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Linux/lib/test_rhashtable.c

  1 /*
  2  * Resizable, Scalable, Concurrent Hash Table
  3  *
  4  * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
  5  * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
  6  *
  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.
 10  */
 11 
 12 /**************************************************************************
 13  * Self Test
 14  **************************************************************************/
 15 
 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>
 27 
 28 #define MAX_ENTRIES     1000000
 29 #define TEST_INSERT_FAIL INT_MAX
 30 
 31 static int entries = 50000;
 32 module_param(entries, int, 0);
 33 MODULE_PARM_DESC(entries, "Number of entries to add (default: 50000)");
 34 
 35 static int runs = 4;
 36 module_param(runs, int, 0);
 37 MODULE_PARM_DESC(runs, "Number of test runs per variant (default: 4)");
 38 
 39 static int max_size = 0;
 40 module_param(max_size, int, 0);
 41 MODULE_PARM_DESC(max_size, "Maximum table size (default: calculated)");
 42 
 43 static bool shrinking = false;
 44 module_param(shrinking, bool, 0);
 45 MODULE_PARM_DESC(shrinking, "Enable automatic shrinking (default: off)");
 46 
 47 static int size = 8;
 48 module_param(size, int, 0);
 49 MODULE_PARM_DESC(size, "Initial size hint of table (default: 8)");
 50 
 51 static int tcount = 10;
 52 module_param(tcount, int, 0);
 53 MODULE_PARM_DESC(tcount, "Number of threads to spawn (default: 10)");
 54 
 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)");
 58 
 59 struct test_obj {
 60         int                     value;
 61         struct rhash_head       node;
 62 };
 63 
 64 struct thread_data {
 65         int id;
 66         struct task_struct *task;
 67         struct test_obj *objs;
 68 };
 69 
 70 static struct test_obj array[MAX_ENTRIES];
 71 
 72 static struct rhashtable_params test_rht_params = {
 73         .head_offset = offsetof(struct test_obj, node),
 74         .key_offset = offsetof(struct test_obj, value),
 75         .key_len = sizeof(int),
 76         .hashfn = jhash,
 77         .nulls_base = (3U << RHT_BASE_SHIFT),
 78 };
 79 
 80 static struct semaphore prestart_sem;
 81 static struct semaphore startup_sem = __SEMAPHORE_INITIALIZER(startup_sem, 0);
 82 
 83 static int insert_retry(struct rhashtable *ht, struct rhash_head *obj,
 84                         const struct rhashtable_params params)
 85 {
 86         int err, retries = -1, enomem_retries = 0;
 87 
 88         do {
 89                 retries++;
 90                 cond_resched();
 91                 err = rhashtable_insert_fast(ht, obj, params);
 92                 if (err == -ENOMEM && enomem_retry) {
 93                         enomem_retries++;
 94                         err = -EBUSY;
 95                 }
 96         } while (err == -EBUSY);
 97 
 98         if (enomem_retries)
 99                 pr_info(" %u insertions retried after -ENOMEM\n",
100                         enomem_retries);
101 
102         return err ? : retries;
103 }
104 
105 static int __init test_rht_lookup(struct rhashtable *ht)
106 {
107         unsigned int i;
108 
109         for (i = 0; i < entries * 2; i++) {
110                 struct test_obj *obj;
111                 bool expected = !(i % 2);
112                 u32 key = i;
113 
114                 if (array[i / 2].value == TEST_INSERT_FAIL)
115                         expected = false;
116 
117                 obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
118 
119                 if (expected && !obj) {
120                         pr_warn("Test failed: Could not find key %u\n", key);
121                         return -ENOENT;
122                 } else if (!expected && obj) {
123                         pr_warn("Test failed: Unexpected entry found for key %u\n",
124                                 key);
125                         return -EEXIST;
126                 } else if (expected && obj) {
127                         if (obj->value != i) {
128                                 pr_warn("Test failed: Lookup value mismatch %u!=%u\n",
129                                         obj->value, i);
130                                 return -EINVAL;
131                         }
132                 }
133 
134                 cond_resched_rcu();
135         }
136 
137         return 0;
138 }
139 
140 static void test_bucket_stats(struct rhashtable *ht)
141 {
142         unsigned int err, total = 0, chain_len = 0;
143         struct rhashtable_iter hti;
144         struct rhash_head *pos;
145 
146         err = rhashtable_walk_init(ht, &hti, GFP_KERNEL);
147         if (err) {
148                 pr_warn("Test failed: allocation error");
149                 return;
150         }
151 
152         err = rhashtable_walk_start(&hti);
153         if (err && err != -EAGAIN) {
154                 pr_warn("Test failed: iterator failed: %d\n", err);
155                 return;
156         }
157 
158         while ((pos = rhashtable_walk_next(&hti))) {
159                 if (PTR_ERR(pos) == -EAGAIN) {
160                         pr_info("Info: encountered resize\n");
161                         chain_len++;
162                         continue;
163                 } else if (IS_ERR(pos)) {
164                         pr_warn("Test failed: rhashtable_walk_next() error: %ld\n",
165                                 PTR_ERR(pos));
166                         break;
167                 }
168 
169                 total++;
170         }
171 
172         rhashtable_walk_stop(&hti);
173         rhashtable_walk_exit(&hti);
174 
175         pr_info("  Traversal complete: counted=%u, nelems=%u, entries=%d, table-jumps=%u\n",
176                 total, atomic_read(&ht->nelems), entries, chain_len);
177 
178         if (total != atomic_read(&ht->nelems) || total != entries)
179                 pr_warn("Test failed: Total count mismatch ^^^");
180 }
181 
182 static s64 __init test_rhashtable(struct rhashtable *ht)
183 {
184         struct test_obj *obj;
185         int err;
186         unsigned int i, insert_retries = 0;
187         s64 start, end;
188 
189         /*
190          * Insertion Test:
191          * Insert entries into table with all keys even numbers
192          */
193         pr_info("  Adding %d keys\n", entries);
194         start = ktime_get_ns();
195         for (i = 0; i < entries; i++) {
196                 struct test_obj *obj = &array[i];
197 
198                 obj->value = i * 2;
199                 err = insert_retry(ht, &obj->node, test_rht_params);
200                 if (err > 0)
201                         insert_retries += err;
202                 else if (err)
203                         return err;
204         }
205 
206         if (insert_retries)
207                 pr_info("  %u insertions retried due to memory pressure\n",
208                         insert_retries);
209 
210         test_bucket_stats(ht);
211         rcu_read_lock();
212         test_rht_lookup(ht);
213         rcu_read_unlock();
214 
215         test_bucket_stats(ht);
216 
217         pr_info("  Deleting %d keys\n", entries);
218         for (i = 0; i < entries; i++) {
219                 u32 key = i * 2;
220 
221                 if (array[i].value != TEST_INSERT_FAIL) {
222                         obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
223                         BUG_ON(!obj);
224 
225                         rhashtable_remove_fast(ht, &obj->node, test_rht_params);
226                 }
227 
228                 cond_resched();
229         }
230 
231         end = ktime_get_ns();
232         pr_info("  Duration of test: %lld ns\n", end - start);
233 
234         return end - start;
235 }
236 
237 static struct rhashtable ht;
238 
239 static int thread_lookup_test(struct thread_data *tdata)
240 {
241         int i, err = 0;
242 
243         for (i = 0; i < entries; i++) {
244                 struct test_obj *obj;
245                 int key = (tdata->id << 16) | i;
246 
247                 obj = rhashtable_lookup_fast(&ht, &key, test_rht_params);
248                 if (obj && (tdata->objs[i].value == TEST_INSERT_FAIL)) {
249                         pr_err("  found unexpected object %d\n", key);
250                         err++;
251                 } else if (!obj && (tdata->objs[i].value != TEST_INSERT_FAIL)) {
252                         pr_err("  object %d not found!\n", key);
253                         err++;
254                 } else if (obj && (obj->value != key)) {
255                         pr_err("  wrong object returned (got %d, expected %d)\n",
256                                obj->value, key);
257                         err++;
258                 }
259 
260                 cond_resched();
261         }
262         return err;
263 }
264 
265 static int threadfunc(void *data)
266 {
267         int i, step, err = 0, insert_retries = 0;
268         struct thread_data *tdata = data;
269 
270         up(&prestart_sem);
271         if (down_interruptible(&startup_sem))
272                 pr_err("  thread[%d]: down_interruptible failed\n", tdata->id);
273 
274         for (i = 0; i < entries; i++) {
275                 tdata->objs[i].value = (tdata->id << 16) | i;
276                 err = insert_retry(&ht, &tdata->objs[i].node, test_rht_params);
277                 if (err > 0) {
278                         insert_retries += err;
279                 } else if (err) {
280                         pr_err("  thread[%d]: rhashtable_insert_fast failed\n",
281                                tdata->id);
282                         goto out;
283                 }
284         }
285         if (insert_retries)
286                 pr_info("  thread[%d]: %u insertions retried due to memory pressure\n",
287                         tdata->id, insert_retries);
288 
289         err = thread_lookup_test(tdata);
290         if (err) {
291                 pr_err("  thread[%d]: rhashtable_lookup_test failed\n",
292                        tdata->id);
293                 goto out;
294         }
295 
296         for (step = 10; step > 0; step--) {
297                 for (i = 0; i < entries; i += step) {
298                         if (tdata->objs[i].value == TEST_INSERT_FAIL)
299                                 continue;
300                         err = rhashtable_remove_fast(&ht, &tdata->objs[i].node,
301                                                      test_rht_params);
302                         if (err) {
303                                 pr_err("  thread[%d]: rhashtable_remove_fast failed\n",
304                                        tdata->id);
305                                 goto out;
306                         }
307                         tdata->objs[i].value = TEST_INSERT_FAIL;
308 
309                         cond_resched();
310                 }
311                 err = thread_lookup_test(tdata);
312                 if (err) {
313                         pr_err("  thread[%d]: rhashtable_lookup_test (2) failed\n",
314                                tdata->id);
315                         goto out;
316                 }
317         }
318 out:
319         while (!kthread_should_stop()) {
320                 set_current_state(TASK_INTERRUPTIBLE);
321                 schedule();
322         }
323         return err;
324 }
325 
326 static int __init test_rht_init(void)
327 {
328         int i, err, started_threads = 0, failed_threads = 0;
329         u64 total_time = 0;
330         struct thread_data *tdata;
331         struct test_obj *objs;
332 
333         entries = min(entries, MAX_ENTRIES);
334 
335         test_rht_params.automatic_shrinking = shrinking;
336         test_rht_params.max_size = max_size ? : roundup_pow_of_two(entries);
337         test_rht_params.nelem_hint = size;
338 
339         pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
340                 size, max_size, shrinking);
341 
342         for (i = 0; i < runs; i++) {
343                 s64 time;
344 
345                 pr_info("Test %02d:\n", i);
346                 memset(&array, 0, sizeof(array));
347                 err = rhashtable_init(&ht, &test_rht_params);
348                 if (err < 0) {
349                         pr_warn("Test failed: Unable to initialize hashtable: %d\n",
350                                 err);
351                         continue;
352                 }
353 
354                 time = test_rhashtable(&ht);
355                 rhashtable_destroy(&ht);
356                 if (time < 0) {
357                         pr_warn("Test failed: return code %lld\n", time);
358                         return -EINVAL;
359                 }
360 
361                 total_time += time;
362         }
363 
364         do_div(total_time, runs);
365         pr_info("Average test time: %llu\n", total_time);
366 
367         if (!tcount)
368                 return 0;
369 
370         pr_info("Testing concurrent rhashtable access from %d threads\n",
371                 tcount);
372         sema_init(&prestart_sem, 1 - tcount);
373         tdata = vzalloc(tcount * sizeof(struct thread_data));
374         if (!tdata)
375                 return -ENOMEM;
376         objs  = vzalloc(tcount * entries * sizeof(struct test_obj));
377         if (!objs) {
378                 vfree(tdata);
379                 return -ENOMEM;
380         }
381 
382         test_rht_params.max_size = max_size ? :
383                                    roundup_pow_of_two(tcount * entries);
384         err = rhashtable_init(&ht, &test_rht_params);
385         if (err < 0) {
386                 pr_warn("Test failed: Unable to initialize hashtable: %d\n",
387                         err);
388                 vfree(tdata);
389                 vfree(objs);
390                 return -EINVAL;
391         }
392         for (i = 0; i < tcount; i++) {
393                 tdata[i].id = i;
394                 tdata[i].objs = objs + i * entries;
395                 tdata[i].task = kthread_run(threadfunc, &tdata[i],
396                                             "rhashtable_thrad[%d]", i);
397                 if (IS_ERR(tdata[i].task))
398                         pr_err(" kthread_run failed for thread %d\n", i);
399                 else
400                         started_threads++;
401         }
402         if (down_interruptible(&prestart_sem))
403                 pr_err("  down interruptible failed\n");
404         for (i = 0; i < tcount; i++)
405                 up(&startup_sem);
406         for (i = 0; i < tcount; i++) {
407                 if (IS_ERR(tdata[i].task))
408                         continue;
409                 if ((err = kthread_stop(tdata[i].task))) {
410                         pr_warn("Test failed: thread %d returned: %d\n",
411                                 i, err);
412                         failed_threads++;
413                 }
414         }
415         pr_info("Started %d threads, %d failed\n",
416                 started_threads, failed_threads);
417         rhashtable_destroy(&ht);
418         vfree(tdata);
419         vfree(objs);
420         return 0;
421 }
422 
423 static void __exit test_rht_exit(void)
424 {
425 }
426 
427 module_init(test_rht_init);
428 module_exit(test_rht_exit);
429 
430 MODULE_LICENSE("GPL v2");
431 

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