Add governor.sh to run benchmarks from a performance state on Linux

The script is based on code by Andy Polyakov, http://www.openssl.org/~appro/cryptogams.

TestScripts/governor.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+# This scripts queries and modifies CPU scaling frequencies to produce more
+# accurate benchmark results. To move from a low energy state C-state to a
+# higher one, run 'governor.sh performance'. To move back to a low power state
+# run 'governor.sh powersave' or reboot. The script is based on code by
+# Andy Polyakov, http://www.openssl.org/~appro/cryptogams/.
+
+if [ "x$1" = "x" ]; then
+    echo "usage: $0 on[demand]|pe[rformance]|?"
+    [[ "$0" = "$BASH_SOURCE" ]] && exit 1 || return 1
+fi
+
+# "on demand" may result in a "invalid write argument" or similar
+case $1 in
+    on*|de*)    governor="ondemand";;
+    po*|pw*)    governor="powersave";;
+    pe*)        governor="performance";;
+    us*)        governor="userspace";;
+    \?)         ;;
+    *)          echo "$1: unrecognized governor";;
+esac
+
+if [ -z "$governor" ]; then
+	[[ "$0" = "$BASH_SOURCE" ]] && exit 1 || return 1
+fi
+
+cpus=$(ls /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor 2>/dev/null)
+
+if [ -z "$cpus" ]; then
+	echo "Failed to read CPU system device tree"
+	[[ "$0" = "$BASH_SOURCE" ]] && exit 1 || return 1
+fi
+
+echo "Current CPU governor scaling settings:"
+count=0
+for cpu in $cpus; do
+	echo "  CPU $count:" $(cat "$cpu")
+	((count++))
+done
+
+if [ "x$governor" != "x" ]; then
+    for cpu in $cpus; do
+        echo $governor > $cpu
+    done
+fi
+
+echo "New CPU governor scaling settings:"
+count=0
+for cpu in $cpus; do
+	echo "  CPU $count:" $(cat "$cpu")
+	((count++))
+done
+
+[[ "$0" = "$BASH_SOURCE" ]] && exit 0 || return 0