improve cpu metric

metrics/cpu.sh

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 collect () {
-  report $(ps aux | awk '{ sum+=$3 } END { printf "%.1f\n", sum }' | tail -n 1)
+  report $(ps axo %cpu | awk '{ sum+=$1 } END { printf "%.1f\n", sum }' | tail -n 1)
 }
 
 docs () {