benchmark: improve cpu.sh for safety and usability

The previous cpu.sh script was minimal. This change makes it a more robust and safe utility for managing CPU governors during benchmarks. The script now includes: - Checks to ensure it only runs on Linux with root privileges. - A `reset` command to restore the CPU governor to a dynamically detected system default. - A `get` command to check the current governor for all cores. - An improved usage guide and clearer feedback messages. PR-URL: #60162 Reviewed-By: Antoine du Hamel <[email protected]>

Author: meteorqz6

benchmark/cpu.sh

@@ -4,21 +4,73 @@ CPUPATH=/sys/devices/system/cpu
 
 MAXID=$(cat $CPUPATH/present | awk -F- '{print $NF}')
 
+[ "$(uname -s || true)"="Linux" ] || \
+echo"Warning: This script supports Linux only.">&2
+
+[ "$(id -u || true)"="0" ] || \
+echo"Warning: This script typically needs root access to modify CPU governor. Consider running it with sudo.">&2
+
+get_default_governor(){
+case"$(cat "$CPUPATH/cpu0/cpufreq/scaling_available_governors")"in
+*"schedutil"*) echo"schedutil" ;
+*"ondemand"*) echo"ondemand" ;
+*"conservative"*) echo"conservative";
+*) echo"powersave" ;
+esac
+
+}
+
 set_governor(){
-echo"Setting CPU frequency governor to \"$1\""
+ governor_name="$1"
+
+echo"Setting governor for all CPU cores to \"$governor_name\"..."
+
  i=0
 while [ "$i"-le"$MAXID" ];do
 echo"$1">"$CPUPATH/cpu$i/cpufreq/scaling_governor"
  i=$((i +1))
 done
+
+echo"Done."
+}
+
+usage(){
+ default_gov=$(get_default_governor)
+echo"CPU Governor Management Script"
+echo"----------------------------------------------------------------------------"
+echo"Usage: $0 [command]"
+echo
+echo"Commands:"
+echo" fast Sets the governor to 'performance' for maximum speed."
+echo" (Warning: Increases heat/power use. Use for short-term tasks.)"
+echo
+echo" reset Resets the governor to the system's recommended default ('$default_gov')."
+echo
+echo" get Shows the current CPU governor for ALL cores."
+echo"----------------------------------------------------------------------------"
 }
 
 case"$1"in
  fast | performance)
+echo"Warning: The 'performance' mode locks the CPU at its highest speed."
+echo"It is highly recommended to 'reset' after your task is complete."
  set_governor "performance"
  ;
+
+ reset | default)
+ default_governor=$(get_default_governor)
+ set_governor "$default_governor"
+ ;
+
+ get | status)
+echo"Current governor status for all cores:"
+ grep ."$CPUPATH"/cpu*/cpufreq/scaling_governor
+ ;
+
 *)
-echo"Usage: $0 fast"
+usage
 exit 1
  ;
 esac
+
+exit 0