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 = 65536;
40 module_param(max_size, int, 0);
41 MODULE_PARM_DESC(runs, "Maximum table size (default: 65536)");
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)");
57 struct rhash_head node;
62 struct task_struct *task;
63 struct test_obj *objs;
66 static struct test_obj array[MAX_ENTRIES];
68 static struct rhashtable_params test_rht_params = {
69 .head_offset = offsetof(struct test_obj, node),
70 .key_offset = offsetof(struct test_obj, value),
71 .key_len = sizeof(int),
73 .nulls_base = (3U << RHT_BASE_SHIFT),
76 static struct semaphore prestart_sem;
77 static struct semaphore startup_sem = __SEMAPHORE_INITIALIZER(startup_sem, 0);
79 static int insert_retry(struct rhashtable *ht, struct rhash_head *obj,
80 const struct rhashtable_params params)
82 int err, retries = -1;
87 err = rhashtable_insert_fast(ht, obj, params);
88 } while (err == -EBUSY);
90 return err ? : retries;
93 static int __init test_rht_lookup(struct rhashtable *ht)
97 for (i = 0; i < entries * 2; i++) {
99 bool expected = !(i % 2);
102 if (array[i / 2].value == TEST_INSERT_FAIL)
105 obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
107 if (expected && !obj) {
108 pr_warn("Test failed: Could not find key %u\n", key);
110 } else if (!expected && obj) {
111 pr_warn("Test failed: Unexpected entry found for key %u\n",
114 } else if (expected && obj) {
115 if (obj->value != i) {
116 pr_warn("Test failed: Lookup value mismatch %u!=%u\n",
128 static void test_bucket_stats(struct rhashtable *ht)
130 unsigned int err, total = 0, chain_len = 0;
131 struct rhashtable_iter hti;
132 struct rhash_head *pos;
134 err = rhashtable_walk_init(ht, &hti);
136 pr_warn("Test failed: allocation error");
140 err = rhashtable_walk_start(&hti);
141 if (err && err != -EAGAIN) {
142 pr_warn("Test failed: iterator failed: %d\n", err);
146 while ((pos = rhashtable_walk_next(&hti))) {
147 if (PTR_ERR(pos) == -EAGAIN) {
148 pr_info("Info: encountered resize\n");
151 } else if (IS_ERR(pos)) {
152 pr_warn("Test failed: rhashtable_walk_next() error: %ld\n",
160 rhashtable_walk_stop(&hti);
161 rhashtable_walk_exit(&hti);
163 pr_info(" Traversal complete: counted=%u, nelems=%u, entries=%d, table-jumps=%u\n",
164 total, atomic_read(&ht->nelems), entries, chain_len);
166 if (total != atomic_read(&ht->nelems) || total != entries)
167 pr_warn("Test failed: Total count mismatch ^^^");
170 static s64 __init test_rhashtable(struct rhashtable *ht)
172 struct test_obj *obj;
174 unsigned int i, insert_retries = 0;
179 * Insert entries into table with all keys even numbers
181 pr_info(" Adding %d keys\n", entries);
182 start = ktime_get_ns();
183 for (i = 0; i < entries; i++) {
184 struct test_obj *obj = &array[i];
187 err = insert_retry(ht, &obj->node, test_rht_params);
189 insert_retries += err;
195 pr_info(" %u insertions retried due to memory pressure\n",
198 test_bucket_stats(ht);
203 test_bucket_stats(ht);
205 pr_info(" Deleting %d keys\n", entries);
206 for (i = 0; i < entries; i++) {
209 if (array[i].value != TEST_INSERT_FAIL) {
210 obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
213 rhashtable_remove_fast(ht, &obj->node, test_rht_params);
219 end = ktime_get_ns();
220 pr_info(" Duration of test: %lld ns\n", end - start);
225 static struct rhashtable ht;
227 static int thread_lookup_test(struct thread_data *tdata)
231 for (i = 0; i < entries; i++) {
232 struct test_obj *obj;
233 int key = (tdata->id << 16) | i;
235 obj = rhashtable_lookup_fast(&ht, &key, test_rht_params);
236 if (obj && (tdata->objs[i].value == TEST_INSERT_FAIL)) {
237 pr_err(" found unexpected object %d\n", key);
239 } else if (!obj && (tdata->objs[i].value != TEST_INSERT_FAIL)) {
240 pr_err(" object %d not found!\n", key);
242 } else if (obj && (obj->value != key)) {
243 pr_err(" wrong object returned (got %d, expected %d)\n",
253 static int threadfunc(void *data)
255 int i, step, err = 0, insert_retries = 0;
256 struct thread_data *tdata = data;
259 if (down_interruptible(&startup_sem))
260 pr_err(" thread[%d]: down_interruptible failed\n", tdata->id);
262 for (i = 0; i < entries; i++) {
263 tdata->objs[i].value = (tdata->id << 16) | i;
264 err = insert_retry(&ht, &tdata->objs[i].node, test_rht_params);
266 insert_retries += err;
268 pr_err(" thread[%d]: rhashtable_insert_fast failed\n",
274 pr_info(" thread[%d]: %u insertions retried due to memory pressure\n",
275 tdata->id, insert_retries);
277 err = thread_lookup_test(tdata);
279 pr_err(" thread[%d]: rhashtable_lookup_test failed\n",
284 for (step = 10; step > 0; step--) {
285 for (i = 0; i < entries; i += step) {
286 if (tdata->objs[i].value == TEST_INSERT_FAIL)
288 err = rhashtable_remove_fast(&ht, &tdata->objs[i].node,
291 pr_err(" thread[%d]: rhashtable_remove_fast failed\n",
295 tdata->objs[i].value = TEST_INSERT_FAIL;
299 err = thread_lookup_test(tdata);
301 pr_err(" thread[%d]: rhashtable_lookup_test (2) failed\n",
307 while (!kthread_should_stop()) {
308 set_current_state(TASK_INTERRUPTIBLE);
314 static int __init test_rht_init(void)
316 int i, err, started_threads = 0, failed_threads = 0;
318 struct thread_data *tdata;
319 struct test_obj *objs;
321 entries = min(entries, MAX_ENTRIES);
323 test_rht_params.automatic_shrinking = shrinking;
324 test_rht_params.max_size = max_size;
325 test_rht_params.nelem_hint = size;
327 pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
328 size, max_size, shrinking);
330 for (i = 0; i < runs; i++) {
333 pr_info("Test %02d:\n", i);
334 memset(&array, 0, sizeof(array));
335 err = rhashtable_init(&ht, &test_rht_params);
337 pr_warn("Test failed: Unable to initialize hashtable: %d\n",
342 time = test_rhashtable(&ht);
343 rhashtable_destroy(&ht);
345 pr_warn("Test failed: return code %lld\n", time);
352 do_div(total_time, runs);
353 pr_info("Average test time: %llu\n", total_time);
358 pr_info("Testing concurrent rhashtable access from %d threads\n",
360 sema_init(&prestart_sem, 1 - tcount);
361 tdata = vzalloc(tcount * sizeof(struct thread_data));
364 objs = vzalloc(tcount * entries * sizeof(struct test_obj));
370 err = rhashtable_init(&ht, &test_rht_params);
372 pr_warn("Test failed: Unable to initialize hashtable: %d\n",
378 for (i = 0; i < tcount; i++) {
380 tdata[i].objs = objs + i * entries;
381 tdata[i].task = kthread_run(threadfunc, &tdata[i],
382 "rhashtable_thrad[%d]", i);
383 if (IS_ERR(tdata[i].task))
384 pr_err(" kthread_run failed for thread %d\n", i);
388 if (down_interruptible(&prestart_sem))
389 pr_err(" down interruptible failed\n");
390 for (i = 0; i < tcount; i++)
392 for (i = 0; i < tcount; i++) {
393 if (IS_ERR(tdata[i].task))
395 if ((err = kthread_stop(tdata[i].task))) {
396 pr_warn("Test failed: thread %d returned: %d\n",
401 pr_info("Started %d threads, %d failed\n",
402 started_threads, failed_threads);
403 rhashtable_destroy(&ht);
409 static void __exit test_rht_exit(void)
413 module_init(test_rht_init);
414 module_exit(test_rht_exit);
416 MODULE_LICENSE("GPL v2");