#!/bin/bash

# Full dyntick CPU on which we'll run the user loop,
# it must be part of nohz_full kernel parameter
TARGET=1

NR_CPUS=$(getconf  _NPROCESSORS_ONLN)

# Migrate nocb tasks to CPU 0
# Beware, this assume that there is no online CPU > NR_CPUS
for CPU in $(seq $(($NR_CPUS-1)))
do
	PIDS=$(ps -o pid= -C rcuob/$CPU,rcuos/$CPU,rcuop/$CPU)
	for PID in $PIDS
	do
		taskset -cp 0 $PID
	done

done

# Migrate irqs to CPU 0
for D in $(ls /proc/irq)
do
	if [[ -x "/proc/irq/$D" && $D != "0" ]]
	then
		echo $D
		echo 1 > /proc/irq/$D/smp_affinity
	fi
done

# Delay the annoying vmstat timer far away
sysctl vm.stat_interval=120

# Shutdown nmi watchdog as it uses perf events
sysctl -w kernel.watchdog=0

DIR=/sys/kernel/debug/tracing
echo > $DIR/trace
echo 0 > $DIR/tracing_on
# Uncomment the below for more details on what disturbs the CPU
#echo 0 > $DIR/events/irq/enable
#echo 1 > $DIR/events/sched/sched_switch/enable
#echo 1 > $DIR/events/workqueue/workqueue_queue_work/enable
echo 1 > $DIR/events/workqueue/workqueue_execute_start/enable
echo 1 > $DIR/events/timer/hrtimer_expire_entry/enable
echo 1 > $DIR/events/timer/tick_stop/enable
echo nop > $DIR/current_tracer
echo 1 > $DIR/tracing_on

# Run a 10 secs user loop on target
taskset -c $TARGET ./user_loop &
sleep 10
killall user_loop

# Checkout the trace in trace.* file
cat /sys/kernel/debug/tracing/per_cpu/cpu$TARGET/trace > trace.$TARGET