| 1 | /* test-fair-rwlock.c |
| 2 | * |
| 3 | */ |
| 4 | |
| 5 | #include <linux/module.h> |
| 6 | #include <linux/proc_fs.h> |
| 7 | #include <linux/sched.h> |
| 8 | #include <linux/timex.h> |
| 9 | #include <linux/fair-rwlock.h> |
| 10 | #include <linux/kthread.h> |
| 11 | #include <linux/delay.h> |
| 12 | #include <linux/hardirq.h> |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/percpu.h> |
| 15 | #include <asm/ptrace.h> |
| 16 | |
| 17 | #if (NR_CPUS > 64 && (BITS_PER_LONG == 32 || NR_CPUS > 32768)) |
| 18 | #error "fair rwlock needs more bits per long to deal with that many CPUs" |
| 19 | #endif |
| 20 | |
| 21 | #define THREAD_ROFFSET 1UL |
| 22 | #define THREAD_RMASK ((NR_CPUS - 1) * THREAD_ROFFSET) |
| 23 | #define SOFTIRQ_ROFFSET (THREAD_RMASK + 1) |
| 24 | #define SOFTIRQ_RMASK ((NR_CPUS - 1) * SOFTIRQ_ROFFSET) |
| 25 | #define HARDIRQ_ROFFSET ((SOFTIRQ_RMASK | THREAD_RMASK) + 1) |
| 26 | #define HARDIRQ_RMASK ((NR_CPUS - 1) * HARDIRQ_ROFFSET) |
| 27 | |
| 28 | #define SUBSCRIBERS_WOFFSET \ |
| 29 | ((HARDIRQ_RMASK | SOFTIRQ_RMASK | THREAD_RMASK) + 1) |
| 30 | #define SUBSCRIBERS_WMASK \ |
| 31 | ((NR_CPUS - 1) * SUBSCRIBERS_WOFFSET) |
| 32 | #define WRITER_MUTEX \ |
| 33 | ((SUBSCRIBERS_WMASK | HARDIRQ_RMASK | SOFTIRQ_RMASK | THREAD_RMASK) + 1) |
| 34 | #define SOFTIRQ_WMASK (WRITER_MUTEX << 1) |
| 35 | #define SOFTIRQ_WOFFSET SOFTIRQ_WMASK |
| 36 | #define HARDIRQ_WMASK (SOFTIRQ_WMASK << 1) |
| 37 | #define HARDIRQ_WOFFSET HARDIRQ_WMASK |
| 38 | |
| 39 | #define NR_VARS 100 |
| 40 | #define NR_WRITERS 3 |
| 41 | #define NR_READERS 6 |
| 42 | #define NR_INTERRUPT_READERS 2 |
| 43 | |
| 44 | static int var[NR_VARS]; |
| 45 | static struct task_struct *reader_threads[NR_READERS]; |
| 46 | static struct task_struct *writer_threads[NR_WRITERS]; |
| 47 | static struct task_struct *interrupt_reader; |
| 48 | |
| 49 | static struct fair_rwlock frwlock = { |
| 50 | .value = ATOMIC_LONG_INIT(0), |
| 51 | }; |
| 52 | |
| 53 | struct proc_dir_entry *pentry = NULL; |
| 54 | |
| 55 | static int reader_thread(void *data) |
| 56 | { |
| 57 | int i; |
| 58 | int prev, cur; |
| 59 | unsigned long iter = 0; |
| 60 | cycles_t time1, time2, delaymax = 0; |
| 61 | |
| 62 | printk("reader_thread/%lu runnning\n", (unsigned long)data); |
| 63 | do { |
| 64 | iter++; |
| 65 | preempt_disable(); /* for get_cycles accuracy */ |
| 66 | time1 = get_cycles(); |
| 67 | fair_read_lock(&frwlock); |
| 68 | time2 = get_cycles(); |
| 69 | delaymax = max(delaymax, time2 - time1); |
| 70 | prev = var[0]; |
| 71 | for (i = 1; i < NR_VARS; i++) { |
| 72 | cur = var[i]; |
| 73 | if (cur != prev) |
| 74 | printk(KERN_ALERT |
| 75 | "Unequal cur %d/prev %d at i %d, iter %lu " |
| 76 | "in thread\n", cur, prev, i, iter); |
| 77 | } |
| 78 | fair_read_unlock(&frwlock); |
| 79 | preempt_enable(); /* for get_cycles accuracy */ |
| 80 | //msleep(100); |
| 81 | } while (!kthread_should_stop()); |
| 82 | printk("reader_thread/%lu iterations : %lu, " |
| 83 | "max contention %llu cycles\n", |
| 84 | (unsigned long)data, iter, delaymax); |
| 85 | return 0; |
| 86 | } |
| 87 | |
| 88 | DEFINE_PER_CPU(cycles_t, int_delaymax); |
| 89 | |
| 90 | static void interrupt_reader_ipi(void *data) |
| 91 | { |
| 92 | int i; |
| 93 | int prev, cur; |
| 94 | cycles_t time1, time2; |
| 95 | cycles_t *delaymax; |
| 96 | |
| 97 | /* |
| 98 | * Skip the ipi caller, not in irq context. |
| 99 | */ |
| 100 | if (!in_irq()) |
| 101 | return; |
| 102 | |
| 103 | delaymax = &per_cpu(int_delaymax, smp_processor_id()); |
| 104 | time1 = get_cycles(); |
| 105 | fair_read_lock(&frwlock); |
| 106 | time2 = get_cycles(); |
| 107 | *delaymax = max(*delaymax, time2 - time1); |
| 108 | prev = var[0]; |
| 109 | for (i = 1; i < NR_VARS; i++) { |
| 110 | cur = var[i]; |
| 111 | if (cur != prev) |
| 112 | printk(KERN_ALERT |
| 113 | "Unequal cur %d/prev %d at i %d in interrupt\n", |
| 114 | cur, prev, i); |
| 115 | } |
| 116 | fair_read_unlock(&frwlock); |
| 117 | } |
| 118 | |
| 119 | static int interrupt_reader_thread(void *data) |
| 120 | { |
| 121 | unsigned long iter = 0; |
| 122 | int i; |
| 123 | |
| 124 | do { |
| 125 | iter++; |
| 126 | on_each_cpu(interrupt_reader_ipi, NULL, 0); |
| 127 | msleep(100); |
| 128 | } while (!kthread_should_stop()); |
| 129 | printk("interrupt_reader_thread/%lu iterations : %lu\n", |
| 130 | (unsigned long)data, iter); |
| 131 | for_each_online_cpu(i) { |
| 132 | printk("interrupt readers on CPU %i, " |
| 133 | "max contention : %llu cycles\n", |
| 134 | i, per_cpu(int_delaymax, i)); |
| 135 | } |
| 136 | return 0; |
| 137 | } |
| 138 | |
| 139 | static int writer_thread(void *data) |
| 140 | { |
| 141 | int i; |
| 142 | int new; |
| 143 | unsigned long iter = 0; |
| 144 | cycles_t time1, time2, delaymax = 0; |
| 145 | |
| 146 | printk("writer_thread/%lu runnning\n", (unsigned long)data); |
| 147 | do { |
| 148 | iter++; |
| 149 | preempt_disable(); /* for get_cycles accuracy */ |
| 150 | time1 = get_cycles(); |
| 151 | fair_write_lock_irq(&frwlock); |
| 152 | //fair_write_lock(&frwlock); |
| 153 | time2 = get_cycles(); |
| 154 | delaymax = max(delaymax, time2 - time1); |
| 155 | new = (int)get_cycles(); |
| 156 | for (i = 0; i < NR_VARS; i++) { |
| 157 | var[i] = new; |
| 158 | } |
| 159 | //fair_write_unlock(&frwlock); |
| 160 | fair_write_unlock_irq(&frwlock); |
| 161 | preempt_enable(); /* for get_cycles accuracy */ |
| 162 | //msleep(100); |
| 163 | } while (!kthread_should_stop()); |
| 164 | printk("writer_thread/%lu iterations : %lu, " |
| 165 | "max contention %llu cycles\n", |
| 166 | (unsigned long)data, iter, delaymax); |
| 167 | return 0; |
| 168 | } |
| 169 | |
| 170 | static void fair_rwlock_create(void) |
| 171 | { |
| 172 | unsigned long i; |
| 173 | |
| 174 | for (i = 0; i < NR_READERS; i++) { |
| 175 | printk("starting reader thread %lu\n", i); |
| 176 | reader_threads[i] = kthread_run(reader_thread, (void *)i, |
| 177 | "frwlock_reader"); |
| 178 | BUG_ON(!reader_threads[i]); |
| 179 | } |
| 180 | |
| 181 | printk("starting interrupt reader %lu\n", i); |
| 182 | interrupt_reader = kthread_run(interrupt_reader_thread, NULL, |
| 183 | "frwlock_interrupt_reader"); |
| 184 | |
| 185 | for (i = 0; i < NR_WRITERS; i++) { |
| 186 | printk("starting writer thread %lu\n", i); |
| 187 | writer_threads[i] = kthread_run(writer_thread, (void *)i, |
| 188 | "frwlock_writer"); |
| 189 | BUG_ON(!writer_threads[i]); |
| 190 | } |
| 191 | } |
| 192 | |
| 193 | static void fair_rwlock_stop(void) |
| 194 | { |
| 195 | unsigned long i; |
| 196 | |
| 197 | for (i = 0; i < NR_WRITERS; i++) { |
| 198 | kthread_stop(writer_threads[i]); |
| 199 | } |
| 200 | |
| 201 | for (i = 0; i < NR_READERS; i++) { |
| 202 | kthread_stop(reader_threads[i]); |
| 203 | } |
| 204 | |
| 205 | kthread_stop(interrupt_reader); |
| 206 | } |
| 207 | |
| 208 | |
| 209 | static void perform_test(const char *name, void (*callback)(void)) |
| 210 | { |
| 211 | printk("%s\n", name); |
| 212 | callback(); |
| 213 | } |
| 214 | |
| 215 | static int my_open(struct inode *inode, struct file *file) |
| 216 | { |
| 217 | perform_test("fair-rwlock-create", fair_rwlock_create); |
| 218 | ssleep(30); |
| 219 | perform_test("fair-rwlock-stop", fair_rwlock_stop); |
| 220 | |
| 221 | return -EPERM; |
| 222 | } |
| 223 | |
| 224 | |
| 225 | static struct file_operations my_operations = { |
| 226 | .open = my_open, |
| 227 | }; |
| 228 | |
| 229 | int init_module(void) |
| 230 | { |
| 231 | pentry = create_proc_entry("testfrwlock", 0444, NULL); |
| 232 | if (pentry) |
| 233 | pentry->proc_fops = &my_operations; |
| 234 | |
| 235 | printk("NR_CPUS : %d\n", NR_CPUS); |
| 236 | printk("THREAD_ROFFSET : %lX\n", THREAD_ROFFSET); |
| 237 | printk("THREAD_RMASK : %lX\n", THREAD_RMASK); |
| 238 | printk("SOFTIRQ_ROFFSET : %lX\n", SOFTIRQ_ROFFSET); |
| 239 | printk("SOFTIRQ_RMASK : %lX\n", SOFTIRQ_RMASK); |
| 240 | printk("HARDIRQ_ROFFSET : %lX\n", HARDIRQ_ROFFSET); |
| 241 | printk("HARDIRQ_RMASK : %lX\n", HARDIRQ_RMASK); |
| 242 | printk("SUBSCRIBERS_WOFFSET : %lX\n", SUBSCRIBERS_WOFFSET); |
| 243 | printk("SUBSCRIBERS_WMASK : %lX\n", SUBSCRIBERS_WMASK); |
| 244 | printk("WRITER_MUTEX : %lX\n", WRITER_MUTEX); |
| 245 | printk("SOFTIRQ_WMASK : %lX\n", SOFTIRQ_WMASK); |
| 246 | printk("HARDIRQ_WMASK : %lX\n", HARDIRQ_WMASK); |
| 247 | |
| 248 | return 0; |
| 249 | } |
| 250 | |
| 251 | void cleanup_module(void) |
| 252 | { |
| 253 | remove_proc_entry("testfrwlock", NULL); |
| 254 | } |
| 255 | |
| 256 | MODULE_LICENSE("GPL"); |
| 257 | MODULE_AUTHOR("Mathieu Desnoyers"); |
| 258 | MODULE_DESCRIPTION("Fair rwlock test"); |