@@ -17,6 +17,7 @@ SUB_DIRS = alignment \
benchmarks \
cache_shape \
copyloops \
+ cpuidle_latency \
dexcr \
dscr \
mm \
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@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+cpuidle_latency.log
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@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+all:
+
+TEST_PROGS := cpuidle_latency.sh
+
+include ../../lib.mk
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@@ -0,0 +1,443 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# CPU-Idle latency selftest enables systematic retrieval and presentation
+# of IPI and timer-triggered wake-up latencies for every CPU and available
+# system idle state by leveraging the test_cpuidle_latency module.
+#
+# Author: Pratik R. Sampat <psampat at linux.ibm.com>
+# Author: Aboorva Devarajan <aboorvad at linux.ibm.com>
+
+DISABLE=1
+ENABLE=0
+
+LOG=cpuidle_latency.log
+MODULE=/lib/modules/$(uname -r)/kernel/arch/powerpc/kernel/test_cpuidle_latency.ko
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+exit_status=0
+
+RUN_TIMER_TEST=1
+TIMEOUT=1000000
+VERBOSE=0
+
+IPI_SRC_CPU=0
+
+helpme() {
+ printf "Usage: %s [-h] [-todg args]
+ [-h <help>]
+ [-s <source cpu for ipi test> (default: 0)]
+ [-m <location of the module>]
+ [-o <location of the output>]
+ [-v <verbose> (execute test across all CPU threads)]
+ [-i <run timer tests>]
+ \n" "$0"
+ exit 2
+}
+
+cpu_is_online() {
+ local cpu=$1
+ if [ ! -f "/sys/devices/system/cpu/cpu$cpu/online" ]; then
+ printf "CPU %s: file not found: /sys/devices/system/cpu/cpu%s/online" "$cpu" "$cpu"
+ return 0
+ fi
+ status=$(cat /sys/devices/system/cpu/cpu"$cpu"/online)
+ return "$status"
+}
+
+check_valid_cpu() {
+ local cpu="$1"
+ local cpu_count
+
+ cpu_count="$(nproc)" # Get the number of CPUs on the system
+
+ if [[ "$cpu" =~ ^[0-9]+$ ]]; then
+ if ((cpu >= 0 && cpu < cpu_count)); then
+ cpu_is_online "$cpu"
+ online_status=$?
+ if [ "$online_status" -eq "1" ]; then
+ return 1
+ else
+ printf "CPU %s is offline." "$cpu"
+ return 0
+ fi
+ fi
+ fi
+ return 0
+}
+
+parse_arguments() {
+ while getopts ht:m:s:o:vt:it: arg; do
+ case $arg in
+ h) # --help
+ helpme
+ ;;
+ m) # --mod-file
+ MODULE=$OPTARG
+ ;;
+ s) #
+ IPI_SRC_CPU=$OPTARG
+ check_valid_cpu "$IPI_SRC_CPU"
+ cpu_status=$?
+ if [ "$cpu_status" == "0" ]; then
+ printf "%s is an invalid CPU. Exiting.." "$IPI_SRC_CPU"
+ exit
+ fi
+ ;;
+ o) # output log files
+ LOG=$OPTARG
+ ;;
+ v) # verbose mode - execute tests across all CPU threads
+ VERBOSE=1
+ ;;
+ i) # run timer tests
+ RUN_TIMER_TEST=1
+ ;;
+ \?)
+ helpme
+ ;;
+ esac
+ done
+}
+
+ins_mod() {
+ debugfs_file=/sys/kernel/debug/powerpc/latency_test/ipi_latency_ns
+ # Check if the module is already loaded
+ if [ -f "$debugfs_file" ]; then
+ printf "Module %s already loaded\n\n" "$MODULE"
+ return 0
+ fi
+ # Try to load the module
+ if [ ! -f "$MODULE" ]; then
+ printf "%s module does not exist. Exiting\n" "$MODULE"
+ exit $ksft_skip
+ fi
+ printf "Inserting %s module\n\n" "$MODULE"
+ insmod "$MODULE"
+ if [ $? != 0 ]; then
+ printf "Insmod %s failed\n" "$MODULE"
+ exit $ksft_skip
+ fi
+}
+
+compute_average() {
+ arr=("$@")
+ sum=0
+ size=${#arr[@]}
+ if [ "$size" == 0 ]; then
+ avg=0
+ return 1
+ fi
+ for i in "${arr[@]}"; do
+ sum=$((sum + i))
+ done
+ avg=$((sum / size))
+}
+
+# Perform operation on each CPU for the given state
+# $1 - Operation: enable (0) / disable (1)
+# $2 - State to enable
+op_state() {
+ for ((cpu = 0; cpu < NUM_CPUS; cpu++)); do
+ cpu_is_online "$cpu"
+ local cpu_status=$?
+ if [ "$cpu_status" == 0 ]; then
+ continue
+ fi
+ echo "$1" >/sys/devices/system/cpu/cpu"$cpu"/cpuidle/state"$2"/disable
+ done
+}
+
+cpuidle_enable_state() {
+ state=$1
+ op_state "$ENABLE" "$state"
+}
+
+cpuidle_disable_state() {
+ state=$1
+ op_state "$DISABLE" "$state"
+}
+
+# Enable/Disable all stop states for all CPUs
+# $1 - Operation: enable (0) / disable (1)
+op_cpuidle() {
+ for ((state = 0; state < NUM_STATES; state++)); do
+ op_state "$1" "$state"
+ done
+}
+
+extract_state_information() {
+ for ((state = 0; state < NUM_STATES; state++)); do
+ state_name=$(cat /sys/devices/system/cpu/cpu"$IPI_SRC_CPU"/cpuidle/state"$state"/name)
+ state_name_arr+=("$state_name")
+ done
+}
+
+# Extract latency in microseconds and convert to nanoseconds
+extract_latency() {
+ for ((state = 0; state < NUM_STATES; state++)); do
+ latency=$(($(cat /sys/devices/system/cpu/cpu"$IPI_SRC_CPU"/cpuidle/state"$state"/latency) * 1000))
+ latency_arr+=("$latency")
+ done
+}
+
+# Simple linear search in an array
+# $1 - Element to search for
+# $2 - Array
+element_in() {
+ local item="$1"
+ shift
+ for element in "$@"; do
+ if [ "$element" == "$item" ]; then
+ return 0
+ fi
+ done
+ return 1
+}
+
+# Parse and return a cpuset with ","(individual) and "-" (range) of CPUs
+# $1 - cpuset string
+parse_cpuset() {
+ echo "$1" | awk '/-/{for (i=$1; i<=$2; i++)printf "%s%s",i,ORS;next} {print}' RS=, FS=-
+}
+
+extract_core_information() {
+ declare -a thread_arr
+ for ((cpu = 0; cpu < NUM_CPUS; cpu++)); do
+ cpu_is_online "$cpu"
+ local cpu_status=$?
+ if [ "$cpu_status" == 0 ]; then
+ continue
+ fi
+
+ siblings=$(cat /sys/devices/system/cpu/cpu"$cpu"/topology/thread_siblings_list)
+ sib_arr=()
+
+ for c in $(parse_cpuset "$siblings"); do
+ sib_arr+=("$c")
+ done
+
+ if [ "$VERBOSE" == 1 ]; then
+ core_arr+=("$cpu")
+ continue
+ fi
+ element_in "${sib_arr[0]}" "${thread_arr[@]}"
+ if [ $? == 0 ]; then
+ continue
+ fi
+ core_arr+=("${sib_arr[0]}")
+
+ for thread in "${sib_arr[@]}"; do
+ thread_arr+=("$thread")
+ done
+ done
+
+ src_siblings=$(cat /sys/devices/system/cpu/cpu"$IPI_SRC_CPU"/topology/thread_siblings_list)
+ for c in $(parse_cpuset "$src_siblings"); do
+ first_core_arr+=("$c")
+ done
+}
+
+# Run the IPI test
+# $1 run for baseline - busy cpu or regular environment
+# $2 destination cpu
+ipi_test_once() {
+ dest_cpu=$2
+ if [ "$1" = "baseline" ]; then
+ # Keep the CPU busy
+ taskset -c "$dest_cpu" cat /dev/random >/dev/null &
+ task_pid=$!
+ # Wait for the workload to achieve 100% CPU usage
+ sleep 1
+ fi
+ taskset -c "$IPI_SRC_CPU" echo "$dest_cpu" >/sys/kernel/debug/powerpc/latency_test/ipi_cpu_dest
+ ipi_latency=$(cat /sys/kernel/debug/powerpc/latency_test/ipi_latency_ns)
+ src_cpu=$(cat /sys/kernel/debug/powerpc/latency_test/ipi_cpu_src)
+ if [ "$1" = "baseline" ]; then
+ kill "$task_pid"
+ wait "$task_pid" 2>/dev/null
+ fi
+}
+
+# Incrementally enable idle states one by one and compute the latency
+run_ipi_tests() {
+ extract_latency
+ # Disable idle states for CPUs
+ op_cpuidle "$DISABLE"
+
+ declare -a avg_arr
+ printf "...IPI Latency Test...\n" | tee -a "$LOG"
+
+ printf "...Baseline IPI Latency measurement: CPU Busy...\n" >>"$LOG"
+ printf "%s %10s %12s\n" "SRC_CPU" "DEST_CPU" "IPI_Latency(ns)" >>"$LOG"
+ for cpu in "${core_arr[@]}"; do
+ cpu_is_online "$cpu"
+ local cpu_status=$?
+ if [ "$cpu_status" == 0 ]; then
+ continue
+ fi
+ ipi_test_once "baseline" "$cpu"
+ printf "%-3s %10s %12s\n" "$src_cpu" "$cpu" "$ipi_latency" >>"$LOG"
+ # Skip computing latency average from the source CPU to avoid bias
+ element_in "$cpu" "${first_core_arr[@]}"
+ if [ $? == 0 ]; then
+ continue
+ fi
+ avg_arr+=("$ipi_latency")
+ done
+ compute_average "${avg_arr[@]}"
+ printf "Baseline Avg IPI latency(ns): %s\n" "$avg" | tee -a "$LOG"
+
+ for ((state = 0; state < NUM_STATES; state++)); do
+ unset avg_arr
+ printf "...Enabling state: %s...\n" "${state_name_arr[$state]}" >>"$LOG"
+ cpuidle_enable_state $state
+ printf "%s %10s %12s\n" "SRC_CPU" "DEST_CPU" "IPI_Latency(ns)" >>"$LOG"
+ for cpu in "${core_arr[@]}"; do
+ cpu_is_online "$cpu"
+ local cpu_status=$?
+ if [ "$cpu_status" == 0 ]; then
+ continue
+ fi
+ # Running IPI test and logging results
+ sleep 1
+ ipi_test_once "test" "$cpu"
+ printf "%-3s %10s %12s\n" "$src_cpu" "$cpu" "$ipi_latency" >>"$LOG"
+ # Skip computing latency average from the source CPU to avoid bias
+ element_in "$cpu" "${first_core_arr[@]}"
+ if [ $? == 0 ]; then
+ continue
+ fi
+ avg_arr+=("$ipi_latency")
+ done
+
+ compute_average "${avg_arr[@]}"
+ printf "Expected IPI latency(ns): %s\n" "${latency_arr[$state]}" >>"$LOG"
+ printf "Observed Avg IPI latency(ns) - State %s: %s\n" "${state_name_arr[$state]}" "$avg" | tee -a "$LOG"
+ cpuidle_disable_state $state
+ done
+}
+
+# Extract the residency in microseconds and convert to nanoseconds.
+# Add 200 ns so that the timer stays for a little longer than the residency
+extract_residency() {
+ for ((state = 0; state < NUM_STATES; state++)); do
+ residency=$(($(cat /sys/devices/system/cpu/cpu"$IPI_SRC_CPU"/cpuidle/state"$state"/residency) * 1000 + 200))
+ residency_arr+=("$residency")
+ done
+}
+
+# Run the Timeout test
+# $1 run for baseline - busy cpu or regular environment
+# $2 destination cpu
+# $3 timeout
+timeout_test_once() {
+ dest_cpu=$2
+ if [ "$1" = "baseline" ]; then
+ # Keep the CPU busy
+ taskset -c "$dest_cpu" cat /dev/random >/dev/null &
+ task_pid=$!
+ # Wait for the workload to achieve 100% CPU usage
+ sleep 1
+ fi
+ taskset -c "$dest_cpu" sleep 1
+ taskset -c "$dest_cpu" echo "$3" >/sys/kernel/debug/powerpc/latency_test/timeout_expected_ns
+ # Wait for the result to populate
+ sleep 0.1
+ timeout_diff=$(cat /sys/kernel/debug/powerpc/latency_test/timeout_diff_ns)
+ src_cpu=$(cat /sys/kernel/debug/powerpc/latency_test/timeout_cpu_src)
+ if [ "$1" = "baseline" ]; then
+ kill "$task_pid"
+ wait "$task_pid" 2>/dev/null
+ fi
+}
+
+run_timeout_tests() {
+ extract_residency
+ # Disable idle states for all CPUs
+ op_cpuidle "$DISABLE"
+
+ declare -a avg_arr
+ printf "\n...Timeout Latency Test...\n" | tee -a "$LOG"
+
+ printf "...Baseline Timeout Latency measurement: CPU Busy...\n" >>"$LOG"
+ printf "%s %10s\n" "Wakeup_src" "Baseline_delay(ns)" >>"$LOG"
+ for cpu in "${core_arr[@]}"; do
+ cpu_is_online "$cpu"
+ local cpu_status=$?
+ if [ "$cpu_status" == 0 ]; then
+ continue
+ fi
+ timeout_test_once "baseline" "$cpu" "$TIMEOUT"
+ printf "%-3s %13s\n" "$src_cpu" "$timeout_diff" >>"$LOG"
+ avg_arr+=("$timeout_diff")
+ done
+ compute_average "${avg_arr[@]}"
+ printf "Baseline Avg timeout diff(ns): %s\n" "$avg" | tee -a "$LOG"
+
+ for ((state = 0; state < NUM_STATES; state++)); do
+ unset avg_arr
+ printf "...Enabling state: %s...\n" "${state_name_arr["$state"]}" >>"$LOG"
+ cpuidle_enable_state "$state"
+ printf "%s %10s\n" "Wakeup_src" "Delay(ns)" >>"$LOG"
+ for cpu in "${core_arr[@]}"; do
+ cpu_is_online "$cpu"
+ local cpu_status=$?
+ if [ "$cpu_status" == 0 ]; then
+ continue
+ fi
+ timeout_test_once "test" "$cpu" "$TIMEOUT"
+ printf "%-3s %13s\n" "$src_cpu" "$timeout_diff" >>"$LOG"
+ avg_arr+=("$timeout_diff")
+ done
+ compute_average "${avg_arr[@]}"
+ printf "Expected timeout(ns): %s\n" "${residency_arr["$state"]}" >>"$LOG"
+ printf "Observed Avg timeout diff(ns) - State %s: %s\n" "${state_name_arr["$state"]}" "$avg" | tee -a "$LOG"
+ cpuidle_disable_state "$state"
+ done
+}
+
+# Function to exit the test if not intended
+exit_test() {
+ printf "Exiting the test. Test not intended to run.\n"
+ exit "$ksft_skip"
+}
+
+printf "Running this test enables all CPU idle states by the time it concludes.\n"
+printf "Note: This test does not restore previous idle state.\n"
+
+declare -a residency_arr
+declare -a latency_arr
+declare -a core_arr
+declare -a first_core_arr
+declare -a state_name_arr
+
+parse_arguments "$@"
+
+rm -f "$LOG"
+touch "$LOG"
+
+NUM_CPUS=$(nproc --all)
+NUM_STATES=$(ls -1 /sys/devices/system/cpu/cpu"$IPI_SRC_CPU"/cpuidle/ | wc -l)
+
+extract_core_information
+extract_state_information
+
+ins_mod "$MODULE"
+
+run_ipi_tests
+if [ "$RUN_TIMER_TEST" == "1" ]; then
+ run_timeout_tests
+fi
+
+# Enable all idle states for all CPUs
+op_cpuidle $ENABLE
+printf "Removing %s module\n" "$MODULE"
+printf "Full Output logged at: %s\n" "$LOG"
+
+if [ -f "$MODULE" ]; then
+ rmmod "$MODULE"
+fi
+
+exit "$exit_status"
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@@ -0,0 +1 @@
+timeout=0