On Fri, May 28, 2010 at 11:36:17AM -0300, Luis Claudio R. Goncalves wrote: > On Fri, May 28, 2010 at 11:06:23PM +0900, Minchan Kim wrote: > | On Fri, May 28, 2010 at 09:53:05AM -0300, Luis Claudio R. Goncalves wrote: > | > On Fri, May 28, 2010 at 02:59:02PM +0900, KOSAKI Motohiro wrote: > ... > | > | As far as my observation, RT-function always have some syscall. because pure > | > | calculation doesn't need deterministic guarantee. But _if_ you are really > | > | using such priority design. I'm ok maximum NonRT priority instead maximum > | > | RT priority too. > | > > | > I confess I failed to distinguish memcg OOM and system OOM and used "in > | > case of OOM kill the selected task the faster you can" as the guideline. > | > If the exit code path is short that shouldn't be a problem. > | > > | > Maybe the right way to go would be giving the dying task the biggest > | > priority inside that memcg to be sure that it will be the next process from > | > that memcg to be scheduled. Would that be reasonable? > | > | Hmm. I can't understand your point. > | What do you mean failing distinguish memcg and system OOM? > | > | We already have been distinguish it by mem_cgroup_out_of_memory. > | (but we have to enable CONFIG_CGROUP_MEM_RES_CTLR). > | So task selected in select_bad_process is one out of memcg's tasks when > | memcg have a memory pressure. > > The approach of giving the highest priority to the dying task makes sense > in a system wide OOM situation. I though that would also be good for the > memcg OOM case. > > After Balbir Singh's comment, I understand that in a memcg OOM the dying > task should have a priority just above the priority of the main task of > that memcg, in order to avoid interfering in the rest of the system. > > That is the point where I failed to distinguish between memcg and system OOM. > > Should I pursue that new idea of looking for the right priority inside the > memcg or is it overkill? I really don't have a clear view of the impact of > a memcg OOM on system performance - don't know if it is better to solve the > issue sooner (highest RT priority) or leave it to be solved later (highest > prio on the memcg). I have the impression the general case points to the > simpler solution. I think highest RT proirity ins't good solution. As I mentiond, Some RT functions don't want to be preempted by other processes which cause memory pressure. It makes RT task broken. On the other hand, normal processes don't have a requirement of RT. But it isn't a big problem that it lost little time slice, I think. So how about raising max normal priority? but I am not sure this is right solution. Let's listen other's opinion. I believe Peter have a good idea. > > Luis > -- > [ Luis Claudio R. Goncalves Bass - Gospel - RT ] > [ Fingerprint: 4FDD B8C4 3C59 34BD 8BE9 2696 7203 D980 A448 C8F8 ] > -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>