From: Paul E. McKenney Date: Sun, 31 Jan 2016 05:32:09 +0000 (-0800) Subject: rcutorture: Avoid RCU CPU stall warning and RT throttling X-Git-Tag: v4.7-rc1~196^2^2^4~12 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=620316e52a923811fe9a77ceb43eebf5f507d375;p=linux.git 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 --- diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c index 278600143bb6..4c0572859ff0 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;