rcutorture: Make scripts analyze rcuperf trace data, if present

The rcuperf event-trace data is more accurate than are the rcuperf
printk()s because locking keeps things ordered.  This commit therefore
parses and analyzes this event-trace data if present, and falls back on
the printk()s otherwise.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh

+#!/bin/bash
+#
+# Analyze a given results directory for rcuperf performance measurements,
+# looking for ftrace data.  Exits with 0 if data was found, analyzed, and
+# printed.  Intended to be invoked from kvm-recheck-rcuperf.sh after
+# argument checking.
+#
+# Usage: kvm-recheck-rcuperf-ftrace.sh resdir
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, you can access it online at
+# http://www.gnu.org/licenses/gpl-2.0.html.
+#
+# Copyright (C) IBM Corporation, 2016
+#
+# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+i="$1"
+. tools/testing/selftests/rcutorture/bin/functions.sh
+
+if test "`grep -c 'rcu_exp_grace_period.*start' < $i/console.log`" -lt 100
+then
+	exit 10
+fi
+
+sed -e 's/^\[[^]]*]//' < $i/console.log |
+grep 'us : rcu_exp_grace_period' |
+sed -e 's/us : / : /' |
+tr -d '\015' |
+awk '
+$8 == "start" {
+	if (starttask != "")
+		nlost++;
+	starttask = $1;
+	starttime = $3;
+	startseq = $7;
+}
+
+$8 == "end" {
+	if (starttask == $1 && startseq == $7) {
+		curgpdur = $3 - starttime;
+		gptimes[++n] = curgpdur;
+		gptaskcnt[starttask]++;
+		sum += curgpdur;
+		if (curgpdur > 1000)
+			print "Long GP " starttime "us to " $3 "us (" curgpdur "us)";
+		starttask = "";
+	} else {
+		# Lost a message or some such, reset.
+		starttask = "";
+		nlost++;
+	}
+}
+
+$8 == "done" {
+	piggybackcnt[$1]++;
+}
+
+END {
+	newNR = asort(gptimes);
+	if (newNR <= 0) {
+		print "No ftrace records found???"
+		exit 10;
+	}
+	pct50 = int(newNR * 50 / 100);
+	if (pct50 < 1)
+		pct50 = 1;
+	pct90 = int(newNR * 90 / 100);
+	if (pct90 < 1)
+		pct90 = 1;
+	pct99 = int(newNR * 99 / 100);
+	if (pct99 < 1)
+		pct99 = 1;
+	div = 10 ** int(log(gptimes[pct90]) / log(10) + .5) / 100;
+	print "Histogram bucket size: " div;
+	last = gptimes[1] - 10;
+	count = 0;
+	for (i = 1; i <= newNR; i++) {
+		current = div * int(gptimes[i] / div);
+		if (last == current) {
+			count++;
+		} else {
+			if (count > 0)
+				print last, count;
+			count = 1;
+			last = current;
+		}
+	}
+	if (count > 0)
+		print last, count;
+	print "Distribution of grace periods across tasks:";
+	for (i in gptaskcnt) {
+		print "\t" i, gptaskcnt[i];
+		nbatches += gptaskcnt[i];
+	}
+	ngps = nbatches;
+	print "Distribution of piggybacking across tasks:";
+	for (i in piggybackcnt) {
+		print "\t" i, piggybackcnt[i];
+		ngps += piggybackcnt[i];
+	}
+	print "Average grace-period duration: " sum / newNR " microseconds";
+	print "Minimum grace-period duration: " gptimes[1];
+	print "50th percentile grace-period duration: " gptimes[pct50];
+	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 " Lost: " nlost + 0;
+	print "Computed from ftrace data.";
+}'
+exit 0

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

@@ -30,8 +30,15 @@ else
 	echo Unreadable results directory: $i
 	exit 1
 fi
+PATH=`pwd`/tools/testing/selftests/rcutorture/bin:$PATH; export PATH
 . tools/testing/selftests/rcutorture/bin/functions.sh
 
+if kvm-recheck-rcuperf-ftrace.sh $i
+then
+	# ftrace data was successfully analyzed, call it good!
+	exit 0
+fi
+
 configfile=`echo $i | sed -e 's/^.*\///'`
 
 sed -e 's/^\[[^]]*]//' < $i/console.log |
@@ -85,4 +92,5 @@ END {
 	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;
+	print "Computed from rcuperf printk output.";
 }'