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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> |
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14 | #include <linux/percpu.h> |
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15 | #include <asm/ptrace.h> |
16 | |
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17 | #if (NR_CPUS > 64 && (BITS_PER_LONG == 32 || NR_CPUS > 32768)) |
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18 | #error "fair rwlock needs more bits per long to deal with that many CPUs" |
19 | #endif |
20 | |
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21 | /* Test duration, in seconds */ |
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22 | #define TEST_DURATION 60 |
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23 | |
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24 | #define THREAD_ROFFSET 1UL |
25 | #define THREAD_RMASK ((NR_CPUS - 1) * THREAD_ROFFSET) |
26 | #define SOFTIRQ_ROFFSET (THREAD_RMASK + 1) |
27 | #define SOFTIRQ_RMASK ((NR_CPUS - 1) * SOFTIRQ_ROFFSET) |
28 | #define HARDIRQ_ROFFSET ((SOFTIRQ_RMASK | THREAD_RMASK) + 1) |
29 | #define HARDIRQ_RMASK ((NR_CPUS - 1) * HARDIRQ_ROFFSET) |
30 | |
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31 | #define SUBSCRIBERS_WOFFSET \ |
32 | ((HARDIRQ_RMASK | SOFTIRQ_RMASK | THREAD_RMASK) + 1) |
33 | #define SUBSCRIBERS_WMASK \ |
34 | ((NR_CPUS - 1) * SUBSCRIBERS_WOFFSET) |
35 | #define WRITER_MUTEX \ |
36 | ((SUBSCRIBERS_WMASK | HARDIRQ_RMASK | SOFTIRQ_RMASK | THREAD_RMASK) + 1) |
37 | #define SOFTIRQ_WMASK (WRITER_MUTEX << 1) |
38 | #define SOFTIRQ_WOFFSET SOFTIRQ_WMASK |
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39 | #define HARDIRQ_WMASK (SOFTIRQ_WMASK << 1) |
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40 | #define HARDIRQ_WOFFSET HARDIRQ_WMASK |
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41 | |
42 | #define NR_VARS 100 |
43 | #define NR_WRITERS 3 |
44 | #define NR_READERS 6 |
45 | #define NR_INTERRUPT_READERS 2 |
46 | |
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47 | /* Writer iteration delay, in ms. 0 for busy loop. */ |
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48 | #define WRITER_DELAY 0 |
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49 | |
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50 | static int var[NR_VARS]; |
51 | static struct task_struct *reader_threads[NR_READERS]; |
52 | static struct task_struct *writer_threads[NR_WRITERS]; |
53 | static struct task_struct *interrupt_reader; |
54 | |
55 | static struct fair_rwlock frwlock = { |
56 | .value = ATOMIC_LONG_INIT(0), |
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57 | }; |
58 | |
59 | struct proc_dir_entry *pentry = NULL; |
60 | |
61 | static int reader_thread(void *data) |
62 | { |
63 | int i; |
64 | int prev, cur; |
65 | unsigned long iter = 0; |
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66 | cycles_t time1, time2, delaymax = 0; |
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67 | |
68 | printk("reader_thread/%lu runnning\n", (unsigned long)data); |
69 | do { |
70 | iter++; |
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71 | preempt_disable(); /* for get_cycles accuracy */ |
72 | time1 = get_cycles(); |
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73 | fair_read_lock(&frwlock); |
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74 | time2 = get_cycles(); |
75 | delaymax = max(delaymax, time2 - time1); |
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76 | prev = var[0]; |
77 | for (i = 1; i < NR_VARS; i++) { |
78 | cur = var[i]; |
79 | if (cur != prev) |
80 | printk(KERN_ALERT |
81 | "Unequal cur %d/prev %d at i %d, iter %lu " |
82 | "in thread\n", cur, prev, i, iter); |
83 | } |
84 | fair_read_unlock(&frwlock); |
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85 | preempt_enable(); /* for get_cycles accuracy */ |
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86 | //msleep(100); |
87 | } while (!kthread_should_stop()); |
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88 | printk("reader_thread/%lu iterations : %lu, " |
89 | "max contention %llu cycles\n", |
90 | (unsigned long)data, iter, delaymax); |
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91 | return 0; |
92 | } |
93 | |
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94 | DEFINE_PER_CPU(cycles_t, int_delaymax); |
95 | |
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96 | static void interrupt_reader_ipi(void *data) |
97 | { |
98 | int i; |
99 | int prev, cur; |
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100 | cycles_t time1, time2; |
101 | cycles_t *delaymax; |
102 | |
103 | /* |
104 | * Skip the ipi caller, not in irq context. |
105 | */ |
106 | if (!in_irq()) |
107 | return; |
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108 | |
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109 | delaymax = &per_cpu(int_delaymax, smp_processor_id()); |
110 | time1 = get_cycles(); |
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111 | fair_read_lock(&frwlock); |
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112 | time2 = get_cycles(); |
113 | *delaymax = max(*delaymax, time2 - time1); |
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114 | prev = var[0]; |
115 | for (i = 1; i < NR_VARS; i++) { |
116 | cur = var[i]; |
117 | if (cur != prev) |
118 | printk(KERN_ALERT |
119 | "Unequal cur %d/prev %d at i %d in interrupt\n", |
120 | cur, prev, i); |
121 | } |
122 | fair_read_unlock(&frwlock); |
123 | } |
124 | |
125 | static int interrupt_reader_thread(void *data) |
126 | { |
127 | unsigned long iter = 0; |
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128 | int i; |
129 | |
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130 | do { |
131 | iter++; |
132 | on_each_cpu(interrupt_reader_ipi, NULL, 0); |
133 | msleep(100); |
134 | } while (!kthread_should_stop()); |
135 | printk("interrupt_reader_thread/%lu iterations : %lu\n", |
136 | (unsigned long)data, iter); |
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137 | for_each_online_cpu(i) { |
138 | printk("interrupt readers on CPU %i, " |
139 | "max contention : %llu cycles\n", |
140 | i, per_cpu(int_delaymax, i)); |
141 | } |
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142 | return 0; |
143 | } |
144 | |
145 | static int writer_thread(void *data) |
146 | { |
147 | int i; |
148 | int new; |
149 | unsigned long iter = 0; |
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150 | cycles_t time1, time2, delaymax = 0; |
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151 | |
152 | printk("writer_thread/%lu runnning\n", (unsigned long)data); |
153 | do { |
154 | iter++; |
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155 | preempt_disable(); /* for get_cycles accuracy */ |
156 | time1 = get_cycles(); |
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157 | fair_write_lock_irq(&frwlock); |
158 | //fair_write_lock(&frwlock); |
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159 | time2 = get_cycles(); |
160 | delaymax = max(delaymax, time2 - time1); |
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161 | new = (int)get_cycles(); |
162 | for (i = 0; i < NR_VARS; i++) { |
163 | var[i] = new; |
164 | } |
165 | //fair_write_unlock(&frwlock); |
166 | fair_write_unlock_irq(&frwlock); |
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167 | preempt_enable(); /* for get_cycles accuracy */ |
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168 | if (WRITER_DELAY > 0) |
169 | msleep(WRITER_DELAY); |
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170 | } while (!kthread_should_stop()); |
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171 | printk("writer_thread/%lu iterations : %lu, " |
172 | "max contention %llu cycles\n", |
173 | (unsigned long)data, iter, delaymax); |
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174 | return 0; |
175 | } |
176 | |
177 | static void fair_rwlock_create(void) |
178 | { |
179 | unsigned long i; |
180 | |
181 | for (i = 0; i < NR_READERS; i++) { |
182 | printk("starting reader thread %lu\n", i); |
183 | reader_threads[i] = kthread_run(reader_thread, (void *)i, |
184 | "frwlock_reader"); |
185 | BUG_ON(!reader_threads[i]); |
186 | } |
187 | |
188 | printk("starting interrupt reader %lu\n", i); |
189 | interrupt_reader = kthread_run(interrupt_reader_thread, NULL, |
190 | "frwlock_interrupt_reader"); |
191 | |
192 | for (i = 0; i < NR_WRITERS; i++) { |
193 | printk("starting writer thread %lu\n", i); |
194 | writer_threads[i] = kthread_run(writer_thread, (void *)i, |
195 | "frwlock_writer"); |
196 | BUG_ON(!writer_threads[i]); |
197 | } |
198 | } |
199 | |
200 | static void fair_rwlock_stop(void) |
201 | { |
202 | unsigned long i; |
203 | |
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204 | for (i = 0; i < NR_WRITERS; i++) { |
205 | kthread_stop(writer_threads[i]); |
206 | } |
207 | |
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208 | for (i = 0; i < NR_READERS; i++) { |
209 | kthread_stop(reader_threads[i]); |
210 | } |
211 | |
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212 | kthread_stop(interrupt_reader); |
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213 | } |
214 | |
215 | |
216 | static void perform_test(const char *name, void (*callback)(void)) |
217 | { |
218 | printk("%s\n", name); |
219 | callback(); |
220 | } |
221 | |
222 | static int my_open(struct inode *inode, struct file *file) |
223 | { |
224 | perform_test("fair-rwlock-create", fair_rwlock_create); |
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225 | ssleep(TEST_DURATION); |
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226 | perform_test("fair-rwlock-stop", fair_rwlock_stop); |
227 | |
228 | return -EPERM; |
229 | } |
230 | |
231 | |
232 | static struct file_operations my_operations = { |
233 | .open = my_open, |
234 | }; |
235 | |
236 | int init_module(void) |
237 | { |
238 | pentry = create_proc_entry("testfrwlock", 0444, NULL); |
239 | if (pentry) |
240 | pentry->proc_fops = &my_operations; |
241 | |
242 | printk("NR_CPUS : %d\n", NR_CPUS); |
243 | printk("THREAD_ROFFSET : %lX\n", THREAD_ROFFSET); |
244 | printk("THREAD_RMASK : %lX\n", THREAD_RMASK); |
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245 | printk("SOFTIRQ_ROFFSET : %lX\n", SOFTIRQ_ROFFSET); |
246 | printk("SOFTIRQ_RMASK : %lX\n", SOFTIRQ_RMASK); |
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247 | printk("HARDIRQ_ROFFSET : %lX\n", HARDIRQ_ROFFSET); |
248 | printk("HARDIRQ_RMASK : %lX\n", HARDIRQ_RMASK); |
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249 | printk("SUBSCRIBERS_WOFFSET : %lX\n", SUBSCRIBERS_WOFFSET); |
250 | printk("SUBSCRIBERS_WMASK : %lX\n", SUBSCRIBERS_WMASK); |
251 | printk("WRITER_MUTEX : %lX\n", WRITER_MUTEX); |
252 | printk("SOFTIRQ_WMASK : %lX\n", SOFTIRQ_WMASK); |
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253 | printk("HARDIRQ_WMASK : %lX\n", HARDIRQ_WMASK); |
254 | |
255 | return 0; |
256 | } |
257 | |
258 | void cleanup_module(void) |
259 | { |
260 | remove_proc_entry("testfrwlock", NULL); |
261 | } |
262 | |
263 | MODULE_LICENSE("GPL"); |
264 | MODULE_AUTHOR("Mathieu Desnoyers"); |
265 | MODULE_DESCRIPTION("Fair rwlock test"); |