Here is a follow up for this patch. As I've mentioned in the other
email, I would like to mark oom victim in the mm_struct but that
requires more changes and the patch simplifies select_bad_process
nicely already so I like this patch even now.
---
>From 06fc6821e581f82fb186770d84f5ee28f9fe18c3 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@xxxxxxxx>
Date: Fri, 20 May 2016 09:45:05 +0200
Subject: [PATCH] mmotm: mmoom-speed-up-select_bad_process-loop-fix
Do not blow the signal_struct size. pahole -C signal_struct says:
struct signal_struct {
atomic_t sigcnt; /* 0 4 */
atomic_t live; /* 4 4 */
int nr_threads; /* 8 4 */
/* XXX 4 bytes hole, try to pack */
struct list_head thread_head; /* 16 16 */
So we can stick the new counter after nr_threads and keep the size
of the structure on 64b.
While we are at it also remove the thread_group_leader check from
select_bad_process because it is not really needed as we are iterating
processes rather than threads.
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
---
include/linux/sched.h | 2 +-
mm/oom_kill.c | 3 ---
2 files changed, 1 insertion(+), 4 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 65b9d3807b1b..e137fa6db049 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -660,6 +660,7 @@ struct signal_struct {
atomic_t sigcnt;
atomic_t live;
int nr_threads;
+ atomic_t oom_victims; /* # of TIF_MEDIE threads in this thread group */
struct list_head thread_head;
wait_queue_head_t wait_chldexit; /* for wait4() */
@@ -781,7 +782,6 @@ struct signal_struct {
struct tty_audit_buf *tty_audit_buf;
#endif
- atomic_t oom_victims; /* # of TIF_MEDIE threads in this thread group */
oom_flags_t oom_flags;
short oom_score_adj; /* OOM kill score adjustment */
short oom_score_adj_min; /* OOM kill score adjustment min value.
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 8e151d018d65..5bb2f7698ad7 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -327,9 +327,6 @@ static struct task_struct *select_bad_process(struct oom_control *oc,
points = oom_badness(p, NULL, oc->nodemask, totalpages);
if (!points || points < chosen_points)
continue;
- /* Prefer thread group leaders for display purposes */
- if (points == chosen_points && thread_group_leader(chosen))
- continue;
chosen = p;
chosen_points = points;
--
2.8.1
--
Michal Hocko
SUSE Labs
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