Commit-ID: 620316e52a923811fe9a77ceb43eebf5f507d375
Gitweb: http://git.kernel.org/tip/620316e52a923811fe9a77ceb43eebf5f507d375
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Sat, 30 Jan 2016 21:32:09 -0800
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 31 Mar 2016 13:39:47 -0700
rcutorture: Avoid RCU CPU stall warning and RT throttling
Running rcuperf can result in RCU CPU stall warnings and RT throttling.
These occur because on of the real-time writer processes does
ftrace_dump() while still running at real-time priority. This commit
therefore prevents these problems by setting the writer thread back to
SCHED_NORMAL (AKA SCHED_OTHER) before doing ftrace_dump().
In addition, this commit adds a small fixed delay before dumping ftrace
buffer in order to decrease the probability that this dumping will
interfere with other writers' grace periods.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/rcuperf.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index 2786001..4c05728 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -404,11 +404,15 @@ rcu_perf_writer(void *arg)
started = true;
if (!done && i >= MIN_MEAS) {
done = true;
+ sp.sched_priority = 0;
+ sched_setscheduler_nocheck(current,
+ SCHED_NORMAL, &sp);
pr_alert("%s" PERF_FLAG
"rcu_perf_writer %ld has %d measurements\n",
perf_type, me, MIN_MEAS);
if (atomic_inc_return(&n_rcu_perf_writer_finished) >=
nrealwriters) {
+ schedule_timeout_interruptible(10);
rcu_ftrace_dump(DUMP_ALL);
PERFOUT_STRING("Test complete");
t_rcu_perf_writer_finished = t;
--
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