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authorDavid Howells <dhowells@redhat.com>2019-08-13 23:09:38 +0000
committerJohannes Weiner <hannes@cmpxchg.org>2019-08-13 23:09:38 +0000
commit6fe87f1ffec0ede0423b8b8dc40598079356437a (patch)
tree976bfe75722999b5e3cf3e8d224cf9a6822f9cc8
parentc7324dd1dcaeb609aa7be4b8af516174932c0cb7 (diff)
mutex subsystem, synchro-test module
The attached patch adds a module for testing and benchmarking mutexes, semaphores and R/W semaphores. Using it is simple: insmod synchro-test.ko <args> It will exit with error ENOANO after running the tests and printing the results to the kernel console log. The available arguments are: (*) mx=N Start up to N mutex thrashing threads, where N is at most 20. All will try and thrash the same mutex. (*) sm=N Start up to N counting semaphore thrashing threads, where N is at most 20. All will try and thrash the same semaphore. (*) ism=M Initialise the counting semaphore with M, where M is any positive integer greater than zero. The default is 4. (*) rd=N (*) wr=O (*) dg=P Start up to N reader thrashing threads, O writer thrashing threads and P downgrader thrashing threads, where N, O and P are at most 20 apiece. All will try and thrash the same read/write semaphore. (*) elapse=N Run the tests for N seconds. The default is 5. (*) load=N Each thread delays for N uS whilst holding the lock. The dfault is 0. (*) interval=N Each thread delays for N uS whilst not holding the lock. The default is 0. (*) do_sched=1 Each thread will call schedule if required after each iteration. (*) v=1 Print more verbose information, including a thread iteration distribution list. The module should be enabled by turning on CONFIG_DEBUG_SYNCHRO_TEST to "m". [randy.dunlap@oracle.com: fix build errors, add <sched.h> header file] [akpm@linux-foundation.org: remove smp_lock.h inclusion] [viro@ZenIV.linux.org.uk: kill daemonize() calls] [rdunlap@xenotime.net: fix printk format warrnings] [walken@google.com: add spinlock test] [walken@google.com: document default load and interval values] Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--Documentation/synchro-test.txt59
-rw-r--r--kernel/Makefile1
-rw-r--r--kernel/synchro-test.c585
-rw-r--r--lib/Kconfig.debug14
4 files changed, 659 insertions, 0 deletions
diff --git a/Documentation/synchro-test.txt b/Documentation/synchro-test.txt
new file mode 100644
index 000000000000..554709478e1f
--- /dev/null
+++ b/Documentation/synchro-test.txt
@@ -0,0 +1,59 @@
+The synchro-test.ko module can be used for testing and benchmarking mutexes,
+semaphores and R/W semaphores.
+
+The module is compiled by setting CONFIG_DEBUG_SYNCHRO_TEST to "m" when
+configuring the kernel.
+
+Using it is simple:
+
+ insmod synchro-test.ko <args>
+
+It will exit with error ENOANO after running the tests and printing the
+results to the kernel console log.
+
+The available arguments are:
+
+ (*) mx=N
+
+ Start up to N mutex thrashing threads, where N is at most 20. All will
+ try and thrash the same mutex.
+
+ (*) sm=N
+
+ Start up to N counting semaphore thrashing threads, where N is at most
+ 20. All will try and thrash the same semaphore.
+
+ (*) ism=M
+
+ Initialise the counting semaphore with M, where M is any positive
+ integer greater than zero. The default is 4.
+
+ (*) rd=N
+ (*) wr=O
+ (*) dg=P
+
+ Start up to N reader thrashing threads, O writer thrashing threads and
+ P downgrader thrashing threads, where N, O and P are at most 20
+ apiece. All will try and thrash the same read/write semaphore.
+
+ (*) elapse=N
+
+ Run the tests for N seconds. The default is 5.
+
+ (*) load=N
+
+ Each thread delays for N uS whilst holding the lock. The default is 2.
+
+ (*) interval=N
+
+ Each thread delays for N uS whilst not holding the lock. The default
+ is 2.
+
+ (*) do_sched=1
+
+ Each thread will call schedule if required after each iteration.
+
+ (*) v=1
+
+ Print more verbose information, including a thread iteration
+ distribution list.
diff --git a/kernel/Makefile b/kernel/Makefile
index e4dc0e7907b5..7d9ae072dce4 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -71,6 +71,7 @@ obj-$(CONFIG_CGROUPS) += cgroup/
obj-$(CONFIG_UTS_NS) += utsname.o
obj-$(CONFIG_USER_NS) += user_namespace.o
obj-$(CONFIG_PID_NS) += pid_namespace.o
+obj-$(CONFIG_DEBUG_SYNCHRO_TEST) += synchro-test.o
obj-$(CONFIG_IKCONFIG) += configs.o
obj-$(CONFIG_IKHEADERS) += kheaders.o
obj-$(CONFIG_SMP) += stop_machine.o
diff --git a/kernel/synchro-test.c b/kernel/synchro-test.c
new file mode 100644
index 000000000000..570709b96986
--- /dev/null
+++ b/kernel/synchro-test.c
@@ -0,0 +1,585 @@
+/* synchro-test.c: run some threads to test the synchronisation primitives
+ *
+ * Copyright (C) 2005, 2006 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * 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.
+ *
+ * The module should be run as something like:
+ *
+ * insmod synchro-test.ko rd=2 wr=2
+ * insmod synchro-test.ko mx=1
+ * insmod synchro-test.ko sm=2 ism=1
+ * insmod synchro-test.ko sm=2 ism=2
+ *
+ * See Documentation/synchro-test.txt for more information.
+ */
+
+#include <linux/module.h>
+#include <linux/poll.h>
+#include <linux/moduleparam.h>
+#include <linux/sched.h>
+#include <linux/stat.h>
+#include <linux/init.h>
+#include <asm/atomic.h>
+#include <linux/personality.h>
+#include <linux/delay.h>
+#include <linux/timer.h>
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <linux/kthread.h>
+
+#define MAX_THREADS 64
+
+/*
+ * Turn on self-validation if we do a one-shot boot-time test:
+ */
+#ifndef MODULE
+# define VALIDATE_OPERATORS
+#endif
+
+static int numsp;
+static int nummx;
+static int numsm, seminit = 4;
+static int numrd, numwr, numdg;
+static int elapse = 5, load = 2, do_sched, interval = 2;
+static int verbose = 0;
+
+MODULE_AUTHOR("David Howells");
+MODULE_DESCRIPTION("Synchronisation primitive test demo");
+MODULE_LICENSE("GPL");
+
+module_param_named(v, verbose, int, 0);
+MODULE_PARM_DESC(verbose, "Verbosity");
+
+module_param_named(sp, numsp, int, 0);
+MODULE_PARM_DESC(numsp, "Number of spinlock threads");
+
+module_param_named(mx, nummx, int, 0);
+MODULE_PARM_DESC(nummx, "Number of mutex threads");
+
+module_param_named(sm, numsm, int, 0);
+MODULE_PARM_DESC(numsm, "Number of semaphore threads");
+
+module_param_named(ism, seminit, int, 0);
+MODULE_PARM_DESC(seminit, "Initial semaphore value");
+
+module_param_named(rd, numrd, int, 0);
+MODULE_PARM_DESC(numrd, "Number of reader threads");
+
+module_param_named(wr, numwr, int, 0);
+MODULE_PARM_DESC(numwr, "Number of writer threads");
+
+module_param_named(dg, numdg, int, 0);
+MODULE_PARM_DESC(numdg, "Number of downgrader threads");
+
+module_param(elapse, int, 0);
+MODULE_PARM_DESC(elapse, "Number of seconds to run for");
+
+module_param(load, int, 0);
+MODULE_PARM_DESC(load, "Length of load in uS");
+
+module_param(interval, int, 0);
+MODULE_PARM_DESC(interval, "Length of interval in uS before re-getting lock");
+
+module_param(do_sched, int, 0);
+MODULE_PARM_DESC(do_sched, "True if each thread should schedule regularly");
+
+/* the semaphores under test */
+static spinlock_t ____cacheline_aligned spinlock;
+static struct mutex ____cacheline_aligned mutex;
+static struct semaphore ____cacheline_aligned sem;
+static struct rw_semaphore ____cacheline_aligned rwsem;
+
+static atomic_t ____cacheline_aligned do_stuff = ATOMIC_INIT(0);
+
+#ifdef VALIDATE_OPERATORS
+static atomic_t ____cacheline_aligned spinlocks = ATOMIC_INIT(0);
+static atomic_t ____cacheline_aligned mutexes = ATOMIC_INIT(0);
+static atomic_t ____cacheline_aligned semaphores = ATOMIC_INIT(0);
+static atomic_t ____cacheline_aligned readers = ATOMIC_INIT(0);
+static atomic_t ____cacheline_aligned writers = ATOMIC_INIT(0);
+#endif
+
+static unsigned int ____cacheline_aligned spinlocks_taken [MAX_THREADS];
+static unsigned int ____cacheline_aligned mutexes_taken [MAX_THREADS];
+static unsigned int ____cacheline_aligned semaphores_taken [MAX_THREADS];
+static unsigned int ____cacheline_aligned reads_taken [MAX_THREADS];
+static unsigned int ____cacheline_aligned writes_taken [MAX_THREADS];
+static unsigned int ____cacheline_aligned downgrades_taken [MAX_THREADS];
+
+static struct completion ____cacheline_aligned sp_comp[MAX_THREADS];
+static struct completion ____cacheline_aligned mx_comp[MAX_THREADS];
+static struct completion ____cacheline_aligned sm_comp[MAX_THREADS];
+static struct completion ____cacheline_aligned rd_comp[MAX_THREADS];
+static struct completion ____cacheline_aligned wr_comp[MAX_THREADS];
+static struct completion ____cacheline_aligned dg_comp[MAX_THREADS];
+
+static struct timer_list ____cacheline_aligned timer;
+
+#define ACCOUNT(var, N) var##_taken[N]++;
+
+#ifdef VALIDATE_OPERATORS
+#define TRACK(var, dir) atomic_##dir(&(var))
+
+#define CHECK(var, cond, val) \
+do { \
+ int x = atomic_read(&(var)); \
+ if (unlikely(!(x cond (val)))) \
+ printk("check [%s %s %d, == %d] failed in %s\n", \
+ #var, #cond, (val), x, __func__); \
+} while (0)
+
+#else
+#define TRACK(var, dir) do {} while(0)
+#define CHECK(var, cond, val) do {} while(0)
+#endif
+
+static inline void do_spin_lock(unsigned int N)
+{
+ spin_lock(&spinlock);
+
+ ACCOUNT(spinlocks, N);
+ TRACK(spinlocks, inc);
+ CHECK(spinlocks, ==, 1);
+}
+
+static inline void do_spin_unlock(unsigned int N)
+{
+ CHECK(spinlocks, ==, 1);
+ TRACK(spinlocks, dec);
+
+ spin_unlock(&spinlock);
+}
+
+static inline void do_mutex_lock(unsigned int N)
+{
+ mutex_lock(&mutex);
+
+ ACCOUNT(mutexes, N);
+ TRACK(mutexes, inc);
+ CHECK(mutexes, ==, 1);
+}
+
+static inline void do_mutex_unlock(unsigned int N)
+{
+ CHECK(mutexes, ==, 1);
+ TRACK(mutexes, dec);
+
+ mutex_unlock(&mutex);
+}
+
+static inline void do_down(unsigned int N)
+{
+ CHECK(mutexes, <, seminit);
+
+ down(&sem);
+
+ ACCOUNT(semaphores, N);
+ TRACK(semaphores, inc);
+}
+
+static inline void do_up(unsigned int N)
+{
+ CHECK(semaphores, >, 0);
+ TRACK(semaphores, dec);
+
+ up(&sem);
+}
+
+static inline void do_down_read(unsigned int N)
+{
+ down_read(&rwsem);
+
+ ACCOUNT(reads, N);
+ TRACK(readers, inc);
+ CHECK(readers, >, 0);
+ CHECK(writers, ==, 0);
+}
+
+static inline void do_up_read(unsigned int N)
+{
+ CHECK(readers, >, 0);
+ CHECK(writers, ==, 0);
+ TRACK(readers, dec);
+
+ up_read(&rwsem);
+}
+
+static inline void do_down_write(unsigned int N)
+{
+ down_write(&rwsem);
+
+ ACCOUNT(writes, N);
+ TRACK(writers, inc);
+ CHECK(writers, ==, 1);
+ CHECK(readers, ==, 0);
+}
+
+static inline void do_up_write(unsigned int N)
+{
+ CHECK(writers, ==, 1);
+ CHECK(readers, ==, 0);
+ TRACK(writers, dec);
+
+ up_write(&rwsem);
+}
+
+static inline void do_downgrade_write(unsigned int N)
+{
+ CHECK(writers, ==, 1);
+ CHECK(readers, ==, 0);
+ TRACK(writers, dec);
+ TRACK(readers, inc);
+
+ downgrade_write(&rwsem);
+
+ ACCOUNT(downgrades, N);
+}
+
+static inline void sched(void)
+{
+ if (do_sched)
+ schedule();
+}
+
+static int spinlocker(void *arg)
+{
+ unsigned int N = (unsigned long) arg;
+
+ set_user_nice(current, 19);
+
+ while (atomic_read(&do_stuff)) {
+ do_spin_lock(N);
+ if (load)
+ udelay(load);
+ do_spin_unlock(N);
+ sched();
+ if (interval)
+ udelay(interval);
+ }
+
+ if (verbose >= 2)
+ printk("%s: done\n", current->comm);
+ complete_and_exit(&sp_comp[N], 0);
+}
+
+static int mutexer(void *arg)
+{
+ unsigned int N = (unsigned long) arg;
+
+ set_user_nice(current, 19);
+
+ while (atomic_read(&do_stuff)) {
+ do_mutex_lock(N);
+ if (load)
+ udelay(load);
+ do_mutex_unlock(N);
+ sched();
+ if (interval)
+ udelay(interval);
+ }
+
+ if (verbose >= 2)
+ printk("%s: done\n", current->comm);
+ complete_and_exit(&mx_comp[N], 0);
+}
+
+static int semaphorer(void *arg)
+{
+ unsigned int N = (unsigned long) arg;
+
+ set_user_nice(current, 19);
+
+ while (atomic_read(&do_stuff)) {
+ do_down(N);
+ if (load)
+ udelay(load);
+ do_up(N);
+ sched();
+ if (interval)
+ udelay(interval);
+ }
+
+ if (verbose >= 2)
+ printk("%s: done\n", current->comm);
+ complete_and_exit(&sm_comp[N], 0);
+}
+
+static int reader(void *arg)
+{
+ unsigned int N = (unsigned long) arg;
+
+ set_user_nice(current, 19);
+
+ while (atomic_read(&do_stuff)) {
+ do_down_read(N);
+#ifdef LOAD_TEST
+ if (load)
+ udelay(load);
+#endif
+ do_up_read(N);
+ sched();
+ if (interval)
+ udelay(interval);
+ }
+
+ if (verbose >= 2)
+ printk("%s: done\n", current->comm);
+ complete_and_exit(&rd_comp[N], 0);
+}
+
+static int writer(void *arg)
+{
+ unsigned int N = (unsigned long) arg;
+
+ set_user_nice(current, 19);
+
+ while (atomic_read(&do_stuff)) {
+ do_down_write(N);
+#ifdef LOAD_TEST
+ if (load)
+ udelay(load);
+#endif
+ do_up_write(N);
+ sched();
+ if (interval)
+ udelay(interval);
+ }
+
+ if (verbose >= 2)
+ printk("%s: done\n", current->comm);
+ complete_and_exit(&wr_comp[N], 0);
+}
+
+static int downgrader(void *arg)
+{
+ unsigned int N = (unsigned long) arg;
+
+ set_user_nice(current, 19);
+
+ while (atomic_read(&do_stuff)) {
+ do_down_write(N);
+#ifdef LOAD_TEST
+ if (load)
+ udelay(load);
+#endif
+ do_downgrade_write(N);
+#ifdef LOAD_TEST
+ if (load)
+ udelay(load);
+#endif
+ do_up_read(N);
+ sched();
+ if (interval)
+ udelay(interval);
+ }
+
+ if (verbose >= 2)
+ printk("%s: done\n", current->comm);
+ complete_and_exit(&dg_comp[N], 0);
+}
+
+static void stop_test(struct timer_list *t)
+{
+ atomic_set(&do_stuff, 0);
+}
+
+static unsigned int total(const char *what, unsigned int counts[], int num)
+{
+ unsigned int tot = 0, max = 0, min = UINT_MAX, zeros = 0, cnt;
+ int loop;
+
+ for (loop = 0; loop < num; loop++) {
+ cnt = counts[loop];
+
+ if (cnt == 0) {
+ zeros++;
+ min = 0;
+ continue;
+ }
+
+ tot += cnt;
+ if (tot > max)
+ max = tot;
+ if (tot < min)
+ min = tot;
+ }
+
+ if (verbose && tot > 0) {
+ printk("%s:", what);
+
+ for (loop = 0; loop < num; loop++) {
+ cnt = counts[loop];
+
+ if (cnt == 0)
+ printk(" zzz");
+ else
+ printk(" %d%%", cnt * 100 / tot);
+ }
+
+ printk("\n");
+ }
+
+ return tot;
+}
+
+/*****************************************************************************/
+/*
+ *
+ */
+static int __init do_tests(void)
+{
+ unsigned long loop;
+ unsigned int spinlock_total, mutex_total, sem_total;
+ unsigned int rd_total, wr_total, dg_total;
+
+ if (numsp < 0 || numsp > MAX_THREADS ||
+ nummx < 0 || nummx > MAX_THREADS ||
+ numsm < 0 || numsm > MAX_THREADS ||
+ numrd < 0 || numrd > MAX_THREADS ||
+ numwr < 0 || numwr > MAX_THREADS ||
+ numdg < 0 || numdg > MAX_THREADS ||
+ seminit < 1 ||
+ elapse < 1 ||
+ load < 0 || load > 999 ||
+ interval < 0 || interval > 999
+ ) {
+ printk("Parameter out of range\n");
+ return -ERANGE;
+ }
+
+ if ((numsp | nummx | numsm | numrd | numwr | numdg) == 0) {
+ int num = num_online_cpus();
+
+ if (num > MAX_THREADS)
+ num = MAX_THREADS;
+ numsp = nummx = numsm = numrd = numwr = numdg = num;
+
+ load = 1;
+ interval = 1;
+ do_sched = 1;
+ printk("No parameters - using defaults.\n");
+ }
+
+ if (verbose)
+ printk("\nStarting synchronisation primitive tests...\n");
+
+ spin_lock_init(&spinlock);
+ mutex_init(&mutex);
+ sema_init(&sem, seminit);
+ init_rwsem(&rwsem);
+ atomic_set(&do_stuff, 1);
+
+ /* kick off all the children */
+ for (loop = 0; loop < MAX_THREADS; loop++) {
+ if (loop < numsp) {
+ init_completion(&sp_comp[loop]);
+ kthread_run(spinlocker, (void *) loop,
+ "Spinlock%lu", loop);
+ }
+
+ if (loop < nummx) {
+ init_completion(&mx_comp[loop]);
+ kthread_run(mutexer, (void *) loop, "Mutex%lu", loop);
+ }
+
+ if (loop < numsm) {
+ init_completion(&sm_comp[loop]);
+ kthread_run(semaphorer, (void *) loop, "Sem%lu", loop);
+ }
+
+ if (loop < numrd) {
+ init_completion(&rd_comp[loop]);
+ kthread_run(reader, (void *) loop, "Read%lu", loop);
+ }
+
+ if (loop < numwr) {
+ init_completion(&wr_comp[loop]);
+ kthread_run(writer, (void *) loop, "Write%lu", loop);
+ }
+
+ if (loop < numdg) {
+ init_completion(&dg_comp[loop]);
+ kthread_run(downgrader, (void *) loop, "Down%lu", loop);
+ }
+ }
+
+ /* set a stop timer */
+ timer_setup(&timer, stop_test, 0);
+ timer.expires = jiffies + elapse * HZ;
+ add_timer(&timer);
+
+ /* now wait until it's all done */
+ for (loop = 0; loop < numsp; loop++)
+ wait_for_completion(&sp_comp[loop]);
+
+ for (loop = 0; loop < nummx; loop++)
+ wait_for_completion(&mx_comp[loop]);
+
+ for (loop = 0; loop < numsm; loop++)
+ wait_for_completion(&sm_comp[loop]);
+
+ for (loop = 0; loop < numrd; loop++)
+ wait_for_completion(&rd_comp[loop]);
+
+ for (loop = 0; loop < numwr; loop++)
+ wait_for_completion(&wr_comp[loop]);
+
+ for (loop = 0; loop < numdg; loop++)
+ wait_for_completion(&dg_comp[loop]);
+
+ atomic_set(&do_stuff, 0);
+ del_timer(&timer);
+
+ if (spin_is_locked(&spinlock))
+ printk(KERN_ERR "Spinlock is still locked!\n");
+
+ if (mutex_is_locked(&mutex))
+ printk(KERN_ERR "Mutex is still locked!\n");
+
+ /* count up */
+ spinlock_total = total("SP ", spinlocks_taken, numsp);
+ mutex_total = total("MTX", mutexes_taken, nummx);
+ sem_total = total("SEM", semaphores_taken, numsm);
+ rd_total = total("RD ", reads_taken, numrd);
+ wr_total = total("WR ", writes_taken, numwr);
+ dg_total = total("DG ", downgrades_taken, numdg);
+
+ /* print the results */
+ if (verbose) {
+ printk("spinlocks taken: %u\n", spinlock_total);
+ printk("mutexes taken: %u\n", mutex_total);
+ printk("semaphores taken: %u\n", sem_total);
+ printk("reads taken: %u\n", rd_total);
+ printk("writes taken: %u\n", wr_total);
+ printk("downgrades taken: %u\n", dg_total);
+ }
+ else {
+ char buf[30];
+
+ sprintf(buf, "%d/%d", interval, load);
+
+ printk("%3d %3d %3d %3d %3d %3d %c %5s %9u %9u %9u %9u %9u %9u\n",
+ numsp, nummx, numsm, numrd, numwr, numdg,
+ do_sched ? 's' : '-',
+ buf,
+ spinlock_total,
+ mutex_total,
+ sem_total,
+ rd_total,
+ wr_total,
+ dg_total);
+ }
+
+ /* tell insmod to discard the module */
+ if (verbose)
+ printk("Tests complete\n");
+ return -ENOANO;
+
+} /* end do_tests() */
+
+module_init(do_tests);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e80a745a11e2..62ccf6b10584 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -76,6 +76,20 @@ config MESSAGE_LOGLEVEL_DEFAULT
by default. To change that, use loglevel=<x> in the kernel bootargs,
or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
+config DEBUG_SYNCHRO_TEST
+ tristate "Synchronisation primitive testing module"
+ depends on DEBUG_KERNEL
+ default n
+ help
+ This option provides a kernel module that can thrash the sleepable
+ synchronisation primitives (mutexes and semaphores).
+
+ You should say N or M here. Whilst the module can be built in, it's
+ not recommended as it requires module parameters supplying to get it
+ to do anything.
+
+ See Documentation/synchro-test.txt.
+
config BOOT_PRINTK_DELAY
bool "Delay each boot printk message by N milliseconds"
depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY