tuna: Don't touch the migration/* thread scheduler policy/prio

As:

[root@sandy tuna]# chrt --pid 8
pid 8's current scheduling policy: SCHED_FIFO
pid 8's current scheduling priority: 99
[root@sandy tuna]#
[root@sandy tuna]# tuna -t 8 -P
                      thread       ctxt_switches
    pid SCHED_ rtpri affinity voluntary nonvoluntary      cmd
  8       FIFO    99        0     59190            0 migration/0
[root@sandy tuna]#
[root@sandy tuna]# chrt --fifo --pid 99 8
chrt: failed to set pid 8's policy: Invalid argument
[root@sandy tuna]# chrt --fifo --pid 98 8
chrt: failed to set pid 8's policy: Invalid argument

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/tuna/tuna.py b/tuna/tuna.py
index a7a24a7..290ff35 100755
--- a/tuna/tuna.py
+++ b/tuna/tuna.py
@@ -478,8 +478,13 @@ def get_kthread_sched_tunings(proc = None):
 
 	kthreads = {}
 	for pid in proc.keys():
-		if iskthread(pid):
-			name = proc[pid]["stat"]["comm"]
+		name = proc[pid]["stat"]["comm"]
+		# Trying to set the priority of the migration threads will
+		# fail, at least on 3.6.0-rc1 and doesn't make sense anyway
+		# and this function is only used to save those priorities
+		# to reset them using tools like rtctl, skip those to
+		# avoid sched_setscheduler/chrt to fail
+		if iskthread(pid) and not name.startswith("migration/"):
 			rtprio = int(proc[pid]["stat"]["rt_priority"])
 			try:
 				policy = schedutils.get_scheduler(pid)