On Thu 16-05-13 08:28:33, Konstantin Khlebnikov wrote: > Michal Hocko wrote: > >On Wed 15-05-13 16:35:08, Konstantin Khlebnikov wrote: > >>Sha Zhengju wrote: > >>>Hi, > >>> > >>>This is my second attempt to make memcg page stat lock simpler, the > >>>first version: http://www.spinics.net/lists/linux-mm/msg50037.html. > >>> > >>>In this version I investigate the potential race conditions among > >>>page stat, move_account, charge, uncharge and try to prove it race > >>>safe of my proposing lock scheme. The first patch is the basis of > >>>the patchset, so if I've made some stupid mistake please do not > >>>hesitate to point it out. > >> > >>I have a provocational question. Who needs these numbers? I mean > >>per-cgroup nr_mapped and so on. > > > >Well, I guess it makes some sense to know how much page cache and anon > >memory is charged to the group. I am using that to monitor the per-group > >memory usage. I can imagine a even better coverage - something > >/proc/meminfo like. > > > > I think page counters from lru-vectors can give enough information for that. not for dirty and writeback data which is the next step. > If somebody needs more detailed information there are enough ways to get it. > Amount of mapped pages can be estimated via summing rss counters from mm-structs. > Exact numbers can be obtained via examining /proc/pid/pagemap. How do you find out whether given pages were charged to the group of interest - e.g. shared data or taks that has moved from a different group without move_at_immigrate? > I don't think that simulating 'Mapped' line in /proc/mapfile is a worth reason > for adding such weird stuff into the rmap code on map/unmap paths. The accounting code is trying to be not intrusive as much as possible. This patchset makes it more complicated without a good reason and that is why it has been Nacked by me. -- Michal Hocko SUSE Labs -- 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>