diff options
| -rw-r--r-- | Documentation/RCU/torture.txt | 9 | ||||
| -rw-r--r-- | kernel/rcutorture.c | 109 |
2 files changed, 113 insertions, 5 deletions
diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt index 2174badd31e0..2180ef93accc 100644 --- a/Documentation/RCU/torture.txt +++ b/Documentation/RCU/torture.txt @@ -28,6 +28,15 @@ nreaders This is the number of RCU reading threads supported. To properly exercise RCU implementations with preemptible read-side critical sections. +nfakewriters This is the number of RCU fake writer threads to run. Fake + writer threads repeatedly use the synchronous "wait for + current readers" function of the interface selected by + torture_type, with a delay between calls to allow for various + different numbers of writers running in parallel. + nfakewriters defaults to 4, which provides enough parallelism + to trigger special cases caused by multiple writers, such as + the synchronize_srcu() early return optimization. + stat_interval The number of seconds between output of torture statistics (via printk()). Regardless of the interval, statistics are printed when the module is unloaded. diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 43d6d4f9ef09..e0450210ce4d 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -15,9 +15,10 @@ * 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) IBM Corporation, 2005 + * Copyright (C) IBM Corporation, 2005, 2006 * * Authors: Paul E. McKenney <paulmck@us.ibm.com> + * Josh Triplett <josh@freedesktop.org> * * See also: Documentation/RCU/torture.txt */ @@ -47,9 +48,11 @@ #include <linux/srcu.h> MODULE_LICENSE("GPL"); -MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>"); +MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and " + "Josh Triplett <josh@freedesktop.org>"); static int nreaders = -1; /* # reader threads, defaults to 2*ncpus */ +static int nfakewriters = 4; /* # fake writer threads */ static int stat_interval; /* Interval between stats, in seconds. */ /* Defaults to "only at end of test". */ static int verbose; /* Print more debug info. */ @@ -59,6 +62,8 @@ static char *torture_type = "rcu"; /* What to torture: rcu, rcu_bh, srcu. */ module_param(nreaders, int, 0); MODULE_PARM_DESC(nreaders, "Number of RCU reader threads"); +module_param(nfakewriters, int, 0); +MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads"); module_param(stat_interval, int, 0); MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s"); module_param(verbose, bool, 0); @@ -82,6 +87,7 @@ static char printk_buf[4096]; static int nrealreaders; static struct task_struct *writer_task; +static struct task_struct **fakewriter_tasks; static struct task_struct **reader_tasks; static struct task_struct *stats_task; static struct task_struct *shuffler_task; @@ -186,6 +192,7 @@ struct rcu_torture_ops { void (*readunlock)(int idx); int (*completed)(void); void (*deferredfree)(struct rcu_torture *p); + void (*sync)(void); int (*stats)(char *page); char *name; }; @@ -258,6 +265,7 @@ static struct rcu_torture_ops rcu_ops = { .readunlock = rcu_torture_read_unlock, .completed = rcu_torture_completed, .deferredfree = rcu_torture_deferred_free, + .sync = synchronize_rcu, .stats = NULL, .name = "rcu" }; @@ -287,6 +295,28 @@ static void rcu_bh_torture_deferred_free(struct rcu_torture *p) call_rcu_bh(&p->rtort_rcu, rcu_torture_cb); } +struct rcu_bh_torture_synchronize { + struct rcu_head head; + struct completion completion; +}; + +static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head) +{ + struct rcu_bh_torture_synchronize *rcu; + + rcu = container_of(head, struct rcu_bh_torture_synchronize, head); + complete(&rcu->completion); +} + +static void rcu_bh_torture_synchronize(void) +{ + struct rcu_bh_torture_synchronize rcu; + + init_completion(&rcu.completion); + call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb); + wait_for_completion(&rcu.completion); +} + static struct rcu_torture_ops rcu_bh_ops = { .init = NULL, .cleanup = NULL, @@ -295,6 +325,7 @@ static struct rcu_torture_ops rcu_bh_ops = { .readunlock = rcu_bh_torture_read_unlock, .completed = rcu_bh_torture_completed, .deferredfree = rcu_bh_torture_deferred_free, + .sync = rcu_bh_torture_synchronize, .stats = NULL, .name = "rcu_bh" }; @@ -367,6 +398,11 @@ static void srcu_torture_deferred_free(struct rcu_torture *p) } } +static void srcu_torture_synchronize(void) +{ + synchronize_srcu(&srcu_ctl); +} + static int srcu_torture_stats(char *page) { int cnt = 0; @@ -392,6 +428,7 @@ static struct rcu_torture_ops srcu_ops = { .readunlock = srcu_torture_read_unlock, .completed = srcu_torture_completed, .deferredfree = srcu_torture_deferred_free, + .sync = srcu_torture_synchronize, .stats = srcu_torture_stats, .name = "srcu" }; @@ -444,6 +481,30 @@ rcu_torture_writer(void *arg) } /* + * RCU torture fake writer kthread. Repeatedly calls sync, with a random + * delay between calls. + */ +static int +rcu_torture_fakewriter(void *arg) +{ + DEFINE_RCU_RANDOM(rand); + + VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started"); + set_user_nice(current, 19); + + do { + schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10); + udelay(rcu_random(&rand) & 0x3ff); + cur_ops->sync(); + } while (!kthread_should_stop() && !fullstop); + + VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping"); + while (!kthread_should_stop()) + schedule_timeout_uninterruptible(1); + return 0; +} + +/* * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current, * incrementing the corresponding element of the pipeline array. The * counter in the element should never be greater than 1, otherwise, the @@ -621,6 +682,12 @@ static void rcu_torture_shuffle_tasks(void) set_cpus_allowed(reader_tasks[i], tmp_mask); } + if (fakewriter_tasks != NULL) { + for (i = 0; i < nfakewriters; i++) + if (fakewriter_tasks[i]) + set_cpus_allowed(fakewriter_tasks[i], tmp_mask); + } + if (writer_task) set_cpus_allowed(writer_task, tmp_mask); @@ -654,11 +721,12 @@ rcu_torture_shuffle(void *arg) static inline void rcu_torture_print_module_parms(char *tag) { - printk(KERN_ALERT "%s" TORTURE_FLAG "--- %s: nreaders=%d " + printk(KERN_ALERT "%s" TORTURE_FLAG + "--- %s: nreaders=%d nfakewriters=%d " "stat_interval=%d verbose=%d test_no_idle_hz=%d " "shuffle_interval = %d\n", - torture_type, tag, nrealreaders, stat_interval, verbose, - test_no_idle_hz, shuffle_interval); + torture_type, tag, nrealreaders, nfakewriters, + stat_interval, verbose, test_no_idle_hz, shuffle_interval); } static void @@ -693,6 +761,19 @@ rcu_torture_cleanup(void) } rcu_torture_current = NULL; + if (fakewriter_tasks != NULL) { + for (i = 0; i < nfakewriters; i++) { + if (fakewriter_tasks[i] != NULL) { + VERBOSE_PRINTK_STRING( + "Stopping rcu_torture_fakewriter task"); + kthread_stop(fakewriter_tasks[i]); + } + fakewriter_tasks[i] = NULL; + } + kfree(fakewriter_tasks); + fakewriter_tasks = NULL; + } + if (stats_task != NULL) { VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task"); kthread_stop(stats_task); @@ -780,6 +861,24 @@ rcu_torture_init(void) writer_task = NULL; goto unwind; } + fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]), + GFP_KERNEL); + if (fakewriter_tasks == NULL) { + VERBOSE_PRINTK_ERRSTRING("out of memory"); + firsterr = -ENOMEM; + goto unwind; + } + for (i = 0; i < nfakewriters; i++) { + VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task"); + fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL, + "rcu_torture_fakewriter"); + if (IS_ERR(fakewriter_tasks[i])) { + firsterr = PTR_ERR(fakewriter_tasks[i]); + VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter"); + fakewriter_tasks[i] = NULL; + goto unwind; + } + } reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]), GFP_KERNEL); if (reader_tasks == NULL) { |