Oren Laadan [orenl@xxxxxxxxxxxxxxx] wrote: | Sukadev Bhattiprolu wrote: | > | > Secondly, isn't pids_nr same as tasks_nr ? If so do we need both ? | | As the comment says: one is used exclusively for checkpoint and the | other exclusively for restart. | So we don't strictly need both. I thought that for readability of it's | useful to have @pids_nr (ok, @nr_pids ...) when dealing with a @pids_arr, | and a @tasks_nr (ok .. @nr_tasks ...) when dealing with @tasks_arr. | | > | > Or is this intended to address the issue of multiple pid_nr values that a | > task in a nested container can have ? If so, pids_nr is > tasks_nr and that | > brings up two comments :-) | | Ugh. This topic is TBD. | | > | > First, mktree.c and cr_next_task() are using 'ctx->pids_nr' to determine how | > many tasks to start. If we are talking about nested containers, pids_nr | > will be greater than tasks_nr so, mktree and cr_next_task() should be | > use 'ctx->tasks_nr' to determine how many tasks to create. Also if | > checkpointing a nested container we should view the multiple nested pid | > values a process as an attribute of the task and maybe save them in | > cr_write_task() rather than in cr_write_tree(). | | Lol .. who's talking about nested containers ? ;) :-) I guess the presence of both pids_nr and tasks_nr in the same structure threw me off. Yes, ignoring nested containers for now is really good :-) Maybe we can add a check in cr_may_checkpoint() to fail if any task in the process tree has : pid->level != task_pid(current)->level + 1 so nested containers fail cleanly. | | (seriously: I'm not considering that now; my gut feeling is that it may | be useful to do pid_ns in userspace, like task creation - and in that | case it makes sense to keep it in cr_write_tree(). then again, I have | not looked at it in depth). | | > | > My second comment is more an orthogonal question. Suppose init_pid_ns = level | > 0 and we have a container that is nested at level 3. If we checkpoint just | > this container, we would want to be able to restore this container at any level | > 0 right ? | | True. Do you see any limitation in the current code that prevents this ? No I did not see anything. I mentioned it because the the number of pids associated with the task will change and we have to discard some pids during restart. But lets not worry about it now :-) Sukadev _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
