On Tue, Oct 23, 2007 at 09:41:49AM -0700, Paul Menage wrote: > > > Adds a cpu.usage file to the CFS cgroup that reports CPU usage in > > > milliseconds for that cgroup's tasks > > > > It would be nice to split this into user and sys time at some point. > > Sounds reasonable - but does CFS track this?
No, not for a group. We could extend account_user_time() and account_systime_time() in this regard. > > We have also received request to provide idle time for a > > container/cgroup. > > The semantics of "idle time" for a cgroup on a shared system seem a > bit fuzzy. How would you define it? I think the percentage of time when it didn't have any runnable task in its runqueues. > Suppose you have two cgroups that would each want to use, say, 55% of > a CPU - technically they should each be regarded as having 45% idle > time, but if they run on a the same CPU the chances are that they will > both always have some processes on their runqueue due to contention > with the other group. So how would you measure the difference between > this and a cgroup that really is trying to use 100%? Good point. I think we need to subtract out the time it was waiting on runqueue when calculating idle time. |------- . . . . . . ---------zzzzzzzzzzzz.......-----------| t0 t1 t2 t3 t4 t5 t6 ---- -> Running time .... -> Waiting time (to get on the cpu) zzzz -> Sleeping time (when it didnt want to run because of lack of tasks) So, in this case, idle time = (t4 - t3) / [ (t6 - t1) - (t2-t1) - (t5-t4) ? This idle time will be a per-cpu stat for every cgroup and needs to be consolidated across cpus into a single idle-stat number, just like how top does it. -- 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/