup can be modified. - at charge. - at account_move(). 2. at charge the PCG_USED bit is not set before pc->mem_cgroup is fixed. 3. at account_move() the page is isolated and not on LRU. Pros. - easy for maintenance. - memcg can make use of laziness of pagevec. - we don't have to duplicated LRU/Active/Unevictable bit in page_cgroup. - LRU status of memcg will be synchronized with global LRU's one. - # of locks are reduced. - account_move() is simplified very much. Cons. - may increase cost of LRU rotation. (no impact if memcg is not configured.) Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f63b20dd771..45983af1de3 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -512,7 +512,6 @@ redo:
lru = LRU_UNEVICTABLE;
add_page_to_unevictable_list(page);
}
- mem_cgroup_move_lists(page, lru);
/*
* page's status can change while we move it among lru. If an evictable
@@ -547,7 +546,6 @@ void putback_lru_page(struct page *page)
lru = !!TestClearPageActive(page) + page_is_file_cache(page);
lru_cache_add_lru(page, lru);
- mem_cgroup_move_lists(page, lru);
put_page(page);
}
#endif /* CONFIG_UNEVICTABLE_LRU */
@@ -813,6 +811,7 @@ int __isolate_lru_page(struct page *page, int mode, int file)
return ret;
ret = -EBUSY;
+
if (likely(get_page_unless_zero(page))) {
/*
* Be careful not to clear PageLRU until after we're
@@ -821,6 +820,7 @@ int __isolate_lru_page(struct page *page, int mode, int file)
*/
ClearPageLRU(page);
ret = 0;
+ mem_cgroup_del_lru(page);
}
return ret;
@@ -1134,7 +1134,6 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
SetPageLRU(page);
lru = page_lru(page);
add_page_to_lru_list(zone, page, lru);
- mem_cgroup_move_lists(page, lru);
if (PageActive(page) && scan_global_lru(sc)) {
int file = !!page_is_file_cache(page);
zone->recent_rotated[file]++;
@@ -1263,7 +1262,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
ClearPageActive(page);
list_move(&page->lru, &zone->lru[lru].list);
- mem_cgroup_move_lists(page, lru);
+ mem_cgroup_add_lru_list(page, lru);
pgmoved++;
if (!pagevec_add(&pvec, page)) {
__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
@@ -2408,6 +2407,7 @@ retry:
__dec_zone_state(zone, NR_UNEVICTABLE);
list_move(&page->lru, &zone->lru[l].list);
+ mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l);
__inc_zone_state(zone, NR_INACTIVE_ANON + l);
__count_vm_event(UNEVICTABLE_PGRESCUED);
} else {
@@ -2416,6 +2416,7 @@ retry:
*/
SetPageUnevictable(page);
list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list);
+ mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE);
if (page_evictable(page, NULL))
goto retry;
}