[Qemu-devel] [PATCH 3/8] rcu: add rcutorture

[Paolo Bonzini <pbonzini@redhat.com>]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 tests/Makefile     |   6 +-
 tests/rcutorture.c | 447 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 util/rcu.c         |   1 -
 3 files changed, 452 insertions(+), 2 deletions(-)
 create mode 100644 tests/rcutorture.c

diff --git a/tests/Makefile b/tests/Makefile
index 47ba143..980c0ec 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -63,6 +63,8 @@ gcov-files-test-tls-y =
 check-unit-y += tests/test-int128$(EXESUF)
 # all code tested by test-int128 is inside int128.h
 gcov-files-test-int128-y =
+check-unit-y += tests/rcutorture$(EXESUF)
+gcov-files-rcutorture-y = util/rcu.c
 check-unit-y += tests/test-bitops$(EXESUF)
 check-unit-$(CONFIG_HAS_GLIB_SUBPROCESS_TESTS) += tests/test-qdev-global-props$(EXESUF)
 check-unit-y += tests/check-qom-interface$(EXESUF)
@@ -226,7 +228,8 @@ test-obj-y = tests/check-qint.o tests/check-qstring.o tests/check-qdict.o \
 	tests/test-qmp-input-visitor.o tests/test-qmp-input-strict.o \
 	tests/test-qmp-commands.o tests/test-visitor-serialization.o \
 	tests/test-x86-cpuid.o tests/test-mul64.o tests/test-int128.o \
-	tests/test-opts-visitor.o tests/test-qmp-event.o tests/test-tls.o
+	tests/test-opts-visitor.o tests/test-qmp-event.o tests/test-tls.o \
+	tests/rcutorture.o
 
 test-qapi-obj-y = tests/test-qapi-visit.o tests/test-qapi-types.o \
 		  tests/test-qapi-event.o
@@ -256,6 +259,7 @@ tests/test-xbzrle$(EXESUF): tests/test-xbzrle.o migration/xbzrle.o page_cache.o
 tests/test-cutils$(EXESUF): tests/test-cutils.o util/cutils.o
 tests/test-int128$(EXESUF): tests/test-int128.o
 tests/test-tls$(EXESUF): tests/test-tls.o libqemuutil.a
+tests/rcutorture$(EXESUF): tests/rcutorture.o libqemuutil.a
 
 tests/test-qdev-global-props$(EXESUF): tests/test-qdev-global-props.o \
 	hw/core/qdev.o hw/core/qdev-properties.o hw/core/hotplug.o\
diff --git a/tests/rcutorture.c b/tests/rcutorture.c
new file mode 100644
index 0000000..cda7458
--- /dev/null
+++ b/tests/rcutorture.c
@@ -0,0 +1,447 @@
+/*
+ * rcutorture.c: simple user-level performance/stress test of RCU.
+ *
+ * Usage:
+ *     ./rcu <nreaders> rperf [ <seconds> ]
+ *         Run a read-side performance test with the specified
+ *         number of readers for <seconds> seconds.
+ *     ./rcu <nupdaters> uperf [ <seconds> ]
+ *         Run an update-side performance test with the specified
+ *         number of updaters and specified duration.
+ *     ./rcu <nreaders> perf [ <seconds> ]
+ *         Run a combined read/update performance test with the specified
+ *         number of readers and one updater and specified duration.
+ *
+ * The above tests produce output as follows:
+ *
+ * n_reads: 46008000  n_updates: 146026  nreaders: 2  nupdaters: 1 duration: 1
+ * ns/read: 43.4707  ns/update: 6848.1
+ *
+ * The first line lists the total number of RCU reads and updates executed
+ * during the test, the number of reader threads, the number of updater
+ * threads, and the duration of the test in seconds.  The second line
+ * lists the average duration of each type of operation in nanoseconds,
+ * or "nan" if the corresponding type of operation was not performed.
+ *
+ *     ./rcu <nreaders> stress [ <seconds> ]
+ *         Run a stress test with the specified number of readers and
+ *         one updater.
+ *
+ * This test produces output as follows:
+ *
+ * n_reads: 114633217  n_updates: 3903415  n_mberror: 0
+ * rcu_stress_count: 114618391 14826 0 0 0 0 0 0 0 0 0
+ *
+ * The first line lists the number of RCU read and update operations
+ * executed, followed by the number of memory-ordering violations
+ * (which will be zero in a correct RCU implementation).  The second
+ * line lists the number of readers observing progressively more stale
+ * data.  A correct RCU implementation will have all but the first two
+ * numbers non-zero.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (c) 2008 Paul E. McKenney, IBM Corporation.
+ */
+
+/*
+ * Test variables.
+ */
+
+#include <glib.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "qemu/atomic.h"
+#include "qemu/rcu.h"
+#include "qemu/compiler.h"
+#include "qemu/thread.h"
+
+long long n_reads = 0LL;
+long n_updates = 0L;
+int nthreadsrunning;
+
+char argsbuf[64];
+
+#define GOFLAG_INIT 0
+#define GOFLAG_RUN  1
+#define GOFLAG_STOP 2
+
+static volatile int goflag = GOFLAG_INIT;
+
+#define RCU_READ_RUN 1000
+
+#define NR_THREADS 100
+static QemuThread threads[NR_THREADS];
+static struct rcu_reader_data *data[NR_THREADS];
+static int n_threads;
+
+static void create_thread(void *(*func)(void *))
+{
+    if (n_threads >= NR_THREADS) {
+        fprintf(stderr, "Thread limit of %d exceeded!\n", NR_THREADS);
+        exit(-1);
+    }
+    qemu_thread_create(&threads[n_threads], "test", func, &data[n_threads],
+                       QEMU_THREAD_JOINABLE);
+    n_threads++;
+}
+
+static void wait_all_threads(void)
+{
+    int i;
+
+    for (i = 0; i < n_threads; i++) {
+        qemu_thread_join(&threads[i]);
+    }
+    n_threads = 0;
+}
+
+/*
+ * Performance test.
+ */
+
+static void *rcu_read_perf_test(void *arg)
+{
+    int i;
+    long long n_reads_local = 0;
+
+    rcu_register_thread();
+
+    *(struct rcu_reader_data **)arg = &rcu_reader;
+    atomic_inc(&nthreadsrunning);
+    while (goflag == GOFLAG_INIT) {
+        g_usleep(1000);
+    }
+    while (goflag == GOFLAG_RUN) {
+        for (i = 0; i < RCU_READ_RUN; i++) {
+            rcu_read_lock();
+            rcu_read_unlock();
+        }
+        n_reads_local += RCU_READ_RUN;
+    }
+    atomic_add(&n_reads, n_reads_local);
+
+    rcu_unregister_thread();
+    return NULL;
+}
+
+static void *rcu_update_perf_test(void *arg)
+{
+    long long n_updates_local = 0;
+
+    rcu_register_thread();
+
+    *(struct rcu_reader_data **)arg = &rcu_reader;
+    atomic_inc(&nthreadsrunning);
+    while (goflag == GOFLAG_INIT) {
+        g_usleep(1000);
+    }
+    while (goflag == GOFLAG_RUN) {
+        synchronize_rcu();
+        n_updates_local++;
+    }
+    atomic_add(&n_updates, n_updates_local);
+
+    rcu_unregister_thread();
+    return NULL;
+}
+
+static void perftestinit(void)
+{
+    nthreadsrunning = 0;
+}
+
+static void perftestrun(int nthreads, int duration, int nreaders, int nupdaters)
+{
+    while (atomic_read(&nthreadsrunning) < nthreads) {
+        g_usleep(1000);
+    }
+    goflag = GOFLAG_RUN;
+    sleep(duration);
+    goflag = GOFLAG_STOP;
+    wait_all_threads();
+    printf("n_reads: %lld  n_updates: %ld  nreaders: %d  nupdaters: %d duration: %d\n",
+           n_reads, n_updates, nreaders, nupdaters, duration);
+    printf("ns/read: %g  ns/update: %g\n",
+           ((duration * 1000*1000*1000.*(double)nreaders) /
+        (double)n_reads),
+           ((duration * 1000*1000*1000.*(double)nupdaters) /
+        (double)n_updates));
+    exit(0);
+}
+
+static void perftest(int nreaders, int duration)
+{
+    int i;
+
+    perftestinit();
+    for (i = 0; i < nreaders; i++) {
+        create_thread(rcu_read_perf_test);
+    }
+    create_thread(rcu_update_perf_test);
+    perftestrun(i + 1, duration, nreaders, 1);
+}
+
+static void rperftest(int nreaders, int duration)
+{
+    int i;
+
+    perftestinit();
+    for (i = 0; i < nreaders; i++) {
+        create_thread(rcu_read_perf_test);
+    }
+    perftestrun(i, duration, nreaders, 0);
+}
+
+static void uperftest(int nupdaters, int duration)
+{
+    int i;
+
+    perftestinit();
+    for (i = 0; i < nupdaters; i++) {
+        create_thread(rcu_update_perf_test);
+    }
+    perftestrun(i, duration, 0, nupdaters);
+}
+
+/*
+ * Stress test.
+ */
+
+#define RCU_STRESS_PIPE_LEN 10
+
+struct rcu_stress {
+    int pipe_count;
+    int mbtest;
+};
+
+struct rcu_stress rcu_stress_array[RCU_STRESS_PIPE_LEN] = { { 0 } };
+struct rcu_stress *rcu_stress_current;
+int rcu_stress_idx;
+
+int n_mberror;
+long long rcu_stress_count[RCU_STRESS_PIPE_LEN + 1];
+
+
+static void *rcu_read_stress_test(void *arg)
+{
+    int i;
+    int itercnt = 0;
+    struct rcu_stress *p;
+    int pc;
+    long long n_reads_local = 0;
+    volatile int garbage;
+
+    rcu_register_thread();
+
+    *(struct rcu_reader_data **)arg = &rcu_reader;
+    while (goflag == GOFLAG_INIT) {
+        g_usleep(1000);
+    }
+    while (goflag == GOFLAG_RUN) {
+        rcu_read_lock();
+        p = atomic_rcu_read(&rcu_stress_current);
+        if (p->mbtest == 0) {
+            n_mberror++;
+        }
+        for (i = 0; i < 100; i++) {
+            garbage++;
+        }
+        pc = p->pipe_count;
+        rcu_read_unlock();
+        if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) {
+            pc = RCU_STRESS_PIPE_LEN;
+        }
+        atomic_inc(&rcu_stress_count[pc]);
+        n_reads_local++;
+        if ((++itercnt % 0x1000) == 0) {
+            synchronize_rcu();
+        }
+    }
+    atomic_add(&n_reads, n_reads_local);
+
+    rcu_unregister_thread();
+    return NULL;
+}
+
+static void *rcu_update_stress_test(void *arg)
+{
+    int i;
+    struct rcu_stress *p;
+
+    rcu_register_thread();
+
+    *(struct rcu_reader_data **)arg = &rcu_reader;
+    while (goflag == GOFLAG_INIT) {
+        g_usleep(1000);
+    }
+    while (goflag == GOFLAG_RUN) {
+        i = rcu_stress_idx + 1;
+        if (i >= RCU_STRESS_PIPE_LEN) {
+            i = 0;
+        }
+        p = &rcu_stress_array[i];
+        p->mbtest = 0;
+        smp_mb();
+        p->pipe_count = 0;
+        p->mbtest = 1;
+        atomic_rcu_set(&rcu_stress_current, p);
+        rcu_stress_idx = i;
+        for (i = 0; i < RCU_STRESS_PIPE_LEN; i++)
+            if (i != rcu_stress_idx) {
+                rcu_stress_array[i].pipe_count++;
+            }
+        synchronize_rcu();
+        n_updates++;
+    }
+
+    rcu_unregister_thread();
+    return NULL;
+}
+
+static void *rcu_fake_update_stress_test(void *arg)
+{
+    rcu_register_thread();
+
+    *(struct rcu_reader_data **)arg = &rcu_reader;
+    while (goflag == GOFLAG_INIT) {
+        g_usleep(1000);
+    }
+    while (goflag == GOFLAG_RUN) {
+        synchronize_rcu();
+        g_usleep(1000);
+    }
+
+    rcu_unregister_thread();
+    return NULL;
+}
+
+static void stresstest(int nreaders, int duration)
+{
+    int i;
+
+    rcu_stress_current = &rcu_stress_array[0];
+    rcu_stress_current->pipe_count = 0;
+    rcu_stress_current->mbtest = 1;
+    for (i = 0; i < nreaders; i++) {
+        create_thread(rcu_read_stress_test);
+    }
+    create_thread(rcu_update_stress_test);
+    for (i = 0; i < 5; i++) {
+        create_thread(rcu_fake_update_stress_test);
+    }
+    goflag = GOFLAG_RUN;
+    sleep(duration);
+    goflag = GOFLAG_STOP;
+    wait_all_threads();
+    printf("n_reads: %lld  n_updates: %ld  n_mberror: %d\n",
+           n_reads, n_updates, n_mberror);
+    printf("rcu_stress_count:");
+    for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++) {
+        printf(" %lld", rcu_stress_count[i]);
+    }
+    printf("\n");
+    exit(0);
+}
+
+/* GTest interface */
+
+static void gtest_stress(int nreaders, int duration)
+{
+    int i;
+
+    rcu_stress_current = &rcu_stress_array[0];
+    rcu_stress_current->pipe_count = 0;
+    rcu_stress_current->mbtest = 1;
+    for (i = 0; i < nreaders; i++) {
+        create_thread(rcu_read_stress_test);
+    }
+    create_thread(rcu_update_stress_test);
+    for (i = 0; i < 5; i++) {
+        create_thread(rcu_fake_update_stress_test);
+    }
+    goflag = GOFLAG_RUN;
+    sleep(duration);
+    goflag = GOFLAG_STOP;
+    wait_all_threads();
+    g_assert_cmpint(n_mberror, ==, 0);
+    for (i = 2; i <= RCU_STRESS_PIPE_LEN; i++) {
+        g_assert_cmpint(rcu_stress_count[i], ==, 0);
+    }
+}
+
+static void gtest_stress_1_1(void)
+{
+    gtest_stress(1, 1);
+}
+
+static void gtest_stress_10_1(void)
+{
+    gtest_stress(10, 1);
+}
+
+static void gtest_stress_1_5(void)
+{
+    gtest_stress(1, 5);
+}
+
+static void gtest_stress_10_5(void)
+{
+    gtest_stress(10, 5);
+}
+
+/*
+ * Mainprogram.
+ */
+
+static void usage(int argc, char *argv[])
+{
+    fprintf(stderr, "Usage: %s [nreaders [ perf | stress ] ]\n", argv[0]);
+    exit(-1);
+}
+
+int main(int argc, char *argv[])
+{
+    int nreaders = 1;
+    int duration = 1;
+
+    if (argc >= 2 && argv[1][0] == '-') {
+        g_test_init(&argc, &argv, NULL);
+        g_test_add_func("/rcu/torture/short/1reader", gtest_stress_1_1);
+        g_test_add_func("/rcu/torture/short/10readers", gtest_stress_10_1);
+        g_test_add_func("/rcu/torture/long/1reader", gtest_stress_1_5);
+        g_test_add_func("/rcu/torture/long/10readers", gtest_stress_10_5);
+        return g_test_run();
+    }
+
+    if (argc >= 2) {
+        nreaders = strtoul(argv[1], NULL, 0);
+    }
+    if (argc > 3) {
+        duration = strtoul(argv[3], NULL, 0);
+    }
+    if (argc < 3 || strcmp(argv[2], "stress") == 0) {
+        stresstest(nreaders, duration);
+    } else if (strcmp(argv[2], "rperf") == 0) {
+        rperftest(nreaders, duration);
+    } else if (strcmp(argv[2], "uperf") == 0) {
+        uperftest(nreaders, duration);
+    } else if (strcmp(argv[2], "perf") == 0) {
+        perftest(nreaders, duration);
+    }
+    usage(argc, argv);
+    return 0;
+}
diff --git a/util/rcu.c b/util/rcu.c
index f8f52ae..8df16d9 100644
--- a/util/rcu.c
+++ b/util/rcu.c
@@ -169,5 +169,4 @@ static void __attribute__((__constructor__)) rcu_init(void)
 {
     qemu_mutex_init(&rcu_gp_lock);
     qemu_event_init(&rcu_gp_event, true);
-    rcu_register_thread();
 }
-- 
1.8.3.1