Messages in this thread | | | Date | Tue, 10 Mar 2009 15:03:45 +0000 | Subject | Re: cgroup, balance RT bandwidth | From | Rolando Martins <> |
| |
On Tue, Mar 10, 2009 at 2:26 PM, Peter Zijlstra <peterz@infradead.org> wrote: > On Tue, 2009-03-10 at 11:49 +0000, Rolando Martins wrote: >> Just to confirm, cpuset.sched_load_balance doesn't work with RT, right? > > It should. It should split the RT balance domain just the same. > >> You cannot have tasks for sub-domain 2 to utilize bandwidth of >> sub-domain 3, right? > > If you disabled load-balancing on your root domain (1 below) then > indeed, tasks from 2 will not be able to consume bandwidth from tasks in > 3. > > The available bandwidth is related to the number of cpus in the balance > domain.
cgroup echo 1 > cpuset.sched_load_balance
cgroup/2 echo 0 > cpuset.mems echo 0-2 > cpuset.cpus echo 450000 > cpu.rt_runtime_us
cgroup/3 echo 0 > cpuset.mems echo 3 > cpuset.cpus echo 450000 > cpu.rt_runtime_us
I have a small test that uses a loop to utilize 100% cpu (SCHED_FIFO). When I run 2 tests on cgroup/3, it only uses bandwidth from cpu 3 (100%), the balancing isn't happening. As I use the SCHED_FIFO, the 2 processes run sequentially.
Can you check this? Maybe I am doing something wrong...
> >> >> __1__ >> / \ >> 2 3 >> (50% rt) (50% rt ) >> >> For my application domain it would be interesting to have >> rt_runtime_ns as a min. of allocated rt and not a max. > >> Ex. If an application of domain 2 needs to go up to 100% and domain 3 >> is idle, then it would be cool to let it utilize the full bandwidth. > >> (we also could have a hard upper limit in each sub-domain, like >> hard_up=0.8, i.e. even if we could get 100%, we will only utilize >> 80%); in other words, rt having the same cpu bandwidth management behavior >> as the "best-effort" tasks. >> >> Could this be done? > > Possibly, but since RT scheduling is all about determinism, I see no use > in adding something best-effort -- that simply defeats the purpose. > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |