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Commit 930d3142 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'rhashtable-test-enhancements' 



Phil Sutter says:

====================
improve fault-tolerance of rhashtable runtime-test

The following series aims to improve lib/test_rhashtable in different
situations:

Patch 1 allows the kernel to reschedule so the test does not block too
        long on slow systems.
Patch 2 fixes behaviour under pressure, retrying inserts in non-permanent
        error case (-EBUSY).
Patch 3 auto-adjusts the upper table size limit according to the number
        of threads (in concurrency test). In fact, the current default is
	already too small.
Patch 4 makes it possible to retry inserts even in supposedly permanent
        error case (-ENOMEM) to expose rhashtable's remaining problem of
	-ENOMEM being not as permanent as it is expected to be.

Changes since v1:
- Introduce insert_retry() which is then used in single-threaded test as
  well.
- Do not retry inserts by default if -ENOMEM was returned.
- Rename the retry counter to be a bit more verbose about what it
  contains.
- Add patch 4 as a debugging aid.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 3d40e443 d662e037

lib/test_rhashtable.c

+50 −26
Original line number Diff line number Diff line
@@ -36,9 +36,9 @@ 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;

static int max_size = 0;

module_param(max_size, int, 0);

MODULE_PARM_DESC(runs, "Maximum table size (default: 65536)");

MODULE_PARM_DESC(runs, "Maximum table size (default: calculated)");



static bool shrinking = false;

module_param(shrinking, bool, 0);
@@ -52,6 +52,10 @@ static int tcount = 10; 
module_param(tcount, int, 0);

MODULE_PARM_DESC(tcount, "Number of threads to spawn (default: 10)");



static bool enomem_retry = false;

module_param(enomem_retry, bool, 0);

MODULE_PARM_DESC(enomem_retry, "Retry insert even if -ENOMEM was returned (default: off)");



struct test_obj {

	int			value;

	struct rhash_head	node;
@@ -76,6 +80,28 @@ static struct rhashtable_params test_rht_params = { 
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, enomem_retries = 0;



	do {

		retries++;

		cond_resched();

		err = rhashtable_insert_fast(ht, obj, params);

		if (err == -ENOMEM && enomem_retry) {

			enomem_retries++;

			err = -EBUSY;

		}

	} while (err == -EBUSY);



	if (enomem_retries)

		pr_info(" %u insertions retried after -ENOMEM\n",

			enomem_retries);



	return err ? : retries;

}



static int __init test_rht_lookup(struct rhashtable *ht)

{

	unsigned int i;
@@ -157,7 +183,7 @@ static s64 __init test_rhashtable(struct rhashtable *ht) 
{

	struct test_obj *obj;

	int err;

	unsigned int i, insert_fails = 0;

	unsigned int i, insert_retries = 0;

	s64 start, end;



	/*
@@ -170,22 +196,16 @@ static s64 __init test_rhashtable(struct rhashtable *ht) 
		struct test_obj *obj = &array[i];



		obj->value = i * 2;



		err = rhashtable_insert_fast(ht, &obj->node, test_rht_params);

		if (err == -ENOMEM || err == -EBUSY) {

			/* Mark failed inserts but continue */

			obj->value = TEST_INSERT_FAIL;

			insert_fails++;

		} else if (err) {

		err = insert_retry(ht, &obj->node, test_rht_params);

		if (err > 0)

			insert_retries += err;

		else if (err)

			return err;

	}



		cond_resched();

	}



	if (insert_fails)

		pr_info("  %u insertions failed due to memory pressure\n",

			insert_fails);

	if (insert_retries)

		pr_info("  %u insertions retried due to memory pressure\n",

			insert_retries);



	test_bucket_stats(ht);

	rcu_read_lock();
@@ -236,13 +256,15 @@ static int thread_lookup_test(struct thread_data *tdata) 
			       obj->value, key);

			err++;

		}



		cond_resched();

	}

	return err;

}



static int threadfunc(void *data)

{

	int i, step, err = 0, insert_fails = 0;

	int i, step, err = 0, insert_retries = 0;

	struct thread_data *tdata = data;



	up(&prestart_sem);
@@ -251,20 +273,18 @@ static int threadfunc(void *data) 


	for (i = 0; i < entries; i++) {

		tdata->objs[i].value = (tdata->id << 16) | i;

		err = rhashtable_insert_fast(&ht, &tdata->objs[i].node,

		                             test_rht_params);

		if (err == -ENOMEM || err == -EBUSY) {

			tdata->objs[i].value = TEST_INSERT_FAIL;

			insert_fails++;

		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_fails)

		pr_info("  thread[%d]: %d insert failures\n",

		        tdata->id, insert_fails);

	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) {
@@ -285,6 +305,8 @@ static int threadfunc(void *data) 
				goto out;

			}

			tdata->objs[i].value = TEST_INSERT_FAIL;



			cond_resched();

		}

		err = thread_lookup_test(tdata);

		if (err) {
@@ -311,7 +333,7 @@ static int __init test_rht_init(void) 
	entries = min(entries, MAX_ENTRIES);



	test_rht_params.automatic_shrinking = shrinking;

	test_rht_params.max_size = max_size;

	test_rht_params.max_size = max_size ? : roundup_pow_of_two(entries);

	test_rht_params.nelem_hint = size;



	pr_info("Running rhashtable test nelem=%d, max_size=%d, shrinking=%d\n",
@@ -357,6 +379,8 @@ static int __init test_rht_init(void) 
		return -ENOMEM;

	}



	test_rht_params.max_size = max_size ? :

	                           roundup_pow_of_two(tcount * entries);

	err = rhashtable_init(&ht, &test_rht_params);

	if (err < 0) {

		pr_warn("Test failed: Unable to initialize hashtable: %d\n",