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0c330a73 PB |
1 | /* |
2 | * AioContext multithreading tests | |
3 | * | |
4 | * Copyright Red Hat, Inc. 2016 | |
5 | * | |
6 | * Authors: | |
7 | * Paolo Bonzini <[email protected]> | |
8 | * | |
9 | * This work is licensed under the terms of the GNU LGPL, version 2 or later. | |
10 | * See the COPYING.LIB file in the top-level directory. | |
11 | */ | |
12 | ||
13 | #include "qemu/osdep.h" | |
14 | #include <glib.h> | |
15 | #include "block/aio.h" | |
16 | #include "qapi/error.h" | |
17 | #include "qemu/coroutine.h" | |
18 | #include "qemu/thread.h" | |
19 | #include "qemu/error-report.h" | |
20 | #include "iothread.h" | |
21 | ||
22 | /* AioContext management */ | |
23 | ||
24 | #define NUM_CONTEXTS 5 | |
25 | ||
26 | static IOThread *threads[NUM_CONTEXTS]; | |
27 | static AioContext *ctx[NUM_CONTEXTS]; | |
28 | static __thread int id = -1; | |
29 | ||
30 | static QemuEvent done_event; | |
31 | ||
32 | /* Run a function synchronously on a remote iothread. */ | |
33 | ||
34 | typedef struct CtxRunData { | |
35 | QEMUBHFunc *cb; | |
36 | void *arg; | |
37 | } CtxRunData; | |
38 | ||
39 | static void ctx_run_bh_cb(void *opaque) | |
40 | { | |
41 | CtxRunData *data = opaque; | |
42 | ||
43 | data->cb(data->arg); | |
44 | qemu_event_set(&done_event); | |
45 | } | |
46 | ||
47 | static void ctx_run(int i, QEMUBHFunc *cb, void *opaque) | |
48 | { | |
49 | CtxRunData data = { | |
50 | .cb = cb, | |
51 | .arg = opaque | |
52 | }; | |
53 | ||
54 | qemu_event_reset(&done_event); | |
55 | aio_bh_schedule_oneshot(ctx[i], ctx_run_bh_cb, &data); | |
56 | qemu_event_wait(&done_event); | |
57 | } | |
58 | ||
59 | /* Starting the iothreads. */ | |
60 | ||
61 | static void set_id_cb(void *opaque) | |
62 | { | |
63 | int *i = opaque; | |
64 | ||
65 | id = *i; | |
66 | } | |
67 | ||
68 | static void create_aio_contexts(void) | |
69 | { | |
70 | int i; | |
71 | ||
72 | for (i = 0; i < NUM_CONTEXTS; i++) { | |
73 | threads[i] = iothread_new(); | |
74 | ctx[i] = iothread_get_aio_context(threads[i]); | |
75 | } | |
76 | ||
77 | qemu_event_init(&done_event, false); | |
78 | for (i = 0; i < NUM_CONTEXTS; i++) { | |
79 | ctx_run(i, set_id_cb, &i); | |
80 | } | |
81 | } | |
82 | ||
83 | /* Stopping the iothreads. */ | |
84 | ||
85 | static void join_aio_contexts(void) | |
86 | { | |
87 | int i; | |
88 | ||
89 | for (i = 0; i < NUM_CONTEXTS; i++) { | |
90 | aio_context_ref(ctx[i]); | |
91 | } | |
92 | for (i = 0; i < NUM_CONTEXTS; i++) { | |
93 | iothread_join(threads[i]); | |
94 | } | |
95 | for (i = 0; i < NUM_CONTEXTS; i++) { | |
96 | aio_context_unref(ctx[i]); | |
97 | } | |
98 | qemu_event_destroy(&done_event); | |
99 | } | |
100 | ||
101 | /* Basic test for the stuff above. */ | |
102 | ||
103 | static void test_lifecycle(void) | |
104 | { | |
105 | create_aio_contexts(); | |
106 | join_aio_contexts(); | |
107 | } | |
108 | ||
109 | /* aio_co_schedule test. */ | |
110 | ||
111 | static Coroutine *to_schedule[NUM_CONTEXTS]; | |
112 | ||
113 | static bool now_stopping; | |
114 | ||
115 | static int count_retry; | |
116 | static int count_here; | |
117 | static int count_other; | |
118 | ||
119 | static bool schedule_next(int n) | |
120 | { | |
121 | Coroutine *co; | |
122 | ||
123 | co = atomic_xchg(&to_schedule[n], NULL); | |
124 | if (!co) { | |
125 | atomic_inc(&count_retry); | |
126 | return false; | |
127 | } | |
128 | ||
129 | if (n == id) { | |
130 | atomic_inc(&count_here); | |
131 | } else { | |
132 | atomic_inc(&count_other); | |
133 | } | |
134 | ||
135 | aio_co_schedule(ctx[n], co); | |
136 | return true; | |
137 | } | |
138 | ||
139 | static void finish_cb(void *opaque) | |
140 | { | |
141 | schedule_next(id); | |
142 | } | |
143 | ||
144 | static coroutine_fn void test_multi_co_schedule_entry(void *opaque) | |
145 | { | |
146 | g_assert(to_schedule[id] == NULL); | |
147 | atomic_mb_set(&to_schedule[id], qemu_coroutine_self()); | |
148 | ||
149 | while (!atomic_mb_read(&now_stopping)) { | |
150 | int n; | |
151 | ||
152 | n = g_test_rand_int_range(0, NUM_CONTEXTS); | |
153 | schedule_next(n); | |
154 | qemu_coroutine_yield(); | |
155 | ||
156 | g_assert(to_schedule[id] == NULL); | |
157 | atomic_mb_set(&to_schedule[id], qemu_coroutine_self()); | |
158 | } | |
159 | } | |
160 | ||
161 | ||
162 | static void test_multi_co_schedule(int seconds) | |
163 | { | |
164 | int i; | |
165 | ||
166 | count_here = count_other = count_retry = 0; | |
167 | now_stopping = false; | |
168 | ||
169 | create_aio_contexts(); | |
170 | for (i = 0; i < NUM_CONTEXTS; i++) { | |
171 | Coroutine *co1 = qemu_coroutine_create(test_multi_co_schedule_entry, NULL); | |
172 | aio_co_schedule(ctx[i], co1); | |
173 | } | |
174 | ||
175 | g_usleep(seconds * 1000000); | |
176 | ||
177 | atomic_mb_set(&now_stopping, true); | |
178 | for (i = 0; i < NUM_CONTEXTS; i++) { | |
179 | ctx_run(i, finish_cb, NULL); | |
180 | to_schedule[i] = NULL; | |
181 | } | |
182 | ||
183 | join_aio_contexts(); | |
184 | g_test_message("scheduled %d, queued %d, retry %d, total %d\n", | |
185 | count_other, count_here, count_retry, | |
186 | count_here + count_other + count_retry); | |
187 | } | |
188 | ||
189 | static void test_multi_co_schedule_1(void) | |
190 | { | |
191 | test_multi_co_schedule(1); | |
192 | } | |
193 | ||
194 | static void test_multi_co_schedule_10(void) | |
195 | { | |
196 | test_multi_co_schedule(10); | |
197 | } | |
198 | ||
fed20a70 PB |
199 | /* CoMutex thread-safety. */ |
200 | ||
201 | static uint32_t atomic_counter; | |
202 | static uint32_t running; | |
203 | static uint32_t counter; | |
204 | static CoMutex comutex; | |
205 | ||
206 | static void coroutine_fn test_multi_co_mutex_entry(void *opaque) | |
207 | { | |
208 | while (!atomic_mb_read(&now_stopping)) { | |
209 | qemu_co_mutex_lock(&comutex); | |
210 | counter++; | |
211 | qemu_co_mutex_unlock(&comutex); | |
212 | ||
213 | /* Increase atomic_counter *after* releasing the mutex. Otherwise | |
214 | * there is a chance (it happens about 1 in 3 runs) that the iothread | |
215 | * exits before the coroutine is woken up, causing a spurious | |
216 | * assertion failure. | |
217 | */ | |
218 | atomic_inc(&atomic_counter); | |
219 | } | |
220 | atomic_dec(&running); | |
221 | } | |
222 | ||
223 | static void test_multi_co_mutex(int threads, int seconds) | |
224 | { | |
225 | int i; | |
226 | ||
227 | qemu_co_mutex_init(&comutex); | |
228 | counter = 0; | |
229 | atomic_counter = 0; | |
230 | now_stopping = false; | |
231 | ||
232 | create_aio_contexts(); | |
233 | assert(threads <= NUM_CONTEXTS); | |
234 | running = threads; | |
235 | for (i = 0; i < threads; i++) { | |
236 | Coroutine *co1 = qemu_coroutine_create(test_multi_co_mutex_entry, NULL); | |
237 | aio_co_schedule(ctx[i], co1); | |
238 | } | |
239 | ||
240 | g_usleep(seconds * 1000000); | |
241 | ||
242 | atomic_mb_set(&now_stopping, true); | |
243 | while (running > 0) { | |
244 | g_usleep(100000); | |
245 | } | |
246 | ||
247 | join_aio_contexts(); | |
248 | g_test_message("%d iterations/second\n", counter / seconds); | |
249 | g_assert_cmpint(counter, ==, atomic_counter); | |
250 | } | |
251 | ||
252 | /* Testing with NUM_CONTEXTS threads focuses on the queue. The mutex however | |
253 | * is too contended (and the threads spend too much time in aio_poll) | |
254 | * to actually stress the handoff protocol. | |
255 | */ | |
256 | static void test_multi_co_mutex_1(void) | |
257 | { | |
258 | test_multi_co_mutex(NUM_CONTEXTS, 1); | |
259 | } | |
260 | ||
261 | static void test_multi_co_mutex_10(void) | |
262 | { | |
263 | test_multi_co_mutex(NUM_CONTEXTS, 10); | |
264 | } | |
265 | ||
266 | /* Testing with fewer threads stresses the handoff protocol too. Still, the | |
267 | * case where the locker _can_ pick up a handoff is very rare, happening | |
268 | * about 10 times in 1 million, so increase the runtime a bit compared to | |
269 | * other "quick" testcases that only run for 1 second. | |
270 | */ | |
271 | static void test_multi_co_mutex_2_3(void) | |
272 | { | |
273 | test_multi_co_mutex(2, 3); | |
274 | } | |
275 | ||
276 | static void test_multi_co_mutex_2_30(void) | |
277 | { | |
278 | test_multi_co_mutex(2, 30); | |
279 | } | |
280 | ||
c05df34a PB |
281 | /* Same test with fair mutexes, for performance comparison. */ |
282 | ||
283 | #ifdef CONFIG_LINUX | |
284 | #include "qemu/futex.h" | |
285 | ||
286 | /* The nodes for the mutex reside in this structure (on which we try to avoid | |
287 | * false sharing). The head of the mutex is in the "mutex_head" variable. | |
288 | */ | |
289 | static struct { | |
290 | int next, locked; | |
291 | int padding[14]; | |
292 | } nodes[NUM_CONTEXTS] __attribute__((__aligned__(64))); | |
293 | ||
294 | static int mutex_head = -1; | |
295 | ||
296 | static void mcs_mutex_lock(void) | |
297 | { | |
298 | int prev; | |
299 | ||
300 | nodes[id].next = -1; | |
301 | nodes[id].locked = 1; | |
302 | prev = atomic_xchg(&mutex_head, id); | |
303 | if (prev != -1) { | |
304 | atomic_set(&nodes[prev].next, id); | |
305 | qemu_futex_wait(&nodes[id].locked, 1); | |
306 | } | |
307 | } | |
308 | ||
309 | static void mcs_mutex_unlock(void) | |
310 | { | |
311 | int next; | |
3b1d8169 | 312 | if (atomic_read(&nodes[id].next) == -1) { |
c05df34a PB |
313 | if (atomic_read(&mutex_head) == id && |
314 | atomic_cmpxchg(&mutex_head, id, -1) == id) { | |
315 | /* Last item in the list, exit. */ | |
316 | return; | |
317 | } | |
318 | while (atomic_read(&nodes[id].next) == -1) { | |
319 | /* mcs_mutex_lock did the xchg, but has not updated | |
320 | * nodes[prev].next yet. | |
321 | */ | |
322 | } | |
323 | } | |
324 | ||
325 | /* Wake up the next in line. */ | |
3b1d8169 | 326 | next = atomic_read(&nodes[id].next); |
c05df34a PB |
327 | nodes[next].locked = 0; |
328 | qemu_futex_wake(&nodes[next].locked, 1); | |
329 | } | |
330 | ||
331 | static void test_multi_fair_mutex_entry(void *opaque) | |
332 | { | |
333 | while (!atomic_mb_read(&now_stopping)) { | |
334 | mcs_mutex_lock(); | |
335 | counter++; | |
336 | mcs_mutex_unlock(); | |
337 | atomic_inc(&atomic_counter); | |
338 | } | |
339 | atomic_dec(&running); | |
340 | } | |
341 | ||
342 | static void test_multi_fair_mutex(int threads, int seconds) | |
343 | { | |
344 | int i; | |
345 | ||
346 | assert(mutex_head == -1); | |
347 | counter = 0; | |
348 | atomic_counter = 0; | |
349 | now_stopping = false; | |
350 | ||
351 | create_aio_contexts(); | |
352 | assert(threads <= NUM_CONTEXTS); | |
353 | running = threads; | |
354 | for (i = 0; i < threads; i++) { | |
355 | Coroutine *co1 = qemu_coroutine_create(test_multi_fair_mutex_entry, NULL); | |
356 | aio_co_schedule(ctx[i], co1); | |
357 | } | |
358 | ||
359 | g_usleep(seconds * 1000000); | |
360 | ||
361 | atomic_mb_set(&now_stopping, true); | |
362 | while (running > 0) { | |
363 | g_usleep(100000); | |
364 | } | |
365 | ||
366 | join_aio_contexts(); | |
367 | g_test_message("%d iterations/second\n", counter / seconds); | |
368 | g_assert_cmpint(counter, ==, atomic_counter); | |
369 | } | |
370 | ||
371 | static void test_multi_fair_mutex_1(void) | |
372 | { | |
373 | test_multi_fair_mutex(NUM_CONTEXTS, 1); | |
374 | } | |
375 | ||
376 | static void test_multi_fair_mutex_10(void) | |
377 | { | |
378 | test_multi_fair_mutex(NUM_CONTEXTS, 10); | |
379 | } | |
380 | #endif | |
381 | ||
382 | /* Same test with pthread mutexes, for performance comparison and | |
383 | * portability. */ | |
384 | ||
385 | static QemuMutex mutex; | |
386 | ||
387 | static void test_multi_mutex_entry(void *opaque) | |
388 | { | |
389 | while (!atomic_mb_read(&now_stopping)) { | |
390 | qemu_mutex_lock(&mutex); | |
391 | counter++; | |
392 | qemu_mutex_unlock(&mutex); | |
393 | atomic_inc(&atomic_counter); | |
394 | } | |
395 | atomic_dec(&running); | |
396 | } | |
397 | ||
398 | static void test_multi_mutex(int threads, int seconds) | |
399 | { | |
400 | int i; | |
401 | ||
402 | qemu_mutex_init(&mutex); | |
403 | counter = 0; | |
404 | atomic_counter = 0; | |
405 | now_stopping = false; | |
406 | ||
407 | create_aio_contexts(); | |
408 | assert(threads <= NUM_CONTEXTS); | |
409 | running = threads; | |
410 | for (i = 0; i < threads; i++) { | |
411 | Coroutine *co1 = qemu_coroutine_create(test_multi_mutex_entry, NULL); | |
412 | aio_co_schedule(ctx[i], co1); | |
413 | } | |
414 | ||
415 | g_usleep(seconds * 1000000); | |
416 | ||
417 | atomic_mb_set(&now_stopping, true); | |
418 | while (running > 0) { | |
419 | g_usleep(100000); | |
420 | } | |
421 | ||
422 | join_aio_contexts(); | |
423 | g_test_message("%d iterations/second\n", counter / seconds); | |
424 | g_assert_cmpint(counter, ==, atomic_counter); | |
425 | } | |
426 | ||
427 | static void test_multi_mutex_1(void) | |
428 | { | |
429 | test_multi_mutex(NUM_CONTEXTS, 1); | |
430 | } | |
431 | ||
432 | static void test_multi_mutex_10(void) | |
433 | { | |
434 | test_multi_mutex(NUM_CONTEXTS, 10); | |
435 | } | |
436 | ||
0c330a73 PB |
437 | /* End of tests. */ |
438 | ||
439 | int main(int argc, char **argv) | |
440 | { | |
3f53bc61 | 441 | init_clocks(NULL); |
0c330a73 PB |
442 | |
443 | g_test_init(&argc, &argv, NULL); | |
444 | g_test_add_func("/aio/multi/lifecycle", test_lifecycle); | |
445 | if (g_test_quick()) { | |
446 | g_test_add_func("/aio/multi/schedule", test_multi_co_schedule_1); | |
fed20a70 PB |
447 | g_test_add_func("/aio/multi/mutex/contended", test_multi_co_mutex_1); |
448 | g_test_add_func("/aio/multi/mutex/handoff", test_multi_co_mutex_2_3); | |
c05df34a PB |
449 | #ifdef CONFIG_LINUX |
450 | g_test_add_func("/aio/multi/mutex/mcs", test_multi_fair_mutex_1); | |
451 | #endif | |
452 | g_test_add_func("/aio/multi/mutex/pthread", test_multi_mutex_1); | |
0c330a73 PB |
453 | } else { |
454 | g_test_add_func("/aio/multi/schedule", test_multi_co_schedule_10); | |
fed20a70 PB |
455 | g_test_add_func("/aio/multi/mutex/contended", test_multi_co_mutex_10); |
456 | g_test_add_func("/aio/multi/mutex/handoff", test_multi_co_mutex_2_30); | |
c05df34a PB |
457 | #ifdef CONFIG_LINUX |
458 | g_test_add_func("/aio/multi/mutex/mcs", test_multi_fair_mutex_10); | |
459 | #endif | |
460 | g_test_add_func("/aio/multi/mutex/pthread", test_multi_mutex_10); | |
0c330a73 PB |
461 | } |
462 | return g_test_run(); | |
463 | } |