rcuscale: Print grace-period kthread CPU time, if recorded

This commit prints out the CPU time consumed by the grace-period kthread,
if the specified RCU flavor supports this notion.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuscale.sh

@@ -40,6 +40,10 @@ awk '
 	sum += $5 / 1000.;
 }
 
+/rcu_scale: Grace-period kthread CPU time/ {
+	cputime = $6;
+}
+
 END {
 	newNR = asort(gptimes);
 	if (newNR <= 0) {
@@ -78,6 +82,8 @@ END {
 	print "90th percentile grace-period duration: " gptimes[pct90];
 	print "99th percentile grace-period duration: " gptimes[pct99];
 	print "Maximum grace-period duration: " gptimes[newNR];
-	print "Grace periods: " ngps + 0 " Batches: " nbatches + 0 " Ratio: " ngps / nbatches;
+	if (cputime != "")
+		cpustr = " CPU: " cputime;
+	print "Grace periods: " ngps + 0 " Batches: " nbatches + 0 " Ratio: " ngps / nbatches cpustr;
 	print "Computed from rcuscale printk output.";
 }'