On Fri, 13 May 2011, KOSAKI Motohiro wrote: > > > Yes, I'm sure we'll still have additional discussion when KOSAKI-san > > > replies to my review of his patchset, so this quick patch was written only > > > for CAI's testing at this point. > > > > > > In reference to the above, I think that giving root processes a 3% bonus > > > at all times may be a bit aggressive. As mentioned before, I don't think > > > that all root processes using 4% of memory and the remainder of system > > > threads are using 1% should all be considered equal. At the same time, I > > > do not believe that two threads using 50% of memory should be considered > > > equal if one is root and one is not. So my idea was to discount 1% for > > > every 30% of memory that a root process uses rather than a strict 3%. > > > > > > That change can be debated and I think we'll probably settle on something > > > more aggressive like 1% for every 10% of memory used since oom scores are > > > only useful in comparison to other oom scores: in the above scenario where > > > there are two threads, one by root and one not by root, using 50% of > > > memory each, I think it would be legitimate to give the root task a 5% > > > bonus so that it would only be selected if no other threads used more than > > > 44% of memory (even though the root thread is truly using 50%). > > > > > > This is a heuristic within the oom killer badness scoring that can always > > > be debated back and forth, but I think a 1% bonus for root processes for > > > every 10% of memory used is plausible. > > > > > > Comments? > > > > Yes. Tend to agree. > > Apparently, absolute 3% bonus is a problem in CAI's case. > > > > Your approach which makes bonus with function of rss is consistent > > with current OOM heuristic. > > So In consistency POV, I like it as it could help deterministic OOM policy. > > > > About 30% or 10% things, I think it's hard to define a ideal magic > > value for handling for whole workloads. > > It would be very arguable. So we might need some standard method to > > measure it/or redhat/suse peoples. Anyway, I don't want to argue it > > until we get a number. > > I have small comments. 1) typical system have some small size system daemon > 2) David's points -= 100 * (points / 3000); line doesn't make any bonus if > points is less than 3000. With the 1% bonus per 10% memory consumption, it would be points -= 100 * (points / 1000); instead. So, yes, this wouldn't give any bonus for root tasks that use 10% of allowed memory or less. > Zero root bonus is really desired? It may lead to > kill system daemon at first issue. I would think of it this way: if a root task is using 9% of available memory and that happens to be the largest consumer of memory, then it makes sense to kill it instead of killing other smaller non-root tasks. The 3% bonus would have killed the task if all other threads are using 6% or less, this just allows them to use 2% more memory now. On the other hand, if a root task is using 50% of available memory, then a 45% non-root task would be sacrificed instead. Perhaps we need to be more aggressive and give more of a bonus to root tasks? -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>