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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>
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David S. Miller committed May 4, 2015
2 parents 7a85202 + 67b7cbf commit 1030822
Showing 1 changed file with 123 additions and 91 deletions.
214 changes: 123 additions & 91 deletions lib/test_rhashtable.c
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Original file line number Diff line number Diff line change
@@ -1,14 +1,9 @@
/*
* 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.
Expand All @@ -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),
Expand All @@ -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) {
Expand All @@ -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;
}
}
Expand All @@ -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)
Expand Down

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