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authorDavid Rientjes <rientjes@google.com>2012-05-29 15:06:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-29 16:22:24 -0700
commita7f638f999ff42310e9582273b1fe25ea6e469ba (patch)
tree174dec4d849b78023a23a15d5947cf1d3be9f564 /fs/proc
parentfe35004fbf9eaf67482b074a2e032abb9c89b1dd (diff)
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mm, oom: normalize oom scores to oom_score_adj scale only for userspace
The oom_score_adj scale ranges from -1000 to 1000 and represents the proportion of memory available to the process at allocation time. This means an oom_score_adj value of 300, for example, will bias a process as though it was using an extra 30.0% of available memory and a value of -350 will discount 35.0% of available memory from its usage. The oom killer badness heuristic also uses this scale to report the oom score for each eligible process in determining the "best" process to kill. Thus, it can only differentiate each process's memory usage by 0.1% of system RAM. On large systems, this can end up being a large amount of memory: 256MB on 256GB systems, for example. This can be fixed by having the badness heuristic to use the actual memory usage in scoring threads and then normalizing it to the oom_score_adj scale for userspace. This results in better comparison between eligible threads for kill and no change from the userspace perspective. Suggested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Tested-by: Dave Jones <davej@redhat.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/base.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index d2d3108a611c..d7d711876b6a 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -411,12 +411,13 @@ static const struct file_operations proc_lstats_operations = {
static int proc_oom_score(struct task_struct *task, char *buffer)
{
+ unsigned long totalpages = totalram_pages + total_swap_pages;
unsigned long points = 0;
read_lock(&tasklist_lock);
if (pid_alive(task))
- points = oom_badness(task, NULL, NULL,
- totalram_pages + total_swap_pages);
+ points = oom_badness(task, NULL, NULL, totalpages) *
+ 1000 / totalpages;
read_unlock(&tasklist_lock);
return sprintf(buffer, "%lu\n", points);
}