Messages in this thread | | | Date | Mon, 7 Jan 2013 11:58:18 -0600 | From | Shawn Bohrer <> | Subject | Re: kernel BUG at kernel/sched_rt.c:493! |
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On Sat, Jan 05, 2013 at 11:46:32AM -0600, Shawn Bohrer wrote: > I've tried reproducing the issue, but so far I've been unsuccessful > but I believe that is because my RT tasks aren't using enough CPU > cause borrowing from the other runqueues. Normally our RT tasks use > very little CPU so I'm not entirely sure what conditions caused them > to run into throttling on the day that this happened.
I've managed to reproduce this a couple times now on 3.1.9 I'll give this a try later with a more recent kernel. Here is what I've done to reproduce the issue.
# Setup in shell 1 root@berbox39:/cgroup/cpuset# mkdir package0 root@berbox39:/cgroup/cpuset# echo 0 > package0/cpuset.mems root@berbox39:/cgroup/cpuset# echo 0,2,4,6 > package0/cpuset.cpus root@berbox39:/cgroup/cpuset# cat cpuset.sched_load_balance 1 root@berbox39:/cgroup/cpuset# cat package0/cpuset.sched_load_balance 1 root@berbox39:/cgroup/cpuset# cat sysdefault/cpuset.sched_load_balance 1 root@berbox39:/cgroup/cpuset# echo 1,3,5,7 > sysdefault/cpuset.cpus root@berbox39:/cgroup/cpuset# echo 0 > sysdefault/cpuset.mems root@berbox39:/cgroup/cpuset# echo $$ > package0/tasks
# Setup in shell 2 root@berbox39:~# cd /cgroup/cpuset/ root@berbox39:/cgroup/cpuset# chrt -f -p 60 $$ root@berbox39:/cgroup/cpuset# echo $$ > sysdefault/tasks
# In shell 1 root@berbox39:/cgroup/cpuset# chrt -f 1 /root/burn.sh & root@berbox39:/cgroup/cpuset# chrt -f 1 /root/burn.sh &
# In shell 2 root@berbox39:/cgroup/cpuset# echo 0 > cpuset.sched_load_balance root@berbox39:/cgroup/cpuset# echo 1 > cpuset.sched_load_balance root@berbox39:/cgroup/cpuset# echo 0 > cpuset.sched_load_balance root@berbox39:/cgroup/cpuset# echo 1 > cpuset.sched_load_balance
I haven't found the exact magic combination but I've been going back and forth adding/killing burn.sh processes and toggling cpuset.sched_load_balance and in a couple of minutes I can usually get the machine to trigger the bug.
-- Shawn
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