On 07/29/2013 04:07 PM, Peter Zijlstra wrote: > On Mon, Jul 29, 2013 at 02:25:33PM +0200, Holger Brunck wrote: >> On 07/23/2013 05:56 PM, Tejun Heo wrote: >>>> On 06/27/2013 07:17 PM, Holger Brunck wrote: >>>> >>>> On a single ARM CPU (kirkwood) I see the same confusing results similar to the >>>> results of the above powerpc example: >>>> >>>> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND >>>> 232 root 20 0 1924 492 420 R 99.9 0.4 0:29.15 dd >>>> 234 root 20 0 1924 492 420 R 0.3 0.4 0:00.13 dd >>>> >>>> I doublechecked this on my local host x86_64 multicore and here it works fine >>>> even if I force both dd processes to run on the same CPU: >>>> >>>> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND >>>> 32046 root 20 0 102m 516 432 R 49.4 0.0 0:32.49 dd >>>> 32049 root 20 0 102m 516 432 R 49.4 0.0 0:13.39 dd >>>> >>>> So either it's a problem for single CPUs or it's not allowed at all and works >>>> only by chance. >>> >>> Can you please boot with maxcpus=1 and see whether that makes the >>> issue reproducible on x86? >>> >> >> I retested this with maxcpus=0 to disable SMP completely and it works, both >> processes share 50% of the CPU. But I have to admit that I currently have only a >> 3.4 setup for my x86_64 PC. >> >> My setup for an arm kirkwood board and a board with a powerpc 8247 runs latest >> 3.10 kernel where I see the problem that one process is starving. But the >> problem was already present in a 3.0.x kernel. So it seems to be a architecture >> dependent problem. > > Does the below fix it? > no, unfortunately I got the same results as before. Two sched_idle task in the root group: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 622 root 20 0 1924 492 420 R 49.8 0.4 0:20.26 dd 623 root 20 0 1924 492 420 R 49.8 0.4 0:19.96 dd After moving one of them into a subgroup: [root@km_kirkwood /sys/fs/cgroup/cpu]# echo 623 > browser/tasks PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 623 root 20 0 1924 492 420 R 99.4 0.4 0:38.07 dd 622 root 20 0 1924 492 420 R 0.3 0.4 0:30.15 dd Regards Holger -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
