I think maybe I didnt communicate what I mean by a container here (although I thought I did). I am referring to a container in a vserver context (set of tasks which share the same namespace).
On Fri, Mar 09, 2007 at 02:09:35PM -0800, Paul Menage wrote: > >2. Regarding space savings, if 100 tasks are in a container (I dont know > > what is a typical number) -and- lets say that all tasks are to share > > the same resource allocation (which seems to be natural), then having > > a 'struct container_group *' pointer in each task_struct seems to be not > > very efficient (simply because we dont need that task-level granularity > > of > > managing resource allocation). > > I think you should re-read my patches. > > Previously, each task had N pointers, one for its container in each > potential hierarchy. The container_group concept means that each task > has 1 pointer, to a set of container pointers (one per hierarchy) > shared by all tasks that have exactly the same set of containers (in > the various different hierarchies). Ok, let me see if I can convey what I had in mind better: uts_ns pid_ns ipc_ns \ | / --------------- | nsproxy | ---------------- / | \ \ <-- 'nsproxy' pointer T1 T2 T3 ...T1000 | | | | <-- 'containers' pointer (4/8 KB for 1000 task) ------------------- | container_group | ------------------ / ---------- | container | ---------- | ---------- | cpu_limit | ---------- (T1, T2, T3 ..T1000) are part of a vserver lets say sharing the same uts/pid/ipc_ns. Now where do we store the resource control information for this unit/set-of-tasks in your patches? (tsk->containers->container[cpu_ctlr.hierarchy] + X)->cpu_limit (The X is to account for the fact that cotainer structure points to a 'struct container_subsys_state' embedded in some other structure. Its usually zero if the structure is embedded at the top) I understand that container_group also points directly to 'struct container_subsys_state', in which case, the above is optimized to: (tsk->containers->subsys[cpu_ctlr.subsys_id] + X)->cpu_limit Did I get that correct? Compare that to: ----------- | cpu_limit | uts_ns pid_ns ipc_ns ---------- \ | / | ------------------------ | nsproxy | ------------------------ / | \ | T1 T2 T3 .....T1000 We save on 4/8 KB (for 1000 tasks) by avoiding the 'containers' pointer in each task_struct (just to get to the resource limit information). So my observation was (again note primarily from a vserver context): given that (T1, T2, T3 ..T1000) will all need to be managed as a unit (because they are all sharing the same nsproxy pointer), then having the '->containers' pointer in -each- one of them to tell the unit's limit is not optimal. Instead store the limit in the proper unit structure (in this case nsproxy - but whatever else is more suitable vserver datastructure (pid_ns?) which represent the fundamental unit of res mgmt in vservers). (I will respond to remaining comments later ..too early in the morning now!) -- Regards, vatsa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/