On Tue, Aug 21 2012, Michal Hocko wrote: > On Tue 21-08-12 13:22:09, Glauber Costa wrote: >> On 08/21/2012 11:54 AM, Michal Hocko wrote: > [...] >> > But maybe you have a good use case for that? >> > >> Honestly, I don't. For my particular use case, this would be always on, >> and end of story. I was operating under the belief that being able to >> say "Oh, I regret", and then turning it off would be beneficial, even at >> the expense of the - self contained - complication. >> >> For the general sanity of the interface, it is also a bit simpler to say >> "if kmem is unlimited, x happens", which is a verifiable statement, than >> to have a statement that is dependent on past history. > > OK, fair point. We shouldn't rely on the history. Maybe > memory.kmem.limit_in_bytes could return some special value like -1 in > such a case? > >> But all of those need of course, as you pointed out, to be traded off >> by the code complexity. >> >> I am fine with either, I just need a clear sign from you guys so I don't >> keep deimplementing and reimplementing this forever. > > I would be for make it simple now and go with additional features later > when there is a demand for them. Maybe we will have runtimg switch for > user memory accounting as well one day. > > But let's see what others think? In my use case memcg will either be disable or (enabled and kmem limiting enabled). I'm not sure I follow the discussion about history. Are we saying that once a kmem limit is set then kmem will be accounted/charged to memcg. Is this discussion about the static branches/etc that are autotuned the first time is enabled? The first time its set there parts of the system will be adjusted in such a way that may impose a performance overhead (static branches, etc). Thereafter the performance cannot be regained without a reboot. This makes sense to me. Are we saying that kmem.limit_in_bytes will have three states? - kmem never enabled on machine therefore kmem has never been enabled - kmem has been enabled in past but is not effective is this cgroup (limit=infinity) - kmem is effective in this mem (limit=not-infinity) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>