tests/generic/650

#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2021 Oracle, Inc.  All Rights Reserved.
#
# FS QA Test No. 650
#
# Run an all-writes fsstress run with multiple threads while exercising CPU
# hotplugging to shake out bugs in the write path.
#
. ./common/preamble
_begin_fstest auto rw stress

# Override the default cleanup function.
_cleanup()
{
	cd /
	rm -f $tmp.*
	$KILLALL_PROG -9 fsstress > /dev/null 2>&1
	wait	# for exercise_cpu_hotplug subprocess
	for i in "$sysfs_cpu_dir/"cpu*/online; do
		echo 1 > "$i" 2>/dev/null
	done
	test -n "$stress_dir" && rm -r -f "$stress_dir"
}

exercise_cpu_hotplug()
{
	while [ -e $sentinel_file ]; do
		local idx=$(( RANDOM % nr_hotplug_cpus ))
		local cpu="${hotplug_cpus[idx]}"
		local action=$(( RANDOM % 2 ))

		echo "$action" > "$sysfs_cpu_dir/cpu$cpu/online" 2>/dev/null
		sleep 0.5
	done
}

_supported_fs generic
_require_test
_require_command "$KILLALL_PROG" "killall"

sysfs_cpu_dir="/sys/devices/system/cpu"

# Figure out which CPU(s) support hotplug.
nrcpus=$(getconf _NPROCESSORS_CONF)
hotplug_cpus=()
for ((i = 0; i < nrcpus; i++ )); do
	test -e "$sysfs_cpu_dir/cpu$i/online" && hotplug_cpus+=("$i")
done
nr_hotplug_cpus="${#hotplug_cpus[@]}"
test "$nr_hotplug_cpus" -gt 0 || _notrun "CPU hotplugging not supported"

stress_dir="$TEST_DIR/$seq"
rm -r -f "$stress_dir"
mkdir -p "$stress_dir"

echo "Silence is golden."

sentinel_file=$tmp.hotplug
touch $sentinel_file
exercise_cpu_hotplug &

# Cap the number of fsstress threads at one per hotpluggable CPU if we exceed
# 1024 IO threads, per maintainer request.
nr_cpus=$((LOAD_FACTOR * nr_hotplug_cpus))
test "$nr_cpus" -gt 1024 && nr_cpus="$nr_hotplug_cpus"

nr_ops=$((25000 * TIME_FACTOR))
$FSSTRESS_PROG $FSSTRESS_AVOID -w -d $stress_dir -n $nr_ops -p $nr_cpus >> $seqres.full
rm -f $sentinel_file

# success, all done
status=0
exit