linux/lib/test_rhashtable.c
Phil Sutter 9e9089e5a2 rhashtable-test: retry insert operations
After adding cond_resched() calls to threadfunc(), a surprisingly high
rate of insert failures occurred probably due to table resizes getting a
better chance to run in background. To not soften up the remaining
tests, retry inserts until they either succeed or fail permanently.

Also change the non-threaded test to retry insert operations, too.

Suggested-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-11-23 12:36:08 -05:00

417 lines
9.8 KiB
C

/*
* Resizable, Scalable, Concurrent Hash Table
*
* Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
* Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
*
* 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.
*/
/**************************************************************************
* Self Test
**************************************************************************/
#include <linux/init.h>
#include <linux/jhash.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/rcupdate.h>
#include <linux/rhashtable.h>
#include <linux/semaphore.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/vmalloc.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)");
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)");
static int tcount = 10;
module_param(tcount, int, 0);
MODULE_PARM_DESC(tcount, "Number of threads to spawn (default: 10)");
struct test_obj {
int value;
struct rhash_head node;
};
struct thread_data {
int id;
struct task_struct *task;
struct test_obj *objs;
};
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),
.hashfn = jhash,
.nulls_base = (3U << RHT_BASE_SHIFT),
};
static struct semaphore prestart_sem;
static struct semaphore startup_sem = __SEMAPHORE_INITIALIZER(startup_sem, 0);
static int insert_retry(struct rhashtable *ht, struct rhash_head *obj,
const struct rhashtable_params params)
{
int err, retries = -1;
do {
retries++;
cond_resched();
err = rhashtable_insert_fast(ht, obj, params);
} while (err == -EBUSY);
return err ? : retries;
}
static int __init test_rht_lookup(struct rhashtable *ht)
{
unsigned int 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) {
pr_warn("Test failed: Could not find key %u\n", key);
return -ENOENT;
} else if (!expected && obj) {
pr_warn("Test failed: Unexpected entry found for key %u\n",
key);
return -EEXIST;
} else if (expected && obj) {
if (obj->value != i) {
pr_warn("Test failed: Lookup value mismatch %u!=%u\n",
obj->value, i);
return -EINVAL;
}
}
cond_resched_rcu();
}
return 0;
}
static void test_bucket_stats(struct rhashtable *ht)
{
unsigned int err, total = 0, chain_len = 0;
struct rhashtable_iter hti;
struct rhash_head *pos;
err = rhashtable_walk_init(ht, &hti);
if (err) {
pr_warn("Test failed: allocation error");
return;
}
err = rhashtable_walk_start(&hti);
if (err && err != -EAGAIN) {
pr_warn("Test failed: iterator failed: %d\n", err);
return;
}
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;
}
total++;
}
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 != entries)
pr_warn("Test failed: Total count mismatch ^^^");
}
static s64 __init test_rhashtable(struct rhashtable *ht)
{
struct test_obj *obj;
int err;
unsigned int i, insert_retries = 0;
s64 start, end;
/*
* Insertion Test:
* Insert entries into table with all keys even numbers
*/
pr_info(" Adding %d keys\n", entries);
start = ktime_get_ns();
for (i = 0; i < entries; i++) {
struct test_obj *obj = &array[i];
obj->value = i * 2;
err = insert_retry(ht, &obj->node, test_rht_params);
if (err > 0)
insert_retries += err;
else if (err)
return err;
}
if (insert_retries)
pr_info(" %u insertions retried due to memory pressure\n",
insert_retries);
test_bucket_stats(ht);
rcu_read_lock();
test_rht_lookup(ht);
rcu_read_unlock();
test_bucket_stats(ht);
pr_info(" Deleting %d keys\n", entries);
for (i = 0; i < entries; i++) {
u32 key = i * 2;
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);
}
cond_resched();
}
end = ktime_get_ns();
pr_info(" Duration of test: %lld ns\n", end - start);
return end - start;
}
static struct rhashtable ht;
static int thread_lookup_test(struct thread_data *tdata)
{
int i, err = 0;
for (i = 0; i < entries; i++) {
struct test_obj *obj;
int key = (tdata->id << 16) | i;
obj = rhashtable_lookup_fast(&ht, &key, test_rht_params);
if (obj && (tdata->objs[i].value == TEST_INSERT_FAIL)) {
pr_err(" found unexpected object %d\n", key);
err++;
} else if (!obj && (tdata->objs[i].value != TEST_INSERT_FAIL)) {
pr_err(" object %d not found!\n", key);
err++;
} else if (obj && (obj->value != key)) {
pr_err(" wrong object returned (got %d, expected %d)\n",
obj->value, key);
err++;
}
cond_resched();
}
return err;
}
static int threadfunc(void *data)
{
int i, step, err = 0, insert_retries = 0;
struct thread_data *tdata = data;
up(&prestart_sem);
if (down_interruptible(&startup_sem))
pr_err(" thread[%d]: down_interruptible failed\n", tdata->id);
for (i = 0; i < entries; i++) {
tdata->objs[i].value = (tdata->id << 16) | i;
err = insert_retry(&ht, &tdata->objs[i].node, test_rht_params);
if (err > 0) {
insert_retries += err;
} else if (err) {
pr_err(" thread[%d]: rhashtable_insert_fast failed\n",
tdata->id);
goto out;
}
}
if (insert_retries)
pr_info(" thread[%d]: %u insertions retried due to memory pressure\n",
tdata->id, insert_retries);
err = thread_lookup_test(tdata);
if (err) {
pr_err(" thread[%d]: rhashtable_lookup_test failed\n",
tdata->id);
goto out;
}
for (step = 10; step > 0; step--) {
for (i = 0; i < entries; i += step) {
if (tdata->objs[i].value == TEST_INSERT_FAIL)
continue;
err = rhashtable_remove_fast(&ht, &tdata->objs[i].node,
test_rht_params);
if (err) {
pr_err(" thread[%d]: rhashtable_remove_fast failed\n",
tdata->id);
goto out;
}
tdata->objs[i].value = TEST_INSERT_FAIL;
cond_resched();
}
err = thread_lookup_test(tdata);
if (err) {
pr_err(" thread[%d]: rhashtable_lookup_test (2) failed\n",
tdata->id);
goto out;
}
}
out:
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
}
return err;
}
static int __init test_rht_init(void)
{
int i, err, started_threads = 0, failed_threads = 0;
u64 total_time = 0;
struct thread_data *tdata;
struct test_obj *objs;
entries = min(entries, MAX_ENTRIES);
test_rht_params.automatic_shrinking = shrinking;
test_rht_params.max_size = max_size;
test_rht_params.nelem_hint = size;
pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
size, max_size, shrinking);
for (i = 0; i < runs; i++) {
s64 time;
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;
}
do_div(total_time, runs);
pr_info("Average test time: %llu\n", total_time);
if (!tcount)
return 0;
pr_info("Testing concurrent rhashtable access from %d threads\n",
tcount);
sema_init(&prestart_sem, 1 - tcount);
tdata = vzalloc(tcount * sizeof(struct thread_data));
if (!tdata)
return -ENOMEM;
objs = vzalloc(tcount * entries * sizeof(struct test_obj));
if (!objs) {
vfree(tdata);
return -ENOMEM;
}
err = rhashtable_init(&ht, &test_rht_params);
if (err < 0) {
pr_warn("Test failed: Unable to initialize hashtable: %d\n",
err);
vfree(tdata);
vfree(objs);
return -EINVAL;
}
for (i = 0; i < tcount; i++) {
tdata[i].id = i;
tdata[i].objs = objs + i * entries;
tdata[i].task = kthread_run(threadfunc, &tdata[i],
"rhashtable_thrad[%d]", i);
if (IS_ERR(tdata[i].task))
pr_err(" kthread_run failed for thread %d\n", i);
else
started_threads++;
}
if (down_interruptible(&prestart_sem))
pr_err(" down interruptible failed\n");
for (i = 0; i < tcount; i++)
up(&startup_sem);
for (i = 0; i < tcount; i++) {
if (IS_ERR(tdata[i].task))
continue;
if ((err = kthread_stop(tdata[i].task))) {
pr_warn("Test failed: thread %d returned: %d\n",
i, err);
failed_threads++;
}
}
pr_info("Started %d threads, %d failed\n",
started_threads, failed_threads);
rhashtable_destroy(&ht);
vfree(tdata);
vfree(objs);
return 0;
}
static void __exit test_rht_exit(void)
{
}
module_init(test_rht_init);
module_exit(test_rht_exit);
MODULE_LICENSE("GPL v2");