2 * Resizable, Scalable, Concurrent Hash Table
4 * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
5 * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
12 /**************************************************************************
14 **************************************************************************/
16 #include <linux/init.h>
17 #include <linux/jhash.h>
18 #include <linux/kernel.h>
19 #include <linux/kthread.h>
20 #include <linux/module.h>
21 #include <linux/rcupdate.h>
22 #include <linux/rhashtable.h>
23 #include <linux/semaphore.h>
24 #include <linux/slab.h>
25 #include <linux/sched.h>
26 #include <linux/vmalloc.h>
28 #define MAX_ENTRIES 1000000
29 #define TEST_INSERT_FAIL INT_MAX
31 static int entries = 50000;
32 module_param(entries, int, 0);
33 MODULE_PARM_DESC(entries, "Number of entries to add (default: 50000)");
36 module_param(runs, int, 0);
37 MODULE_PARM_DESC(runs, "Number of test runs per variant (default: 4)");
39 static int max_size = 0;
40 module_param(max_size, int, 0);
41 MODULE_PARM_DESC(max_size, "Maximum table size (default: calculated)");
43 static bool shrinking = false;
44 module_param(shrinking, bool, 0);
45 MODULE_PARM_DESC(shrinking, "Enable automatic shrinking (default: off)");
48 module_param(size, int, 0);
49 MODULE_PARM_DESC(size, "Initial size hint of table (default: 8)");
51 static int tcount = 10;
52 module_param(tcount, int, 0);
53 MODULE_PARM_DESC(tcount, "Number of threads to spawn (default: 10)");
55 static bool enomem_retry = false;
56 module_param(enomem_retry, bool, 0);
57 MODULE_PARM_DESC(enomem_retry, "Retry insert even if -ENOMEM was returned (default: off)");
65 struct test_obj_val value;
66 struct rhash_head node;
71 struct task_struct *task;
72 struct test_obj *objs;
75 static struct test_obj array[MAX_ENTRIES];
77 static struct rhashtable_params test_rht_params = {
78 .head_offset = offsetof(struct test_obj, node),
79 .key_offset = offsetof(struct test_obj, value),
80 .key_len = sizeof(struct test_obj_val),
82 .nulls_base = (3U << RHT_BASE_SHIFT),
85 static struct semaphore prestart_sem;
86 static struct semaphore startup_sem = __SEMAPHORE_INITIALIZER(startup_sem, 0);
88 static int insert_retry(struct rhashtable *ht, struct rhash_head *obj,
89 const struct rhashtable_params params)
91 int err, retries = -1, enomem_retries = 0;
96 err = rhashtable_insert_fast(ht, obj, params);
97 if (err == -ENOMEM && enomem_retry) {
101 } while (err == -EBUSY);
104 pr_info(" %u insertions retried after -ENOMEM\n",
107 return err ? : retries;
110 static int __init test_rht_lookup(struct rhashtable *ht)
114 for (i = 0; i < entries * 2; i++) {
115 struct test_obj *obj;
116 bool expected = !(i % 2);
117 struct test_obj_val key = {
121 if (array[i / 2].value.id == TEST_INSERT_FAIL)
124 obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
126 if (expected && !obj) {
127 pr_warn("Test failed: Could not find key %u\n", key.id);
129 } else if (!expected && obj) {
130 pr_warn("Test failed: Unexpected entry found for key %u\n",
133 } else if (expected && obj) {
134 if (obj->value.id != i) {
135 pr_warn("Test failed: Lookup value mismatch %u!=%u\n",
147 static void test_bucket_stats(struct rhashtable *ht)
149 unsigned int err, total = 0, chain_len = 0;
150 struct rhashtable_iter hti;
151 struct rhash_head *pos;
153 err = rhashtable_walk_init(ht, &hti, GFP_KERNEL);
155 pr_warn("Test failed: allocation error");
159 err = rhashtable_walk_start(&hti);
160 if (err && err != -EAGAIN) {
161 pr_warn("Test failed: iterator failed: %d\n", err);
165 while ((pos = rhashtable_walk_next(&hti))) {
166 if (PTR_ERR(pos) == -EAGAIN) {
167 pr_info("Info: encountered resize\n");
170 } else if (IS_ERR(pos)) {
171 pr_warn("Test failed: rhashtable_walk_next() error: %ld\n",
179 rhashtable_walk_stop(&hti);
180 rhashtable_walk_exit(&hti);
182 pr_info(" Traversal complete: counted=%u, nelems=%u, entries=%d, table-jumps=%u\n",
183 total, atomic_read(&ht->nelems), entries, chain_len);
185 if (total != atomic_read(&ht->nelems) || total != entries)
186 pr_warn("Test failed: Total count mismatch ^^^");
189 static s64 __init test_rhashtable(struct rhashtable *ht)
191 struct test_obj *obj;
193 unsigned int i, insert_retries = 0;
198 * Insert entries into table with all keys even numbers
200 pr_info(" Adding %d keys\n", entries);
201 start = ktime_get_ns();
202 for (i = 0; i < entries; i++) {
203 struct test_obj *obj = &array[i];
205 obj->value.id = i * 2;
206 err = insert_retry(ht, &obj->node, test_rht_params);
208 insert_retries += err;
214 pr_info(" %u insertions retried due to memory pressure\n",
217 test_bucket_stats(ht);
222 test_bucket_stats(ht);
224 pr_info(" Deleting %d keys\n", entries);
225 for (i = 0; i < entries; i++) {
228 if (array[i].value.id != TEST_INSERT_FAIL) {
229 obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
232 rhashtable_remove_fast(ht, &obj->node, test_rht_params);
238 end = ktime_get_ns();
239 pr_info(" Duration of test: %lld ns\n", end - start);
244 static struct rhashtable ht;
246 static int thread_lookup_test(struct thread_data *tdata)
250 for (i = 0; i < entries; i++) {
251 struct test_obj *obj;
252 struct test_obj_val key = {
257 obj = rhashtable_lookup_fast(&ht, &key, test_rht_params);
258 if (obj && (tdata->objs[i].value.id == TEST_INSERT_FAIL)) {
259 pr_err(" found unexpected object %d-%d\n", key.tid, key.id);
261 } else if (!obj && (tdata->objs[i].value.id != TEST_INSERT_FAIL)) {
262 pr_err(" object %d-%d not found!\n", key.tid, key.id);
264 } else if (obj && memcmp(&obj->value, &key, sizeof(key))) {
265 pr_err(" wrong object returned (got %d-%d, expected %d-%d)\n",
266 obj->value.tid, obj->value.id, key.tid, key.id);
275 static int threadfunc(void *data)
277 int i, step, err = 0, insert_retries = 0;
278 struct thread_data *tdata = data;
281 if (down_interruptible(&startup_sem))
282 pr_err(" thread[%d]: down_interruptible failed\n", tdata->id);
284 for (i = 0; i < entries; i++) {
285 tdata->objs[i].value.id = i;
286 tdata->objs[i].value.tid = tdata->id;
287 err = insert_retry(&ht, &tdata->objs[i].node, test_rht_params);
289 insert_retries += err;
291 pr_err(" thread[%d]: rhashtable_insert_fast failed\n",
297 pr_info(" thread[%d]: %u insertions retried due to memory pressure\n",
298 tdata->id, insert_retries);
300 err = thread_lookup_test(tdata);
302 pr_err(" thread[%d]: rhashtable_lookup_test failed\n",
307 for (step = 10; step > 0; step--) {
308 for (i = 0; i < entries; i += step) {
309 if (tdata->objs[i].value.id == TEST_INSERT_FAIL)
311 err = rhashtable_remove_fast(&ht, &tdata->objs[i].node,
314 pr_err(" thread[%d]: rhashtable_remove_fast failed\n",
318 tdata->objs[i].value.id = TEST_INSERT_FAIL;
322 err = thread_lookup_test(tdata);
324 pr_err(" thread[%d]: rhashtable_lookup_test (2) failed\n",
330 while (!kthread_should_stop()) {
331 set_current_state(TASK_INTERRUPTIBLE);
337 static int __init test_rht_init(void)
339 int i, err, started_threads = 0, failed_threads = 0;
341 struct thread_data *tdata;
342 struct test_obj *objs;
344 entries = min(entries, MAX_ENTRIES);
346 test_rht_params.automatic_shrinking = shrinking;
347 test_rht_params.max_size = max_size ? : roundup_pow_of_two(entries);
348 test_rht_params.nelem_hint = size;
350 pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
351 size, max_size, shrinking);
353 for (i = 0; i < runs; i++) {
356 pr_info("Test %02d:\n", i);
357 memset(&array, 0, sizeof(array));
358 err = rhashtable_init(&ht, &test_rht_params);
360 pr_warn("Test failed: Unable to initialize hashtable: %d\n",
365 time = test_rhashtable(&ht);
366 rhashtable_destroy(&ht);
368 pr_warn("Test failed: return code %lld\n", time);
375 do_div(total_time, runs);
376 pr_info("Average test time: %llu\n", total_time);
381 pr_info("Testing concurrent rhashtable access from %d threads\n",
383 sema_init(&prestart_sem, 1 - tcount);
384 tdata = vzalloc(tcount * sizeof(struct thread_data));
387 objs = vzalloc(tcount * entries * sizeof(struct test_obj));
393 test_rht_params.max_size = max_size ? :
394 roundup_pow_of_two(tcount * entries);
395 err = rhashtable_init(&ht, &test_rht_params);
397 pr_warn("Test failed: Unable to initialize hashtable: %d\n",
403 for (i = 0; i < tcount; i++) {
405 tdata[i].objs = objs + i * entries;
406 tdata[i].task = kthread_run(threadfunc, &tdata[i],
407 "rhashtable_thrad[%d]", i);
408 if (IS_ERR(tdata[i].task))
409 pr_err(" kthread_run failed for thread %d\n", i);
413 if (down_interruptible(&prestart_sem))
414 pr_err(" down interruptible failed\n");
415 for (i = 0; i < tcount; i++)
417 for (i = 0; i < tcount; i++) {
418 if (IS_ERR(tdata[i].task))
420 if ((err = kthread_stop(tdata[i].task))) {
421 pr_warn("Test failed: thread %d returned: %d\n",
426 pr_info("Started %d threads, %d failed\n",
427 started_threads, failed_threads);
428 rhashtable_destroy(&ht);
434 static void __exit test_rht_exit(void)
438 module_init(test_rht_init);
439 module_exit(test_rht_exit);
441 MODULE_LICENSE("GPL v2");