Merge branch 'rhashtable-test'

Thomas Graf says:

====================
rhashtable self-test improvements

This series improves the rhashtable self-test to:
  * Avoid allocation of test objects
  * Measure the time of test runs
  * Use the iterator to walk the table for consistency
  * Account for failed insertions due to memory pressure or
    utilization pressure
  * Ignore failed insertions when checking for consistency
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

lib/test_rhashtable.c

 /*
  * Resizable, Scalable, Concurrent Hash Table
  *
- * Copyright (c) 2014 Thomas Graf <tgraf@suug.ch>
+ * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
  * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
  *
- * Based on the following paper:
- * https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf
- *
- * Code partially derived from nft_hash
- *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
@@ -26,20 +21,37 @@
 #include <linux/rhashtable.h>
 #include <linux/slab.h>
 
+#define MAX_ENTRIES	1000000
+#define TEST_INSERT_FAIL INT_MAX
+
+static int entries = 50000;
+module_param(entries, int, 0);
+MODULE_PARM_DESC(entries, "Number of entries to add (default: 50000)");
+
+static int runs = 4;
+module_param(runs, int, 0);
+MODULE_PARM_DESC(runs, "Number of test runs per variant (default: 4)");
+
+static int max_size = 65536;
+module_param(max_size, int, 0);
+MODULE_PARM_DESC(runs, "Maximum table size (default: 65536)");
 
-#define TEST_HT_SIZE	8
-#define TEST_ENTRIES	2048
-#define TEST_PTR	((void *) 0xdeadbeef)
-#define TEST_NEXPANDS	4
+static bool shrinking = false;
+module_param(shrinking, bool, 0);
+MODULE_PARM_DESC(shrinking, "Enable automatic shrinking (default: off)");
+
+static int size = 8;
+module_param(size, int, 0);
+MODULE_PARM_DESC(size, "Initial size hint of table (default: 8)");
 
 struct test_obj {
-	void			*ptr;
 	int			value;
 	struct rhash_head	node;
 };
 
-static const struct rhashtable_params test_rht_params = {
-	.nelem_hint = TEST_HT_SIZE,
+static struct test_obj array[MAX_ENTRIES];
+
+static struct rhashtable_params test_rht_params = {
 	.head_offset = offsetof(struct test_obj, node),
 	.key_offset = offsetof(struct test_obj, value),
 	.key_len = sizeof(int),
@@ -51,11 +63,14 @@ static int __init test_rht_lookup(struct rhashtable *ht)
 {
 	unsigned int i;
 
-	for (i = 0; i < TEST_ENTRIES * 2; i++) {
+	for (i = 0; i < entries * 2; i++) {
 		struct test_obj *obj;
 		bool expected = !(i % 2);
 		u32 key = i;
 
+		if (array[i / 2].value == TEST_INSERT_FAIL)
+			expected = false;
+
 		obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
 
 		if (expected && !obj) {
@@ -66,9 +81,9 @@ static int __init test_rht_lookup(struct rhashtable *ht)
 				key);
 			return -EEXIST;
 		} else if (expected && obj) {
-			if (obj->ptr != TEST_PTR || obj->value != i) {
-				pr_warn("Test failed: Lookup value mismatch %p!=%p, %u!=%u\n",
-					obj->ptr, TEST_PTR, obj->value, i);
+			if (obj->value != i) {
+				pr_warn("Test failed: Lookup value mismatch %u!=%u\n",
+					obj->value, i);
 				return -EINVAL;
 			}
 		}
@@ -77,129 +92,146 @@ static int __init test_rht_lookup(struct rhashtable *ht)
 	return 0;
 }
 
-static void test_bucket_stats(struct rhashtable *ht, bool quiet)
+static void test_bucket_stats(struct rhashtable *ht)
 {
-	unsigned int cnt, rcu_cnt, i, total = 0;
+	unsigned int err, total = 0, chain_len = 0;
+	struct rhashtable_iter hti;
 	struct rhash_head *pos;
-	struct test_obj *obj;
-	struct bucket_table *tbl;
 
-	tbl = rht_dereference_rcu(ht->tbl, ht);
-	for (i = 0; i < tbl->size; i++) {
-		rcu_cnt = cnt = 0;
+	err = rhashtable_walk_init(ht, &hti);
+	if (err) {
+		pr_warn("Test failed: allocation error");
+		return;
+	}
 
-		if (!quiet)
-			pr_info(" [%#4x/%u]", i, tbl->size);
+	err = rhashtable_walk_start(&hti);
+	if (err && err != -EAGAIN) {
+		pr_warn("Test failed: iterator failed: %d\n", err);
+		return;
+	}
 
-		rht_for_each_entry_rcu(obj, pos, tbl, i, node) {
-			cnt++;
-			total++;
-			if (!quiet)
-				pr_cont(" [%p],", obj);
+	while ((pos = rhashtable_walk_next(&hti))) {
+		if (PTR_ERR(pos) == -EAGAIN) {
+			pr_info("Info: encountered resize\n");
+			chain_len++;
+			continue;
+		} else if (IS_ERR(pos)) {
+			pr_warn("Test failed: rhashtable_walk_next() error: %ld\n",
+				PTR_ERR(pos));
+			break;
 		}
 
-		rht_for_each_entry_rcu(obj, pos, tbl, i, node)
-			rcu_cnt++;
-
-		if (rcu_cnt != cnt)
-			pr_warn("Test failed: Chain count mismach %d != %d",
-				cnt, rcu_cnt);
-
-		if (!quiet)
-			pr_cont("\n  [%#x] first element: %p, chain length: %u\n",
-				i, tbl->buckets[i], cnt);
+		total++;
 	}
 
-	pr_info("  Traversal complete: counted=%u, nelems=%u, entries=%d\n",
-		total, atomic_read(&ht->nelems), TEST_ENTRIES);
+	rhashtable_walk_stop(&hti);
+	rhashtable_walk_exit(&hti);
+
+	pr_info("  Traversal complete: counted=%u, nelems=%u, entries=%d, table-jumps=%u\n",
+		total, atomic_read(&ht->nelems), entries, chain_len);
 
-	if (total != atomic_read(&ht->nelems) || total != TEST_ENTRIES)
+	if (total != atomic_read(&ht->nelems) || total != entries)
 		pr_warn("Test failed: Total count mismatch ^^^");
 }
 
-static int __init test_rhashtable(struct rhashtable *ht)
+static s64 __init test_rhashtable(struct rhashtable *ht)
 {
-	struct bucket_table *tbl;
 	struct test_obj *obj;
-	struct rhash_head *pos, *next;
 	int err;
-	unsigned int i;
+	unsigned int i, insert_fails = 0;
+	s64 start, end;
 
 	/*
 	 * Insertion Test:
-	 * Insert TEST_ENTRIES into table with all keys even numbers
+	 * Insert entries into table with all keys even numbers
 	 */
-	pr_info("  Adding %d keys\n", TEST_ENTRIES);
-	for (i = 0; i < TEST_ENTRIES; i++) {
-		struct test_obj *obj;
-
-		obj = kzalloc(sizeof(*obj), GFP_KERNEL);
-		if (!obj) {
-			err = -ENOMEM;
-			goto error;
-		}
+	pr_info("  Adding %d keys\n", entries);
+	start = ktime_get_ns();
+	for (i = 0; i < entries; i++) {
+		struct test_obj *obj = &array[i];
 
-		obj->ptr = TEST_PTR;
 		obj->value = i * 2;
 
 		err = rhashtable_insert_fast(ht, &obj->node, test_rht_params);
-		if (err) {
-			kfree(obj);
-			goto error;
+		if (err == -ENOMEM || err == -EBUSY) {
+			/* Mark failed inserts but continue */
+			obj->value = TEST_INSERT_FAIL;
+			insert_fails++;
+		} else if (err) {
+			return err;
 		}
 	}
 
+	if (insert_fails)
+		pr_info("  %u insertions failed due to memory pressure\n",
+			insert_fails);
+
+	test_bucket_stats(ht);
 	rcu_read_lock();
-	test_bucket_stats(ht, true);
 	test_rht_lookup(ht);
 	rcu_read_unlock();
 
-	rcu_read_lock();
-	test_bucket_stats(ht, true);
-	rcu_read_unlock();
+	test_bucket_stats(ht);
 
-	pr_info("  Deleting %d keys\n", TEST_ENTRIES);
-	for (i = 0; i < TEST_ENTRIES; i++) {
+	pr_info("  Deleting %d keys\n", entries);
+	for (i = 0; i < entries; i++) {
 		u32 key = i * 2;
 
-		obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
-		BUG_ON(!obj);
+		if (array[i].value != TEST_INSERT_FAIL) {
+			obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
+			BUG_ON(!obj);
 
-		rhashtable_remove_fast(ht, &obj->node, test_rht_params);
-		kfree(obj);
+			rhashtable_remove_fast(ht, &obj->node, test_rht_params);
+		}
 	}
 
-	return 0;
-
-error:
-	tbl = rht_dereference_rcu(ht->tbl, ht);
-	for (i = 0; i < tbl->size; i++)
-		rht_for_each_entry_safe(obj, pos, next, tbl, i, node)
-			kfree(obj);
+	end = ktime_get_ns();
+	pr_info("  Duration of test: %lld ns\n", end - start);
 
-	return err;
+	return end - start;
 }
 
 static struct rhashtable ht;
 
 static int __init test_rht_init(void)
 {
-	int err;
+	int i, err;
+	u64 total_time = 0;
 
-	pr_info("Running resizable hashtable tests...\n");
+	entries = min(entries, MAX_ENTRIES);
 
-	err = rhashtable_init(&ht, &test_rht_params);
-	if (err < 0) {
-		pr_warn("Test failed: Unable to initialize hashtable: %d\n",
-			err);
-		return err;
-	}
+	test_rht_params.automatic_shrinking = shrinking;
+	test_rht_params.max_size = max_size;
+	test_rht_params.nelem_hint = size;
 
-	err = test_rhashtable(&ht);
+	pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
+		size, max_size, shrinking);
 
-	rhashtable_destroy(&ht);
+	for (i = 0; i < runs; i++) {
+		s64 time;
 
-	return err;
+		pr_info("Test %02d:\n", i);
+		memset(&array, 0, sizeof(array));
+		err = rhashtable_init(&ht, &test_rht_params);
+		if (err < 0) {
+			pr_warn("Test failed: Unable to initialize hashtable: %d\n",
+				err);
+			continue;
+		}
+
+		time = test_rhashtable(&ht);
+		rhashtable_destroy(&ht);
+		if (time < 0) {
+			pr_warn("Test failed: return code %lld\n", time);
+			return -EINVAL;
+		}
+
+		total_time += time;
+	}
+
+	pr_info("Average test time: %llu\n", total_time / runs);
+
+	return 0;
 }
 
 static void __exit test_rht_exit(void)