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![Phil Sutter](/assets/img/avatar_default.png)
After having tested insertion, lookup, table walk and removal, spawn a number of threads running operations on the same rhashtable. Each of them will: 1) insert it's own set of objects, 2) lookup every successfully inserted object and finally 3) remove objects in several rounds until all of them have been removed, making sure the remaining ones are still found after each round. This should put a good amount of load onto the system and due to synchronising thread startup via two semaphores also extensive concurrent table access. The default number of ten threads returned within half a second on my local VM with two cores. Running 200 threads took about four seconds. If slow systems suffer too much from this though, the default could be lowered or even set to zero so this extended test does not run at all by default. Signed-off-by: Phil Sutter <phil@nwl.cc> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
406 lines
9.7 KiB
C
406 lines
9.7 KiB
C
/*
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* Resizable, Scalable, Concurrent Hash Table
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*
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* Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch>
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* Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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/**************************************************************************
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* Self Test
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**************************************************************************/
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#include <linux/init.h>
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#include <linux/jhash.h>
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#include <linux/kernel.h>
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#include <linux/kthread.h>
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#include <linux/module.h>
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#include <linux/rcupdate.h>
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#include <linux/rhashtable.h>
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#include <linux/semaphore.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/vmalloc.h>
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#define MAX_ENTRIES 1000000
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#define TEST_INSERT_FAIL INT_MAX
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static int entries = 50000;
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module_param(entries, int, 0);
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MODULE_PARM_DESC(entries, "Number of entries to add (default: 50000)");
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static int runs = 4;
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module_param(runs, int, 0);
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MODULE_PARM_DESC(runs, "Number of test runs per variant (default: 4)");
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static int max_size = 65536;
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module_param(max_size, int, 0);
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MODULE_PARM_DESC(runs, "Maximum table size (default: 65536)");
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static bool shrinking = false;
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module_param(shrinking, bool, 0);
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MODULE_PARM_DESC(shrinking, "Enable automatic shrinking (default: off)");
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static int size = 8;
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module_param(size, int, 0);
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MODULE_PARM_DESC(size, "Initial size hint of table (default: 8)");
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static int tcount = 10;
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module_param(tcount, int, 0);
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MODULE_PARM_DESC(tcount, "Number of threads to spawn (default: 10)");
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struct test_obj {
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int value;
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struct rhash_head node;
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};
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struct thread_data {
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int id;
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struct task_struct *task;
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struct test_obj *objs;
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};
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static struct test_obj array[MAX_ENTRIES];
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static struct rhashtable_params test_rht_params = {
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.head_offset = offsetof(struct test_obj, node),
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.key_offset = offsetof(struct test_obj, value),
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.key_len = sizeof(int),
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.hashfn = jhash,
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.nulls_base = (3U << RHT_BASE_SHIFT),
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};
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static struct semaphore prestart_sem;
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static struct semaphore startup_sem = __SEMAPHORE_INITIALIZER(startup_sem, 0);
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static int __init test_rht_lookup(struct rhashtable *ht)
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{
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unsigned int i;
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for (i = 0; i < entries * 2; i++) {
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struct test_obj *obj;
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bool expected = !(i % 2);
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u32 key = i;
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if (array[i / 2].value == TEST_INSERT_FAIL)
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expected = false;
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obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
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if (expected && !obj) {
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pr_warn("Test failed: Could not find key %u\n", key);
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return -ENOENT;
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} else if (!expected && obj) {
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pr_warn("Test failed: Unexpected entry found for key %u\n",
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key);
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return -EEXIST;
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} else if (expected && obj) {
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if (obj->value != i) {
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pr_warn("Test failed: Lookup value mismatch %u!=%u\n",
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obj->value, i);
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return -EINVAL;
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}
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}
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cond_resched_rcu();
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}
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return 0;
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}
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static void test_bucket_stats(struct rhashtable *ht)
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{
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unsigned int err, total = 0, chain_len = 0;
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struct rhashtable_iter hti;
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struct rhash_head *pos;
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err = rhashtable_walk_init(ht, &hti);
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if (err) {
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pr_warn("Test failed: allocation error");
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return;
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}
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err = rhashtable_walk_start(&hti);
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if (err && err != -EAGAIN) {
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pr_warn("Test failed: iterator failed: %d\n", err);
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return;
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}
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while ((pos = rhashtable_walk_next(&hti))) {
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if (PTR_ERR(pos) == -EAGAIN) {
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pr_info("Info: encountered resize\n");
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chain_len++;
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continue;
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} else if (IS_ERR(pos)) {
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pr_warn("Test failed: rhashtable_walk_next() error: %ld\n",
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PTR_ERR(pos));
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break;
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}
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total++;
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}
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rhashtable_walk_stop(&hti);
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rhashtable_walk_exit(&hti);
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pr_info(" Traversal complete: counted=%u, nelems=%u, entries=%d, table-jumps=%u\n",
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total, atomic_read(&ht->nelems), entries, chain_len);
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if (total != atomic_read(&ht->nelems) || total != entries)
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pr_warn("Test failed: Total count mismatch ^^^");
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}
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static s64 __init test_rhashtable(struct rhashtable *ht)
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{
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struct test_obj *obj;
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int err;
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unsigned int i, insert_fails = 0;
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s64 start, end;
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/*
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* Insertion Test:
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* Insert entries into table with all keys even numbers
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*/
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pr_info(" Adding %d keys\n", entries);
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start = ktime_get_ns();
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for (i = 0; i < entries; i++) {
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struct test_obj *obj = &array[i];
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obj->value = i * 2;
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err = rhashtable_insert_fast(ht, &obj->node, test_rht_params);
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if (err == -ENOMEM || err == -EBUSY) {
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/* Mark failed inserts but continue */
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obj->value = TEST_INSERT_FAIL;
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insert_fails++;
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} else if (err) {
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return err;
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}
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cond_resched();
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}
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if (insert_fails)
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pr_info(" %u insertions failed due to memory pressure\n",
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insert_fails);
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test_bucket_stats(ht);
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rcu_read_lock();
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test_rht_lookup(ht);
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rcu_read_unlock();
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test_bucket_stats(ht);
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pr_info(" Deleting %d keys\n", entries);
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for (i = 0; i < entries; i++) {
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u32 key = i * 2;
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if (array[i].value != TEST_INSERT_FAIL) {
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obj = rhashtable_lookup_fast(ht, &key, test_rht_params);
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BUG_ON(!obj);
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rhashtable_remove_fast(ht, &obj->node, test_rht_params);
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}
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cond_resched();
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}
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end = ktime_get_ns();
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pr_info(" Duration of test: %lld ns\n", end - start);
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return end - start;
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}
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static struct rhashtable ht;
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static int thread_lookup_test(struct thread_data *tdata)
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{
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int i, err = 0;
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for (i = 0; i < entries; i++) {
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struct test_obj *obj;
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int key = (tdata->id << 16) | i;
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obj = rhashtable_lookup_fast(&ht, &key, test_rht_params);
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if (obj && (tdata->objs[i].value == TEST_INSERT_FAIL)) {
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pr_err(" found unexpected object %d\n", key);
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err++;
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} else if (!obj && (tdata->objs[i].value != TEST_INSERT_FAIL)) {
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pr_err(" object %d not found!\n", key);
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err++;
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} else if (obj && (obj->value != key)) {
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pr_err(" wrong object returned (got %d, expected %d)\n",
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obj->value, key);
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err++;
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}
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}
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return err;
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}
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static int threadfunc(void *data)
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{
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int i, step, err = 0, insert_fails = 0;
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struct thread_data *tdata = data;
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up(&prestart_sem);
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if (down_interruptible(&startup_sem))
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pr_err(" thread[%d]: down_interruptible failed\n", tdata->id);
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for (i = 0; i < entries; i++) {
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tdata->objs[i].value = (tdata->id << 16) | i;
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err = rhashtable_insert_fast(&ht, &tdata->objs[i].node,
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test_rht_params);
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if (err == -ENOMEM || err == -EBUSY) {
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tdata->objs[i].value = TEST_INSERT_FAIL;
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insert_fails++;
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} else if (err) {
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pr_err(" thread[%d]: rhashtable_insert_fast failed\n",
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tdata->id);
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goto out;
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}
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}
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if (insert_fails)
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pr_info(" thread[%d]: %d insert failures\n",
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tdata->id, insert_fails);
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err = thread_lookup_test(tdata);
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if (err) {
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pr_err(" thread[%d]: rhashtable_lookup_test failed\n",
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tdata->id);
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goto out;
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}
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for (step = 10; step > 0; step--) {
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for (i = 0; i < entries; i += step) {
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if (tdata->objs[i].value == TEST_INSERT_FAIL)
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continue;
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err = rhashtable_remove_fast(&ht, &tdata->objs[i].node,
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test_rht_params);
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if (err) {
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pr_err(" thread[%d]: rhashtable_remove_fast failed\n",
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tdata->id);
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goto out;
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}
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tdata->objs[i].value = TEST_INSERT_FAIL;
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}
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err = thread_lookup_test(tdata);
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if (err) {
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pr_err(" thread[%d]: rhashtable_lookup_test (2) failed\n",
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tdata->id);
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goto out;
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}
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}
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out:
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while (!kthread_should_stop()) {
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set_current_state(TASK_INTERRUPTIBLE);
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schedule();
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}
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return err;
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}
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static int __init test_rht_init(void)
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{
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int i, err, started_threads = 0, failed_threads = 0;
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u64 total_time = 0;
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struct thread_data *tdata;
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struct test_obj *objs;
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entries = min(entries, MAX_ENTRIES);
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test_rht_params.automatic_shrinking = shrinking;
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test_rht_params.max_size = max_size;
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test_rht_params.nelem_hint = size;
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pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
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size, max_size, shrinking);
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for (i = 0; i < runs; i++) {
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s64 time;
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pr_info("Test %02d:\n", i);
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memset(&array, 0, sizeof(array));
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err = rhashtable_init(&ht, &test_rht_params);
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if (err < 0) {
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pr_warn("Test failed: Unable to initialize hashtable: %d\n",
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err);
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continue;
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}
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time = test_rhashtable(&ht);
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rhashtable_destroy(&ht);
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if (time < 0) {
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pr_warn("Test failed: return code %lld\n", time);
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return -EINVAL;
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}
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total_time += time;
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}
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do_div(total_time, runs);
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pr_info("Average test time: %llu\n", total_time);
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if (!tcount)
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return 0;
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pr_info("Testing concurrent rhashtable access from %d threads\n",
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tcount);
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sema_init(&prestart_sem, 1 - tcount);
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tdata = vzalloc(tcount * sizeof(struct thread_data));
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if (!tdata)
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return -ENOMEM;
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objs = vzalloc(tcount * entries * sizeof(struct test_obj));
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if (!objs) {
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vfree(tdata);
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return -ENOMEM;
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}
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err = rhashtable_init(&ht, &test_rht_params);
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if (err < 0) {
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pr_warn("Test failed: Unable to initialize hashtable: %d\n",
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err);
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vfree(tdata);
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vfree(objs);
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return -EINVAL;
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}
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for (i = 0; i < tcount; i++) {
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tdata[i].id = i;
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tdata[i].objs = objs + i * entries;
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tdata[i].task = kthread_run(threadfunc, &tdata[i],
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"rhashtable_thrad[%d]", i);
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if (IS_ERR(tdata[i].task))
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pr_err(" kthread_run failed for thread %d\n", i);
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else
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started_threads++;
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}
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if (down_interruptible(&prestart_sem))
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pr_err(" down interruptible failed\n");
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for (i = 0; i < tcount; i++)
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up(&startup_sem);
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for (i = 0; i < tcount; i++) {
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if (IS_ERR(tdata[i].task))
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continue;
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if ((err = kthread_stop(tdata[i].task))) {
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pr_warn("Test failed: thread %d returned: %d\n",
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i, err);
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failed_threads++;
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}
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}
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pr_info("Started %d threads, %d failed\n",
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started_threads, failed_threads);
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rhashtable_destroy(&ht);
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vfree(tdata);
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vfree(objs);
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return 0;
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}
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static void __exit test_rht_exit(void)
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{
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}
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module_init(test_rht_init);
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module_exit(test_rht_exit);
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MODULE_LICENSE("GPL v2");
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