Re: [PATCH 3/5] oom: oom-killer don't use proportion of system-raminternally

From: KOSAKI Motohiro
Date: Mon May 23 2011 - 21:14:35 EST


Hi


@@ -476,14 +476,17 @@ static const struct file_operations proc_lstats_operations = {

static int proc_oom_score(struct task_struct *task, char *buffer)
{
- unsigned long points = 0;
+ unsigned long points;
+ unsigned long ratio = 0;
+ unsigned long totalpages = totalram_pages + total_swap_pages + 1;

Does we need +1?
oom_badness does have the check.

"ratio = points * 1000 / totalpages;" need to avoid zero divide.

/*
* Root processes get 3% bonus, just like the __vm_enough_memory()
* implementation used by LSMs.
+ *
+ * XXX: Too large bonus, example, if the system have tera-bytes memory..
*/
- if (has_capability_noaudit(p, CAP_SYS_ADMIN))
- points -= 30;
+ if (has_capability_noaudit(p, CAP_SYS_ADMIN)) {
+ if (points>= totalpages / 32)
+ points -= totalpages / 32;
+ else
+ points = 0;

Odd. Why do we initialize points with 0?

I think the idea is good.

The points is unsigned. It's common technique to avoid underflow.


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