On Fri, 11 Jul 2008 09:20:58 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > Thank you for your effort. > > On Wed, 9 Jul 2008 23:46:33 -0700 > "Paul Menage" <menage@xxxxxxxxxx> wrote: > > 3) memory > > > > Curently the memory cgroup only uses the mm->owner's cgroup at charge > > time, and keeps a reference to the cgroup on the page. However, > > patches have been proposed that would move all non-shared (page count > > == 1) pages to the destination cgroup when the mm->owner moves to a > > new cgroup. Since it's not possible to prevent page count changes > > without locking all mms on the system, even this transaction approach > > can't really give guarantees. However, something like the following > > would probably be suitable. It's very similar to the memrlimit > > approach, except for the fact that we have to handle the fact that the > > number of pages we finally move might not be exactly the same as the > > number of pages we thought we'd be moving. > > > > prepare_attach_sleep() { > > down_read(&mm->mmap_sem); > > if (mm->owner != state->task) return 0; > > count = count_unshared_pages(mm); > > // save the count charged to the new cgroup > > state->subsys[memcgroup_subsys_id] = (void *)count; > > if ((ret = res_counter_charge(state->dest, count)) { > > up_read(&mm->mmap_sem); > > } > > return ret; > > } > > > > commit_attach() { > > if (mm->owner == state->task) { > > final_count = move_unshared_pages(mm, state->dest); > > res_counter_uncharge(state->src, final_count); > > count = state->subsys[memcgroup_subsys_id]; > > res_counter_force_charge(state->dest, final_count - count); > > } > > up_read(&mm->mmap_sem); > > } > > > > abort_attach_sleep() { > > if (mm->owner == state->task) { > > count = state->subsys[memcgroup_subsys_id]; > > res_counter_uncharge(state->dest, count); > > } > > up_read(&mm->mmap_sem); > > } > > > > At frist look, maybe works well. we need some special codes (to move resource) > but that's all. > > My small concern is a state change between prepare_attach_sleep() -> > commit_attach(). Hmm...but as you say, we cannot do down_write(mmap_sem). > Maybe inserting some check codes to mem_cgroup_charge() to stop charge while > move is the last thing we can do. > I have two comments. - I think page reclaiming code decreases the memory charge without holding mmap_sem(e.g. try_to_unmap(), __remove_mapping()). Shouldn't we handle these cases? - When swap controller is merged, I should implement prepare_attach_nosleep() which holds swap_lock. > Anyway, if unwinding is supported officially, I think we can find a way > to go. > I think so too. Thanks, Daisuke Nishimura. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers