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[PATCH tip/core/rcu 0/24] Torture-test changes for 4.7

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  [PATCH tip/core/rcu 0/24] Torture-test changes for 4.7 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:50 +0200
    [PATCH tip/core/rcu 11/24] rcutorture: Add rcuperf holdoff boot parameter to reduce interference "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:50 +0200
    [PATCH tip/core/rcu 17/24] torture: Clarify refusal to run more than one torture test "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 17:50 +0200
    [PATCH tip/core/rcu 01/24] rcutorture: Update scripting to accommodate rcuperf "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 18:00 +0200
    [PATCH tip/core/rcu 03/24] rcutorture: Expedited-GP batch progress access to torturing "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 18:00 +0200
    [PATCH tip/core/rcu 04/24] rcutorture: Add RCU grace-period performance tests "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 18:00 +0200
    [PATCH tip/core/rcu 05/24] rcutorture: Documentation for rcuperf kernel parameters "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-04-12 18:00 +0200

#1376968 — [PATCH tip/core/rcu 0/24] Torture-test changes for 4.7

Hello!

This series contains torture-test changes for RCU, most notably a new
test for performance of RCU grace periods named "rcuperf":

1.	Update scripting to accommodate rcuperf.

2.	Allow for rcupdate.rcu_normal in rcu_torture_writer() decisions.

3.	Expedited-GP batch progress access to torturing for progress
	statistics.

4.	Add RCU grace-period performance tests, AKA "rcuperf".

5.	Documentation for rcuperf kernel parameters.

6.	Bind rcuperf reader/writer kthreads to CPUs.

7.	Set rcuperf writer kthreads to real-time priority.

8.	Print measure of batching efficiency.

9.	Make rcuperf collect expedited event-trace data.

10.	Make scripts analyze rcuperf trace data, if present.

11.	Add rcuperf holdoff boot parameter to reduce interference.

12.	Avoid RCU CPU stall warning and RT throttling.

13.	Add largish-system rcuperf scenario.

14.	Do not wake up shutdown wait queue if "shutdown" is false, courtesy
	of Artem Savkov.

15.	Remove redundant initialization to zero.

16.	Consider FROZEN hotplug notifier transitions, courtesy of
	Anna-Maria Gleixner.

17.	Clarify refusal to run more than one torture test.

18.	Kill qemu, not parent process.

19.	Convert test duration to seconds early.

20.	Add OS-jitter capability.

21.	Don't rebuild identical kernel.

22.	Dump trace buffer upon shutdown.

23.	Add irqs-disabled test for call_rcu().

24.	Add boot-time adjustment of leaf fanout.

								Thanx, Paul

------------------------------------------------------------------------

 Documentation/kernel-parameters.txt                                  |   38 
 include/linux/rcutiny.h                                              |   16 
 include/linux/rcutree.h                                              |    2 
 kernel/rcu/Makefile                                                  |    1 
 kernel/rcu/rcuperf.c                                                 |  661 +++++++++-
 kernel/rcu/rcutorture.c                                              |   12 
 kernel/rcu/tree.c                                                    |   22 
 kernel/torture.c                                                     |    4 
 lib/Kconfig.debug                                                    |   33 
 tools/testing/selftests/rcutorture/bin/jitter.sh                     |   83 +
 tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh |  121 +
 tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf.sh        |  116 +
 tools/testing/selftests/rcutorture/bin/kvm-recheck.sh                |    5 
 tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh             |   61 
 tools/testing/selftests/rcutorture/bin/kvm.sh                        |   24 
 tools/testing/selftests/rcutorture/configs/rcu/TREE04                |    2 
 tools/testing/selftests/rcutorture/configs/rcu/TREE04.boot           |    2 
 tools/testing/selftests/rcutorture/configs/rcuperf/CFLIST            |    1 
 tools/testing/selftests/rcutorture/configs/rcuperf/CFcommon          |    2 
 tools/testing/selftests/rcutorture/configs/rcuperf/TREE              |   20 
 tools/testing/selftests/rcutorture/configs/rcuperf/TREE54            |   23 
 tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh  |   52 
 22 files changed, 1260 insertions(+), 41 deletions(-)

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#1376970 — [PATCH tip/core/rcu 11/24] rcutorture: Add rcuperf holdoff boot parameter to reduce interference

Boot-time activity can legitimately grab CPUs for extended time periods,
so the commit adds a boot parameter to delay the start of the performance
test until boot has completed.  Defaults to 10 seconds.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 Documentation/kernel-parameters.txt | 6 ++++++
 kernel/rcu/rcuperf.c                | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 951af481da5a..da9ee466789b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3288,6 +3288,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Measure performance of expedited synchronous
 			grace-period primitives.
 
+	rcuperf.holdoff= [KNL]
+			Set test-start holdoff period.  The purpose of
+			this parameter is to delay the start of the
+			test until boot completes in order to avoid
+			interference.
+
 	rcuperf.nreaders= [KNL]
 			Set number of RCU readers.  The value -1 selects
 			N, where N is the number of CPUs.  A value
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index 12561f96f0a2..278600143bb6 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -59,6 +59,7 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
 	do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0)
 
 torture_param(bool, gp_exp, true, "Use expedited GP wait primitives");
+torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
 torture_param(int, nreaders, -1, "Number of RCU reader threads");
 torture_param(int, nwriters, -1, "Number of RCU updater threads");
 torture_param(bool, shutdown, false, "Shutdown at end of performance tests.");
@@ -368,6 +369,10 @@ rcu_perf_writer(void *arg)
 	set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
 	sp.sched_priority = 1;
 	sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
+
+	if (holdoff)
+		schedule_timeout_uninterruptible(holdoff * HZ);
+
 	t = ktime_get_mono_fast_ns();
 	if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) {
 		t_rcu_perf_writer_started = t;
-- 
2.5.2

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#1376971 — [PATCH tip/core/rcu 17/24] torture: Clarify refusal to run more than one torture test

This commit clarifies error messages -- you only get to run one torture
test at a time!

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/torture.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/torture.c b/kernel/torture.c
index 44aa462d033f..e912ccd960f0 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -602,8 +602,9 @@ bool torture_init_begin(char *ttype, bool v, int *runnable)
 {
 	mutex_lock(&fullstop_mutex);
 	if (torture_type != NULL) {
-		pr_alert("torture_init_begin: refusing %s init: %s running",
+		pr_alert("torture_init_begin: Refusing %s init: %s running.\n",
 			 ttype, torture_type);
+		pr_alert("torture_init_begin: One torture test at a time!\n");
 		mutex_unlock(&fullstop_mutex);
 		return false;
 	}
-- 
2.5.2

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#1376975 — [PATCH tip/core/rcu 01/24] rcutorture: Update scripting to accommodate rcuperf

This commit adds the scripting changes to add support for the shiny
new rcuperf kernel module.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 .../rcutorture/bin/kvm-recheck-rcuperf.sh          | 82 ++++++++++++++++++++++
 .../selftests/rcutorture/bin/kvm-recheck.sh        |  5 +-
 tools/testing/selftests/rcutorture/bin/kvm.sh      |  2 +-
 .../selftests/rcutorture/configs/rcuperf/CFLIST    |  1 +
 .../selftests/rcutorture/configs/rcuperf/CFcommon  |  2 +
 .../selftests/rcutorture/configs/rcuperf/TREE      | 19 +++++
 .../rcutorture/configs/rcuperf/ver_functions.sh    | 52 ++++++++++++++
 7 files changed, 161 insertions(+), 2 deletions(-)
 create mode 100755 tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf.sh
 create mode 100644 tools/testing/selftests/rcutorture/configs/rcuperf/CFLIST
 create mode 100644 tools/testing/selftests/rcutorture/configs/rcuperf/CFcommon
 create mode 100644 tools/testing/selftests/rcutorture/configs/rcuperf/TREE
 create mode 100644 tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh

diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf.sh
new file mode 100755
index 000000000000..e5b28174fda0
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf.sh
@@ -0,0 +1,82 @@
+#!/bin/bash
+#
+# Analyze a given results directory for rcuperf performance measurements.
+#
+# Usage: kvm-recheck-rcuperf.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"
+if test -d $i
+then
+	:
+else
+	echo Unreadable results directory: $i
+	exit 1
+fi
+. tools/testing/selftests/rcutorture/bin/functions.sh
+
+configfile=`echo $i | sed -e 's/^.*\///'`
+
+grep -e '-perf:.*writer-duration' $i/console.log | sed -e 's/^\[[^]]*]//' |
+awk '
+{
+	gptimes[++n] = $5 / 1000.;
+	sum += $5 / 1000.;
+}
+
+END {
+	if (NR <= 0) {
+		print "No rcuperf records found???"
+		exit;
+	}
+	asort(gptimes);
+	pct50 = int(NR * 50 / 100);
+	if (pct50 < 1)
+		pct50 = 1;
+	pct90 = int(NR * 90 / 100);
+	if (pct90 < 1)
+		pct90 = 1;
+	pct99 = int(NR * 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 <= NR; 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 "Average grace-period duration: " sum / NR " 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[NR];
+}'
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
index d86bdd6b6cc2..f659346d3358 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
@@ -48,7 +48,10 @@ do
 				cat $i/Make.oldconfig.err
 			fi
 			parse-build.sh $i/Make.out $configfile
-			parse-torture.sh $i/console.log $configfile
+			if test "$TORTURE_SUITE" != rcuperf
+			then
+				parse-torture.sh $i/console.log $configfile
+			fi
 			parse-console.sh $i/console.log $configfile
 			if test -r $i/Warnings
 			then
diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh
index 4a431767f77a..c33cb582b3dc 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm.sh
@@ -156,7 +156,7 @@ do
 		shift
 		;;
 	--torture)
-		checkarg --torture "(suite name)" "$#" "$2" '^\(lock\|rcu\)$' '^--'
+		checkarg --torture "(suite name)" "$#" "$2" '^\(lock\|rcu\|rcuperf\)$' '^--'
 		TORTURE_SUITE=$2
 		shift
 		;;
diff --git a/tools/testing/selftests/rcutorture/configs/rcuperf/CFLIST b/tools/testing/selftests/rcutorture/configs/rcuperf/CFLIST
new file mode 100644
index 000000000000..c9f56cf20775
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcuperf/CFLIST
@@ -0,0 +1 @@
+TREE
diff --git a/tools/testing/selftests/rcutorture/configs/rcuperf/CFcommon b/tools/testing/selftests/rcutorture/configs/rcuperf/CFcommon
new file mode 100644
index 000000000000..a09816b8c0f3
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcuperf/CFcommon
@@ -0,0 +1,2 @@
+CONFIG_RCU_PERF_TEST=y
+CONFIG_PRINTK_TIME=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcuperf/TREE b/tools/testing/selftests/rcutorture/configs/rcuperf/TREE
new file mode 100644
index 000000000000..614e107f6db5
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcuperf/TREE
@@ -0,0 +1,19 @@
+CONFIG_SMP=y
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+#CHECK#CONFIG_PREEMPT_RCU=y
+CONFIG_HZ_PERIODIC=n
+CONFIG_NO_HZ_IDLE=y
+CONFIG_NO_HZ_FULL=n
+CONFIG_RCU_FAST_NO_HZ=n
+CONFIG_RCU_TRACE=n
+CONFIG_HOTPLUG_CPU=n
+CONFIG_SUSPEND=n
+CONFIG_HIBERNATION=n
+CONFIG_RCU_NOCB_CPU=n
+CONFIG_DEBUG_LOCK_ALLOC=n
+CONFIG_PROVE_LOCKING=n
+CONFIG_RCU_BOOST=n
+CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
+CONFIG_RCU_EXPERT=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh b/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh
new file mode 100644
index 000000000000..34f2a1b35ee5
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcuperf/ver_functions.sh
@@ -0,0 +1,52 @@
+#!/bin/bash
+#
+# Torture-suite-dependent shell functions for the rest of the scripts.
+#
+# 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, 2015
+#
+# Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+# rcuperf_param_nreaders bootparam-string
+#
+# Adds nreaders rcuperf module parameter if not already specified.
+rcuperf_param_nreaders () {
+	if ! echo "$1" | grep -q "rcuperf.nreaders"
+	then
+		echo rcuperf.nreaders=-1
+	fi
+}
+
+# rcuperf_param_nwriters bootparam-string
+#
+# Adds nwriters rcuperf module parameter if not already specified.
+rcuperf_param_nwriters () {
+	if ! echo "$1" | grep -q "rcuperf.nwriters"
+	then
+		echo rcuperf.nwriters=-1
+	fi
+}
+
+# per_version_boot_params bootparam-string config-file seconds
+#
+# Adds per-version torture-module parameters to kernels supporting them.
+per_version_boot_params () {
+	echo $1 `rcuperf_param_nreaders "$1"` \
+		`rcuperf_param_nwriters "$1"` \
+		rcuperf.perf_runnable=1 \
+		rcuperf.shutdown=1 \
+		rcuperf.verbose=1
+}
-- 
2.5.2

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#1376976 — [PATCH tip/core/rcu 03/24] rcutorture: Expedited-GP batch progress access to torturing

This commit provides rcu_exp_batches_completed() and
rcu_exp_batches_completed_sched() functions to allow torture-test modules
to check how many expedited grace period batches have completed.
These are analogous to the existing rcu_batches_completed(),
rcu_batches_completed_bh(), and rcu_batches_completed_sched() functions.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 include/linux/rcutiny.h | 16 ++++++++++++++++
 include/linux/rcutree.h |  2 ++
 kernel/rcu/tree.c       | 22 ++++++++++++++++++++++
 3 files changed, 40 insertions(+)

diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 64809aea661c..93aea75029fb 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -149,6 +149,22 @@ static inline unsigned long rcu_batches_completed_sched(void)
 	return 0;
 }
 
+/*
+ * Return the number of expedited grace periods completed.
+ */
+static inline unsigned long rcu_exp_batches_completed(void)
+{
+	return 0;
+}
+
+/*
+ * Return the number of expedited sched grace periods completed.
+ */
+static inline unsigned long rcu_exp_batches_completed_sched(void)
+{
+	return 0;
+}
+
 static inline void rcu_force_quiescent_state(void)
 {
 }
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index ad1eda9fa4da..5043cb823fb2 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -87,6 +87,8 @@ unsigned long rcu_batches_started_sched(void);
 unsigned long rcu_batches_completed(void);
 unsigned long rcu_batches_completed_bh(void);
 unsigned long rcu_batches_completed_sched(void);
+unsigned long rcu_exp_batches_completed(void);
+unsigned long rcu_exp_batches_completed_sched(void);
 void show_rcu_gp_kthreads(void);
 
 void rcu_force_quiescent_state(void);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 531a328076bd..88df64087dfe 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -460,6 +460,28 @@ unsigned long rcu_batches_completed_bh(void)
 EXPORT_SYMBOL_GPL(rcu_batches_completed_bh);
 
 /*
+ * Return the number of RCU expedited batches completed thus far for
+ * debug & stats.  Odd numbers mean that a batch is in progress, even
+ * numbers mean idle.  The value returned will thus be roughly double
+ * the cumulative batches since boot.
+ */
+unsigned long rcu_exp_batches_completed(void)
+{
+	return rcu_state_p->expedited_sequence;
+}
+EXPORT_SYMBOL_GPL(rcu_exp_batches_completed);
+
+/*
+ * Return the number of RCU-sched expedited batches completed thus far
+ * for debug & stats.  Similar to rcu_exp_batches_completed().
+ */
+unsigned long rcu_exp_batches_completed_sched(void)
+{
+	return rcu_sched_state.expedited_sequence;
+}
+EXPORT_SYMBOL_GPL(rcu_exp_batches_completed_sched);
+
+/*
  * Force a quiescent state.
  */
 void rcu_force_quiescent_state(void)
-- 
2.5.2

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#1376978 — [PATCH tip/core/rcu 04/24] rcutorture: Add RCU grace-period performance tests

This commit adds a new rcuperf module that carries out simple performance
tests of RCU grace periods.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcu/Makefile  |   1 +
 kernel/rcu/rcuperf.c | 637 +++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/Kconfig.debug    |  33 +++
 3 files changed, 671 insertions(+)
 create mode 100644 kernel/rcu/rcuperf.c

diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile
index 032b2c015beb..18dfc485225c 100644
--- a/kernel/rcu/Makefile
+++ b/kernel/rcu/Makefile
@@ -5,6 +5,7 @@ KCOV_INSTRUMENT := n
 obj-y += update.o sync.o
 obj-$(CONFIG_SRCU) += srcu.o
 obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
+obj-$(CONFIG_RCU_PERF_TEST) += rcuperf.o
 obj-$(CONFIG_TREE_RCU) += tree.o
 obj-$(CONFIG_PREEMPT_RCU) += tree.o
 obj-$(CONFIG_TREE_RCU_TRACE) += tree_trace.o
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
new file mode 100644
index 000000000000..9d54a57bee7d
--- /dev/null
+++ b/kernel/rcu/rcuperf.c
@@ -0,0 +1,637 @@
+/*
+ * Read-Copy Update module-based performance-test facility
+ *
+ * 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, 2015
+ *
+ * Authors: Paul E. McKenney <paulmck@us.ibm.com>
+ */
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/err.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/rcupdate.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/completion.h>
+#include <linux/moduleparam.h>
+#include <linux/percpu.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/freezer.h>
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/stat.h>
+#include <linux/srcu.h>
+#include <linux/slab.h>
+#include <asm/byteorder.h>
+#include <linux/torture.h>
+#include <linux/vmalloc.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
+
+#define PERF_FLAG "-perf:"
+#define PERFOUT_STRING(s) \
+	pr_alert("%s" PERF_FLAG s "\n", perf_type)
+#define VERBOSE_PERFOUT_STRING(s) \
+	do { if (verbose) pr_alert("%s" PERF_FLAG " %s\n", perf_type, s); } while (0)
+#define VERBOSE_PERFOUT_ERRSTRING(s) \
+	do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0)
+
+torture_param(bool, gp_exp, true, "Use expedited GP wait primitives");
+torture_param(int, nreaders, -1, "Number of RCU reader threads");
+torture_param(int, nwriters, -1, "Number of RCU updater threads");
+torture_param(bool, shutdown, false, "Shutdown at end of performance tests.");
+torture_param(bool, verbose, true, "Enable verbose debugging printk()s");
+
+static char *perf_type = "rcu";
+module_param(perf_type, charp, 0444);
+MODULE_PARM_DESC(perf_type, "Type of RCU to performance-test (rcu, rcu_bh, ...)");
+
+static int nrealreaders;
+static int nrealwriters;
+static struct task_struct **writer_tasks;
+static struct task_struct **reader_tasks;
+static struct task_struct *shutdown_task;
+
+static u64 **writer_durations;
+static int *writer_n_durations;
+static atomic_t n_rcu_perf_reader_started;
+static atomic_t n_rcu_perf_writer_started;
+static atomic_t n_rcu_perf_writer_finished;
+static wait_queue_head_t shutdown_wq;
+static u64 t_rcu_perf_writer_started;
+static u64 t_rcu_perf_writer_finished;
+static unsigned long b_rcu_perf_writer_started;
+static unsigned long b_rcu_perf_writer_finished;
+
+static int rcu_perf_writer_state;
+#define RTWS_INIT		0
+#define RTWS_EXP_SYNC		1
+#define RTWS_SYNC		2
+#define RTWS_IDLE		2
+#define RTWS_STOPPING		3
+
+#define MAX_MEAS 10000
+#define MIN_MEAS 100
+
+#if defined(MODULE) || defined(CONFIG_RCU_PERF_TEST_RUNNABLE)
+#define RCUPERF_RUNNABLE_INIT 1
+#else
+#define RCUPERF_RUNNABLE_INIT 0
+#endif
+static int perf_runnable = RCUPERF_RUNNABLE_INIT;
+module_param(perf_runnable, int, 0444);
+MODULE_PARM_DESC(perf_runnable, "Start rcuperf at boot");
+
+/*
+ * Operations vector for selecting different types of tests.
+ */
+
+struct rcu_perf_ops {
+	int ptype;
+	void (*init)(void);
+	void (*cleanup)(void);
+	int (*readlock)(void);
+	void (*readunlock)(int idx);
+	unsigned long (*started)(void);
+	unsigned long (*completed)(void);
+	unsigned long (*exp_completed)(void);
+	void (*sync)(void);
+	void (*exp_sync)(void);
+	const char *name;
+};
+
+static struct rcu_perf_ops *cur_ops;
+
+/*
+ * Definitions for rcu perf testing.
+ */
+
+static int rcu_perf_read_lock(void) __acquires(RCU)
+{
+	rcu_read_lock();
+	return 0;
+}
+
+static void rcu_perf_read_unlock(int idx) __releases(RCU)
+{
+	rcu_read_unlock();
+}
+
+static unsigned long __maybe_unused rcu_no_completed(void)
+{
+	return 0;
+}
+
+static void rcu_sync_perf_init(void)
+{
+}
+
+static struct rcu_perf_ops rcu_ops = {
+	.ptype		= RCU_FLAVOR,
+	.init		= rcu_sync_perf_init,
+	.readlock	= rcu_perf_read_lock,
+	.readunlock	= rcu_perf_read_unlock,
+	.started	= rcu_batches_started,
+	.completed	= rcu_batches_completed,
+	.exp_completed	= rcu_exp_batches_completed,
+	.sync		= synchronize_rcu,
+	.exp_sync	= synchronize_rcu_expedited,
+	.name		= "rcu"
+};
+
+/*
+ * Definitions for rcu_bh perf testing.
+ */
+
+static int rcu_bh_perf_read_lock(void) __acquires(RCU_BH)
+{
+	rcu_read_lock_bh();
+	return 0;
+}
+
+static void rcu_bh_perf_read_unlock(int idx) __releases(RCU_BH)
+{
+	rcu_read_unlock_bh();
+}
+
+static struct rcu_perf_ops rcu_bh_ops = {
+	.ptype		= RCU_BH_FLAVOR,
+	.init		= rcu_sync_perf_init,
+	.readlock	= rcu_bh_perf_read_lock,
+	.readunlock	= rcu_bh_perf_read_unlock,
+	.started	= rcu_batches_started_bh,
+	.completed	= rcu_batches_completed_bh,
+	.exp_completed	= rcu_exp_batches_completed_sched,
+	.sync		= synchronize_rcu_bh,
+	.exp_sync	= synchronize_rcu_bh_expedited,
+	.name		= "rcu_bh"
+};
+
+/*
+ * Definitions for srcu perf testing.
+ */
+
+DEFINE_STATIC_SRCU(srcu_ctl_perf);
+static struct srcu_struct *srcu_ctlp = &srcu_ctl_perf;
+
+static int srcu_perf_read_lock(void) __acquires(srcu_ctlp)
+{
+	return srcu_read_lock(srcu_ctlp);
+}
+
+static void srcu_perf_read_unlock(int idx) __releases(srcu_ctlp)
+{
+	srcu_read_unlock(srcu_ctlp, idx);
+}
+
+static unsigned long srcu_perf_completed(void)
+{
+	return srcu_batches_completed(srcu_ctlp);
+}
+
+static void srcu_perf_synchronize(void)
+{
+	synchronize_srcu(srcu_ctlp);
+}
+
+static void srcu_perf_synchronize_expedited(void)
+{
+	synchronize_srcu_expedited(srcu_ctlp);
+}
+
+static struct rcu_perf_ops srcu_ops = {
+	.ptype		= SRCU_FLAVOR,
+	.init		= rcu_sync_perf_init,
+	.readlock	= srcu_perf_read_lock,
+	.readunlock	= srcu_perf_read_unlock,
+	.started	= NULL,
+	.completed	= srcu_perf_completed,
+	.exp_completed	= srcu_perf_completed,
+	.sync		= srcu_perf_synchronize,
+	.exp_sync	= srcu_perf_synchronize_expedited,
+	.name		= "srcu"
+};
+
+/*
+ * Definitions for sched perf testing.
+ */
+
+static int sched_perf_read_lock(void)
+{
+	preempt_disable();
+	return 0;
+}
+
+static void sched_perf_read_unlock(int idx)
+{
+	preempt_enable();
+}
+
+static struct rcu_perf_ops sched_ops = {
+	.ptype		= RCU_SCHED_FLAVOR,
+	.init		= rcu_sync_perf_init,
+	.readlock	= sched_perf_read_lock,
+	.readunlock	= sched_perf_read_unlock,
+	.started	= rcu_batches_started_sched,
+	.completed	= rcu_batches_completed_sched,
+	.exp_completed	= rcu_exp_batches_completed_sched,
+	.sync		= synchronize_sched,
+	.exp_sync	= synchronize_sched_expedited,
+	.name		= "sched"
+};
+
+#ifdef CONFIG_TASKS_RCU
+
+/*
+ * Definitions for RCU-tasks perf testing.
+ */
+
+static int tasks_perf_read_lock(void)
+{
+	return 0;
+}
+
+static void tasks_perf_read_unlock(int idx)
+{
+}
+
+static struct rcu_perf_ops tasks_ops = {
+	.ptype		= RCU_TASKS_FLAVOR,
+	.init		= rcu_sync_perf_init,
+	.readlock	= tasks_perf_read_lock,
+	.readunlock	= tasks_perf_read_unlock,
+	.started	= rcu_no_completed,
+	.completed	= rcu_no_completed,
+	.sync		= synchronize_rcu_tasks,
+	.exp_sync	= synchronize_rcu_tasks,
+	.name		= "tasks"
+};
+
+#define RCUPERF_TASKS_OPS &tasks_ops,
+
+static bool __maybe_unused torturing_tasks(void)
+{
+	return cur_ops == &tasks_ops;
+}
+
+#else /* #ifdef CONFIG_TASKS_RCU */
+
+#define RCUPERF_TASKS_OPS
+
+static bool __maybe_unused torturing_tasks(void)
+{
+	return false;
+}
+
+#endif /* #else #ifdef CONFIG_TASKS_RCU */
+
+/*
+ * If performance tests complete, wait for shutdown to commence.
+ */
+static void rcu_perf_wait_shutdown(void)
+{
+	cond_resched_rcu_qs();
+	if (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters)
+		return;
+	while (!torture_must_stop())
+		schedule_timeout_uninterruptible(1);
+}
+
+/*
+ * RCU perf reader kthread.  Repeatedly does empty RCU read-side
+ * critical section, minimizing update-side interference.
+ */
+static int
+rcu_perf_reader(void *arg)
+{
+	unsigned long flags;
+	int idx;
+
+	VERBOSE_PERFOUT_STRING("rcu_perf_reader task started");
+	set_user_nice(current, MAX_NICE);
+	atomic_inc(&n_rcu_perf_reader_started);
+
+	do {
+		local_irq_save(flags);
+		idx = cur_ops->readlock();
+		cur_ops->readunlock(idx);
+		local_irq_restore(flags);
+		rcu_perf_wait_shutdown();
+	} while (!torture_must_stop());
+	torture_kthread_stopping("rcu_perf_reader");
+	return 0;
+}
+
+/*
+ * RCU perf writer kthread.  Repeatedly does a grace period.
+ */
+static int
+rcu_perf_writer(void *arg)
+{
+	int i = 0;
+	int i_max;
+	long me = (long)arg;
+	bool started = false, done = false, alldone = false;
+	u64 t;
+	u64 *wdp;
+	u64 *wdpp = writer_durations[me];
+
+	VERBOSE_PERFOUT_STRING("rcu_perf_writer task started");
+	WARN_ON(rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp);
+	WARN_ON(rcu_gp_is_normal() && gp_exp);
+	WARN_ON(!wdpp);
+	t = ktime_get_mono_fast_ns();
+	if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) {
+		t_rcu_perf_writer_started = t;
+		if (gp_exp) {
+			b_rcu_perf_writer_started =
+				cur_ops->exp_completed() / 2;
+		} else {
+			b_rcu_perf_writer_started =
+				cur_ops->completed();
+		}
+	}
+
+	do {
+		wdp = &wdpp[i];
+		*wdp = ktime_get_mono_fast_ns();
+		if (gp_exp) {
+			rcu_perf_writer_state = RTWS_EXP_SYNC;
+			cur_ops->exp_sync();
+		} else {
+			rcu_perf_writer_state = RTWS_SYNC;
+			cur_ops->sync();
+		}
+		rcu_perf_writer_state = RTWS_IDLE;
+		t = ktime_get_mono_fast_ns();
+		*wdp = t - *wdp;
+		i_max = i;
+		if (!started &&
+		    atomic_read(&n_rcu_perf_writer_started) >= nrealwriters)
+			started = true;
+		if (!done && i >= MIN_MEAS) {
+			done = true;
+			pr_alert("%s" PERF_FLAG
+				 "rcu_perf_writer %ld has %d measurements\n",
+				 perf_type, me, MIN_MEAS);
+			if (atomic_inc_return(&n_rcu_perf_writer_finished) >=
+			    nrealwriters) {
+				PERFOUT_STRING("Test complete");
+				t_rcu_perf_writer_finished = t;
+				if (gp_exp) {
+					b_rcu_perf_writer_finished =
+						cur_ops->exp_completed() / 2;
+				} else {
+					b_rcu_perf_writer_finished =
+						cur_ops->completed();
+				}
+				smp_mb(); /* Assign before wake. */
+				wake_up(&shutdown_wq);
+			}
+		}
+		if (done && !alldone &&
+		    atomic_read(&n_rcu_perf_writer_finished) >= nrealwriters)
+			alldone = true;
+		if (started && !alldone && i < MAX_MEAS - 1)
+			i++;
+		rcu_perf_wait_shutdown();
+	} while (!torture_must_stop());
+	rcu_perf_writer_state = RTWS_STOPPING;
+	writer_n_durations[me] = i_max;
+	torture_kthread_stopping("rcu_perf_writer");
+	return 0;
+}
+
+static inline void
+rcu_perf_print_module_parms(struct rcu_perf_ops *cur_ops, const char *tag)
+{
+	pr_alert("%s" PERF_FLAG
+		 "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
+		 perf_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
+}
+
+static void
+rcu_perf_cleanup(void)
+{
+	int i;
+	int j;
+	int ngps = 0;
+	u64 *wdp;
+	u64 *wdpp;
+
+	if (torture_cleanup_begin())
+		return;
+
+	if (reader_tasks) {
+		for (i = 0; i < nrealreaders; i++)
+			torture_stop_kthread(rcu_perf_reader,
+					     reader_tasks[i]);
+		kfree(reader_tasks);
+	}
+
+	if (writer_tasks) {
+		for (i = 0; i < nrealwriters; i++) {
+			torture_stop_kthread(rcu_perf_writer,
+					     writer_tasks[i]);
+			if (!writer_n_durations)
+				continue;
+			j = writer_n_durations[i];
+			pr_alert("%s%s writer %d gps: %d\n",
+				 perf_type, PERF_FLAG, i, j);
+			ngps += j;
+		}
+		pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
+			 perf_type, PERF_FLAG,
+			 t_rcu_perf_writer_started, t_rcu_perf_writer_finished,
+			 t_rcu_perf_writer_finished -
+			 t_rcu_perf_writer_started,
+			 ngps,
+			 b_rcu_perf_writer_finished -
+			 b_rcu_perf_writer_started);
+		for (i = 0; i < nrealwriters; i++) {
+			if (!writer_durations)
+				break;
+			if (!writer_n_durations)
+				continue;
+			wdpp = writer_durations[i];
+			if (!wdpp)
+				continue;
+			for (j = 0; j <= writer_n_durations[i]; j++) {
+				wdp = &wdpp[j];
+				pr_alert("%s%s %4d writer-duration: %5d %llu\n",
+					perf_type, PERF_FLAG,
+					i, j, *wdp);
+				if (j % 100 == 0)
+					schedule_timeout_uninterruptible(1);
+			}
+			kfree(writer_durations[i]);
+		}
+		kfree(writer_tasks);
+		kfree(writer_durations);
+		kfree(writer_n_durations);
+	}
+
+	/* Do flavor-specific cleanup operations.  */
+	if (cur_ops->cleanup != NULL)
+		cur_ops->cleanup();
+
+	torture_cleanup_end();
+}
+
+/*
+ * Return the number if non-negative.  If -1, the number of CPUs.
+ * If less than -1, that much less than the number of CPUs, but
+ * at least one.
+ */
+static int compute_real(int n)
+{
+	int nr;
+
+	if (n >= 0) {
+		nr = n;
+	} else {
+		nr = num_online_cpus() + 1 + n;
+		if (nr <= 0)
+			nr = 1;
+	}
+	return nr;
+}
+
+/*
+ * RCU perf shutdown kthread.  Just waits to be awakened, then shuts
+ * down system.
+ */
+static int
+rcu_perf_shutdown(void *arg)
+{
+	do {
+		wait_event(shutdown_wq,
+			   atomic_read(&n_rcu_perf_writer_finished) >=
+			   nrealwriters);
+	} while (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters);
+	smp_mb(); /* Wake before output. */
+	rcu_perf_cleanup();
+	kernel_power_off();
+	return -EINVAL;
+}
+
+static int __init
+rcu_perf_init(void)
+{
+	long i;
+	int firsterr = 0;
+	static struct rcu_perf_ops *perf_ops[] = {
+		&rcu_ops, &rcu_bh_ops, &srcu_ops, &sched_ops,
+		RCUPERF_TASKS_OPS
+	};
+
+	if (!torture_init_begin(perf_type, verbose, &perf_runnable))
+		return -EBUSY;
+
+	/* Process args and tell the world that the perf'er is on the job. */
+	for (i = 0; i < ARRAY_SIZE(perf_ops); i++) {
+		cur_ops = perf_ops[i];
+		if (strcmp(perf_type, cur_ops->name) == 0)
+			break;
+	}
+	if (i == ARRAY_SIZE(perf_ops)) {
+		pr_alert("rcu-perf: invalid perf type: \"%s\"\n",
+			 perf_type);
+		pr_alert("rcu-perf types:");
+		for (i = 0; i < ARRAY_SIZE(perf_ops); i++)
+			pr_alert(" %s", perf_ops[i]->name);
+		pr_alert("\n");
+		firsterr = -EINVAL;
+		goto unwind;
+	}
+	if (cur_ops->init)
+		cur_ops->init();
+
+	nrealwriters = compute_real(nwriters);
+	nrealreaders = compute_real(nreaders);
+	atomic_set(&n_rcu_perf_reader_started, 0);
+	atomic_set(&n_rcu_perf_writer_started, 0);
+	atomic_set(&n_rcu_perf_writer_finished, 0);
+	rcu_perf_print_module_parms(cur_ops, "Start of test");
+
+	/* Start up the kthreads. */
+
+	if (shutdown) {
+		init_waitqueue_head(&shutdown_wq);
+		firsterr = torture_create_kthread(rcu_perf_shutdown, NULL,
+						  shutdown_task);
+		if (firsterr)
+			goto unwind;
+		schedule_timeout_uninterruptible(1);
+	}
+	reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
+			       GFP_KERNEL);
+	if (reader_tasks == NULL) {
+		VERBOSE_PERFOUT_ERRSTRING("out of memory");
+		firsterr = -ENOMEM;
+		goto unwind;
+	}
+	for (i = 0; i < nrealreaders; i++) {
+		firsterr = torture_create_kthread(rcu_perf_reader, NULL,
+						  reader_tasks[i]);
+		if (firsterr)
+			goto unwind;
+	}
+	while (atomic_read(&n_rcu_perf_reader_started) < nrealreaders)
+		schedule_timeout_uninterruptible(1);
+	writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
+			       GFP_KERNEL);
+	writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
+				   GFP_KERNEL);
+	writer_n_durations =
+		kcalloc(nrealwriters, sizeof(*writer_n_durations),
+			GFP_KERNEL);
+	if (!writer_tasks || !writer_durations || !writer_n_durations) {
+		VERBOSE_PERFOUT_ERRSTRING("out of memory");
+		firsterr = -ENOMEM;
+		goto unwind;
+	}
+	for (i = 0; i < nrealwriters; i++) {
+		writer_durations[i] =
+			kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
+				GFP_KERNEL);
+		if (!writer_durations[i])
+			goto unwind;
+		firsterr = torture_create_kthread(rcu_perf_writer, (void *)i,
+						  writer_tasks[i]);
+		if (firsterr)
+			goto unwind;
+	}
+	torture_init_end();
+	return 0;
+
+unwind:
+	torture_init_end();
+	rcu_perf_cleanup();
+	return firsterr;
+}
+
+module_init(rcu_perf_init);
+module_exit(rcu_perf_cleanup);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1e9a607534ca..f4b797a690ba 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1289,6 +1289,39 @@ config TORTURE_TEST
 	tristate
 	default n
 
+config RCU_PERF_TEST
+	tristate "performance tests for RCU"
+	depends on DEBUG_KERNEL
+	select TORTURE_TEST
+	select SRCU
+	select TASKS_RCU
+	default n
+	help
+	  This option provides a kernel module that runs performance
+	  tests on the RCU infrastructure.  The kernel module may be built
+	  after the fact on the running kernel to be tested, if desired.
+
+	  Say Y here if you want RCU performance tests to be built into
+	  the kernel.
+	  Say M if you want the RCU performance tests to build as a module.
+	  Say N if you are unsure.
+
+config RCU_PERF_TEST_RUNNABLE
+	bool "performance tests for RCU runnable by default"
+	depends on RCU_PERF_TEST = y
+	default n
+	help
+	  This option provides a way to build the RCU performance tests
+	  directly into the kernel without them starting up at boot time.
+	  You can use /sys/module to manually override this setting.
+	  This /proc file is available only when the RCU performance
+	  tests have been built into the kernel.
+
+	  Say Y here if you want the RCU performance tests to start during
+	  boot (you probably don't).
+	  Say N here if you want the RCU performance tests to start only
+	  after being manually enabled via /sys/module.
+
 config RCU_TORTURE_TEST
 	tristate "torture tests for RCU"
 	depends on DEBUG_KERNEL
-- 
2.5.2

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#1376982 — [PATCH tip/core/rcu 05/24] rcutorture: Documentation for rcuperf kernel parameters

This commit adds documentation for the new rcuperf module's kernel
boot parameters.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 Documentation/kernel-parameters.txt | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ecc74fa4bfde..951af481da5a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3284,6 +3284,38 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Lazy RCU callbacks are those which RCU can
 			prove do nothing more than free memory.
 
+	rcuperf.gp_exp= [KNL]
+			Measure performance of expedited synchronous
+			grace-period primitives.
+
+	rcuperf.nreaders= [KNL]
+			Set number of RCU readers.  The value -1 selects
+			N, where N is the number of CPUs.  A value
+			"n" less than -1 selects N-n+1, where N is again
+			the number of CPUs.  For example, -2 selects N
+			(the number of CPUs), -3 selects N+1, and so on.
+			A value of "n" less than or equal to -N selects
+			a single reader.
+
+	rcuperf.nwriters= [KNL]
+			Set number of RCU writers.  The values operate
+			the same as for rcuperf.nreaders.
+			N, where N is the number of CPUs
+
+	rcuperf.perf_runnable= [BOOT]
+			Start rcuperf running at boot time.
+
+	rcuperf.shutdown= [KNL]
+			Shut the system down after performance tests
+			complete.  This is useful for hands-off automated
+			testing.
+
+	rcuperf.perf_type= [KNL]
+			Specify the RCU implementation to test.
+
+	rcuperf.verbose= [KNL]
+			Enable additional printk() statements.
+
 	rcutorture.cbflood_inter_holdoff= [KNL]
 			Set holdoff time (jiffies) between successive
 			callback-flood tests.
-- 
2.5.2

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