On Tue, 8 Feb 2011 11:13:51 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> On Mon, 7 Feb 2011 18:13:22 -0800 (PST)
> David Rientjes <rientjes@xxxxxxxxxx> wrote:
>
> > On Tue, 8 Feb 2011, KAMEZAWA Hiroyuki wrote:
> >
> > > > +static int mem_cgroup_oom_delay_millisecs_write(struct cgroup *cgrp,
> > > > + struct cftype *cft, u64 val)
> > > > +{
> > > > + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> > > > + struct mem_cgroup *iter;
> > > > +
> > > > + if (val > MAX_SCHEDULE_TIMEOUT)
> > > > + return -EINVAL;
> > > > +
> > > > + for_each_mem_cgroup_tree(iter, memcg) {
> > > > + iter->oom_delay = msecs_to_jiffies(val);
> > > > + memcg_oom_recover(iter);
> > > > + }
> > > > + return 0;
> > >
> > > Seems nicer and it seems you tries to update all children cgroups.
> > >
> > > BTW, with above code, with following heirarchy,
> > >
> > > A
> > > /
> > > B
> > > /
> > > C
> > >
> > > When a user set oom_delay in order as A->B->C, A,B,C can have 'different' numbers.
> > > When a user set oom_delay in order as C->B->A, A,B,C will have the same numbers.
> > >
> > > This intreface seems magical, or broken.
> > >
> >
> > It's not really magical, it just means that if you change the delay for a
> > memcg that you do so for all of its children implicitly as well.
> >
> But you didn't explain the bahavior in Documenation.
>
And write this fact:
A
/
B
/
C
When
A.memory_oom_delay=1sec.
B.memory_oom_delay=500msec
C.memory_oom_delay=200msec
If there are OOM in group C, C's oom_kill will be delayed for 200msec and
a task in group C will be killed.
If there are OOM in group B, B's oom_kill will be delayed for 200msec and
a task in group B or C will be killed.
If there are OOM in group A, A's oom_kill will be delayed for 1sec and
a task in group A,B or C will be killed.
oom_killer in the hierarchy is serialized by lock and happens one-by-one
for avoiding a serial kill. So, above delay can be stacked.
Thanks,
-Kame
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