From 0ea89560253042afcb4b11cf666a86bfb6851e12 Mon Sep 17 00:00:00 2001
From: Michal Berger <michalx.berger@intel.com>
Date: Thu, 22 Apr 2021 15:22:11 +0200
Subject: [PATCH] test/scheduler: Add function for calculating cpu load

This is done in order to detect cpu times in a more deterministic
fashion.

Signed-off-by: Michal Berger <michalx.berger@intel.com>
Change-Id: I005d6fececdc15500bcf637e96f2fbecbd4273f1
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/7563
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
---
 test/scheduler/common.sh | 96 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 93 insertions(+), 3 deletions(-)

diff --git a/test/scheduler/common.sh b/test/scheduler/common.sh
index 62ff348c7..8e5f92041 100644
--- a/test/scheduler/common.sh
+++ b/test/scheduler/common.sh
@@ -370,14 +370,15 @@ _get_thread_stats() {
 
 get_cpu_stat() {
 	local cpu_idx=$1
-	local stat=$2 stats
+	local stat=$2 stats astats
 
 	while read -r cpu stats; do
-		[[ $cpu == "cpu$cpu_idx" ]] && stats=($stats)
+		[[ $cpu == "cpu$cpu_idx" ]] && astats=($stats)
 	done < /proc/stat
 
 	case "$stat" in
-		idle) echo "${stats[3]}" ;;
+		idle) echo "${astats[3]}" ;;
+		all) printf '%u\n' "${astats[@]}" ;;
 		*) ;;
 	esac
 }
@@ -393,3 +394,92 @@ destroy_thread() {
 active_thread() {
 	rpc_cmd --plugin "$plugin" scheduler_thread_set_active "$@"
 }
+
+get_cpu_time() {
+	xtrace_disable
+
+	local interval=$1 cpu_time=$2 interval_count
+	shift 2
+	local cpus=("$@") cpu
+	local stats stat old_stats avg_load
+	local total_sample
+
+	# Exposed for the caller
+	local -g cpu_times=()
+	local -g avg_cpu_time=()
+
+	# cpu_time:
+	# 0 - user (time spent in user mode)
+	# 1 - nice (Time spent in user mode with low priority)
+	# 2 - system (Time spent in system mode)
+	# 3 - idle (Time spent in the idle task)
+	# 4 - iowait (Time waiting for I/O to complete)
+	# 5 - irq (Time servicing interrupts)
+	# 6 - softirq (Time servicing softirqs)
+	# 7 - steal (Stolen time)
+	# 8 - guest (Time spent running a virtual CPU)
+	# 9 - guest_nice (Time spent running a niced guest)
+
+	local -A cpu_time_map
+	cpu_time_map["user"]=0
+	cpu_time_map["nice"]=1
+	cpu_time_map["system"]=2
+	cpu_time_map["idle"]=3
+	cpu_time_map["iowait"]=4
+	cpu_time_map["irq"]=5
+	cpu_time_map["softirq"]=6
+	cpu_time_map["steal"]=7
+	cpu_time_map["guest"]=8
+	cpu_time_map["guest_nice"]=9
+
+	# Clear up the env
+	unset -v ${!stat_@}
+	unset -v ${!old_stat_@}
+	unset -v ${!avg_stat@}
+	unset -v ${!avg_load@}
+
+	cpu_time=${cpu_time_map["$cpu_time"]:-3}
+	interval=$((interval <= 0 ? 1 : interval))
+	# We skip first sample to have min 2 for stat comparision
+	interval=$((interval + 1)) interval_count=0
+	while ((interval_count++, --interval >= 0)); do
+		for cpu in "${cpus[@]}"; do
+			local -n old_stats=old_stats_$cpu
+			local -n avg_load=avg_load_$cpu
+			sample_stats=() total_sample=0
+
+			stats=($(get_cpu_stat "$cpu" all))
+			if ((interval_count == 1)); then
+				# Skip first sample
+				old_stats=("${stats[@]}")
+				continue
+			fi
+			for stat in "${!stats[@]}"; do
+				avg_load[stat]="stat_${stat}_${cpu}[@]"
+				sample_stats[stat]=$((stats[stat] - old_stats[stat]))
+				: $((total_sample += sample_stats[stat]))
+			done
+			for stat in "${!stats[@]}"; do
+				local -n avg_stat=stat_${stat}_${cpu}
+				avg_stat+=($((sample_stats[stat] * 100 / (total_sample == 0 ? 1 : total_sample))))
+			done
+			old_stats=("${stats[@]}")
+		done
+		sleep 1s
+	done
+
+	# We collected % for each time. Now determine the avg % for requested time.
+	local load stat_load
+	for cpu in "${cpus[@]}"; do
+		load=0
+		local -n avg_load_cpu=avg_load_$cpu
+		stat_load=("${!avg_load_cpu[cpu_time]}")
+		for stat in "${stat_load[@]}"; do
+			: $((load += stat))
+		done
+		cpu_times[cpu]=${stat_load[*]}
+		avg_cpu_time[cpu]=$((load / ${#stat_load[@]}))
+	done
+
+	xtrace_restore
+}