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authorJohannes Weiner2012-01-12 17:18:02 -0800
committerLinus Torvalds2012-01-12 20:13:05 -0800
commitad2b8e601099a23dffffb53f91c18d874fe98854 (patch)
tree6b7706f3005fd799f23d0ddc21fe5b33fd1e79ac /mm
parent5660048ccac8735d9bc0a46325a02e6a6518b5b2 (diff)
mm: memcg: remove optimization of keeping the root_mem_cgroup LRU lists empty
root_mem_cgroup, lacking a configurable limit, was never subject to limit reclaim, so the pages charged to it could be kept off its LRU lists. They would be found on the global per-zone LRU lists upon physical memory pressure and it made sense to avoid uselessly linking them to both lists. The global per-zone LRU lists are about to go away on memcg-enabled kernels, with all pages being exclusively linked to their respective per-memcg LRU lists. As a result, pages of the root_mem_cgroup must also be linked to its LRU lists again. This is purely about the LRU list, root_mem_cgroup is still not charged. The overhead is temporary until the double-LRU scheme is going away completely. Signed-off-by: Johannes Weiner <jweiner@redhat.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Ying Han <yinghan@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c12
1 files changed, 2 insertions, 10 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 750ed1449955..ad7f36f676ff 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1031,8 +1031,6 @@ void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
/* huge page split is done under lru_lock. so, we have no races. */
MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page);
- if (mem_cgroup_is_root(pc->mem_cgroup))
- return;
VM_BUG_ON(list_empty(&pc->lru));
list_del_init(&pc->lru);
}
@@ -1057,13 +1055,11 @@ void mem_cgroup_rotate_reclaimable_page(struct page *page)
return;
pc = lookup_page_cgroup(page);
- /* unused or root page is not rotated. */
+ /* unused page is not rotated. */
if (!PageCgroupUsed(pc))
return;
/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
smp_rmb();
- if (mem_cgroup_is_root(pc->mem_cgroup))
- return;
mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
list_move_tail(&pc->lru, &mz->lists[lru]);
}
@@ -1077,13 +1073,11 @@ void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
return;
pc = lookup_page_cgroup(page);
- /* unused or root page is not rotated. */
+ /* unused page is not rotated. */
if (!PageCgroupUsed(pc))
return;
/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
smp_rmb();
- if (mem_cgroup_is_root(pc->mem_cgroup))
- return;
mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
list_move(&pc->lru, &mz->lists[lru]);
}
@@ -1115,8 +1109,6 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
/* huge page split is done under lru_lock. so, we have no races. */
MEM_CGROUP_ZSTAT(mz, lru) += 1 << compound_order(page);
SetPageCgroupAcctLRU(pc);
- if (mem_cgroup_is_root(pc->mem_cgroup))
- return;
list_add(&pc->lru, &mz->lists[lru]);
}