Hello,
在 2023/8/17 10:07, Alexei Starovoitov 写道:
On Thu, Aug 10, 2023 at 1:13 AM Chuyi Zhou <zhouchuyi@xxxxxxxxxxxxx> wrote:
static int oom_evaluate_task(struct task_struct *task, void *arg)
{
struct oom_control *oc = arg;
@@ -317,6 +339,26 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
if (!is_memcg_oom(oc) && !oom_cpuset_eligible(task, oc))
goto next;
+ /*
+ * If task is allocating a lot of memory and has been marked to be
+ * killed first if it triggers an oom, then select it.
+ */
+ if (oom_task_origin(task)) {
+ points = LONG_MAX;
+ goto select;
+ }
+
+ switch (bpf_oom_evaluate_task(task, oc)) {
+ case BPF_EVAL_ABORT:
+ goto abort; /* abort search process */
+ case BPF_EVAL_NEXT:
+ goto next; /* ignore the task */
+ case BPF_EVAL_SELECT:
+ goto select; /* select the task */
+ default:
+ break; /* No BPF policy */
+ }
+
I think forcing bpf prog to look at every task is going to be limiting
long term.
It's more flexible to invoke bpf prog from out_of_memory()
and if it doesn't choose a task then fallback to select_bad_process().
I believe that's what Roman was proposing.
bpf can choose to iterate memcg or it might have some side knowledge
that there are processes that can be set as oc->chosen right away,
so it can skip the iteration.
IIUC, We may need some new bpf features if we want to iterating
tasks/memcg in BPF, sush as:
bpf_for_each_task
bpf_for_each_memcg
bpf_for_each_task_in_memcg
...
It seems we have some work to do first in the BPF side.
Will these iterating features be useful in other BPF scenario except OOM
Policy?
Thanks.
