path: root/mm/thrash.c
diff options
authorKOSAKI Motohiro <>2011-06-15 15:08:15 -0700
committerLinus Torvalds <>2011-06-15 20:03:59 -0700
commitd7911ef30cb7bec52234c2b7a5c275ac8f07905a (patch)
treec3d9dc8ffc5d9478da434faecc27759ee34edf83 /mm/thrash.c
parent83cd81a34357a632509f7491eec81e62e71d65f7 (diff)
vmscan: implement swap token priority aging
While testing for memcg aware swap token, I observed a swap token was often grabbed an intermittent running process (eg init, auditd) and they never release a token. Why? Some processes (eg init, auditd, audispd) wake up when a process exiting. And swap token can be get first page-in process when a process exiting makes no swap token owner. Thus such above intermittent running process often get a token. And currently, swap token priority is only decreased at page fault path. Then, if the process sleep immediately after to grab swap token, the swap token priority never be decreased. That's obviously undesirable. This patch implement very poor (and lightweight) priority aging. It only be affect to the above corner case and doesn't change swap tendency workload performance (eg multi process qsbench load) Signed-off-by: KOSAKI Motohiro <> Reviewed-by: Rik van Riel <> Reviewed-by: KAMEZAWA Hiroyuki <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/thrash.c')
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/thrash.c b/mm/thrash.c
index 17d9e29e4c9c..fabf2d0f5169 100644
--- a/mm/thrash.c
+++ b/mm/thrash.c
@@ -25,10 +25,13 @@
#include <trace/events/vmscan.h>
static DEFINE_SPINLOCK(swap_token_lock);
struct mm_struct *swap_token_mm;
struct mem_cgroup *swap_token_memcg;
static unsigned int global_faults;
+static unsigned int last_aging;
static struct mem_cgroup *swap_token_memcg_from_mm(struct mm_struct *mm)
@@ -64,6 +67,11 @@ void grab_swap_token(struct mm_struct *mm)
if (!swap_token_mm)
goto replace_token;
+ if ((global_faults - last_aging) > TOKEN_AGING_INTERVAL) {
+ swap_token_mm->token_priority /= 2;
+ last_aging = global_faults;
+ }
if (mm == swap_token_mm) {
mm->token_priority += 2;
goto update_priority;
@@ -81,7 +89,7 @@ void grab_swap_token(struct mm_struct *mm)
goto replace_token;
- trace_update_swap_token_priority(mm, old_prio);
+ trace_update_swap_token_priority(mm, old_prio, swap_token_mm);
mm->faultstamp = global_faults;
@@ -94,6 +102,7 @@ replace_token:
trace_replace_swap_token(swap_token_mm, mm);
swap_token_mm = mm;
swap_token_memcg = swap_token_memcg_from_mm(mm);
+ last_aging = global_faults;
goto out;