> On Tue, 10 Jun 2008 14:50:32 +0900 (JST) > yamamoto@xxxxxxxxxxxxx (YAMAMOTO Takashi) wrote: > > > > 3. Use Lazy Manner > > > When the task moves, we can mark the pages used by it as > > > "Wrong Charge, Should be dropped", and add them some penalty in the LRU. > > > Pros. > > > - no complicated ones. > > > - the pages will be gradually moved at memory pressure. > > > Cons. > > > - A task's usage can exceed the limit for a while. > > > - can't handle mlocked() memory in proper way. > > > > > > 4. Allow Half-moved state and abandon rollback. > > > Pros. > > > - no complicated ones in the code. > > > Cons. > > > - the users will be in chaos. > > > > how about: > > > > 5. try to move charges as your patch does. > > if the target cgroup's usage is going to exceed the limit, > > try to shrink it. if it failed, just leave it exceeded. > > (ie. no rollback) > > for the memory subsystem, which can use its OOM killer, > > the failure should be rare. > > > > Hmm, allowing exceed and cause OOM kill ? > > One difficult point is that the users cannot know they can move task > without any risk. How to handle the risk can be a point. > I don't like that approarch in general because I don't like "exceed" > status. But implementation will be easy. regardless of how to handle task moves, it's important to provide information to help users to avoid unreasonable cgroup/task placement. otherwise, they will be surprised by OOM-killer etc anyway. having said that, if you decide to put too large tasks into a cgroup with too small limit, i don't think that there are many choices besides OOM-kill and allowing "exceed". actually, i think that #3 and #5 are somewhat similar. a big difference is that, while #5 shrinks the cgroup immediately, #3 does it later. in case we need to do OOM-kill, i prefer to do it sooner than later. > > > After writing this patch, for me, "3" is attractive. now. > > > (or using Lazy manner and allow moving of usage instead of freeing it.) > > > > > > One reasone is that I think a typical usage of memory controller is > > > fork()->move->exec(). (by libcg ?) and exec() will flush the all usage. > > > > i guess that moving long-running applications can be desirable > > esp. for not so well-designed systems. > > > > hmm, for not so well-designed systems....true. > But "5" has the same kind of risks for not so well-desgined systems ;) i don't claim that #5 is a perfect solution for everyone. :) YAMAMOTO Takashi _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers