[mmotm][PATCH 2/4] oom: make oom_score to per-process value

From: KOSAKI Motohiro
Date: Wed Aug 26 2009 - 05:35:36 EST


oom-killer kill a process, not task. Then oom_score should be
calculated as per-process too. it makes consistency more and
makes speed up select_bad_process().

Cc: Paul Menage <menage@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
---
Documentation/filesystems/proc.txt | 2 +-
fs/proc/base.c | 2 +-
mm/oom_kill.c | 35 +++++++++++++++++++++++++++++------
3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index c97c430..2f17eee 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -1207,7 +1207,7 @@ The following heuristics are then applied:
* if the task was reniced, its score doubles
* superuser or direct hardware access tasks (CAP_SYS_ADMIN, CAP_SYS_RESOURCE
or CAP_SYS_RAWIO) have their score divided by 4
- * if oom condition happened in one cpuset and checked task does not belong
+ * if oom condition happened in one cpuset and checked process does not belong
to it, its score is divided by 8
* the resulting score is multiplied by two to the power of oom_adj, i.e.
points <<= oom_adj when it is positive and
diff --git a/fs/proc/base.c b/fs/proc/base.c
index fbf8788..0c1757c 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -448,7 +448,7 @@ static int proc_oom_score(struct task_struct *task, char *buffer)

do_posix_clock_monotonic_gettime(&uptime);
read_lock(&tasklist_lock);
- points = badness(task, uptime.tv_sec);
+ points = badness(task->group_leader, uptime.tv_sec);
read_unlock(&tasklist_lock);
return sprintf(buffer, "%lu\n", points);
}
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 55dcadd..26725bc 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -34,6 +34,23 @@ int sysctl_oom_dump_tasks;
static DEFINE_SPINLOCK(zone_scan_lock);
/* #define DEBUG */

+/*
+ * Is all threads of the target process nodes overlap ours?
+ */
+static int has_intersects_mems_allowed(struct task_struct *tsk)
+{
+ struct task_struct *t;
+
+ t = tsk;
+ do {
+ if (cpuset_mems_allowed_intersects(current, t))
+ return 1;
+ t = next_thread(t);
+ } while (t != tsk);
+
+ return 0;
+}
+
/**
* badness - calculate a numeric value for how bad this task has been
* @p: task struct of which task we should calculate
@@ -59,6 +76,9 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
struct mm_struct *mm;
struct task_struct *child;
int oom_adj = p->signal->oom_adj;
+ struct task_cputime task_time;
+ unsigned long utime;
+ unsigned long stime;

if (oom_adj == OOM_DISABLE)
return 0;
@@ -106,8 +126,11 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
* of seconds. There is no particular reason for this other than
* that it turned out to work very well in practice.
*/
- cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime))
- >> (SHIFT_HZ + 3);
+ thread_group_cputime(p, &task_time);
+ utime = cputime_to_jiffies(task_time.utime);
+ stime = cputime_to_jiffies(task_time.stime);
+ cpu_time = (utime + stime) >> (SHIFT_HZ + 3);
+

if (uptime >= p->start_time.tv_sec)
run_time = (uptime - p->start_time.tv_sec) >> 10;
@@ -148,7 +171,7 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
* because p may have allocated or otherwise mapped memory on
* this node before. However it will be less likely.
*/
- if (!cpuset_mems_allowed_intersects(current, p))
+ if (!has_intersects_mems_allowed(p))
points /= 8;

/*
@@ -204,13 +227,13 @@ static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
static struct task_struct *select_bad_process(unsigned long *ppoints,
struct mem_cgroup *mem)
{
- struct task_struct *g, *p;
+ struct task_struct *p;
struct task_struct *chosen = NULL;
struct timespec uptime;
*ppoints = 0;

do_posix_clock_monotonic_gettime(&uptime);
- do_each_thread(g, p) {
+ for_each_process(p) {
unsigned long points;

/*
@@ -263,7 +286,7 @@ static struct task_struct *select_bad_process(unsigned long *ppoints,
chosen = p;
*ppoints = points;
}
- } while_each_thread(g, p);
+ }

return chosen;
}
--
1.6.2.5



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