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Merge branch 'rhashtable-test-enhancements'

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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: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2015-11-23 12:36:09 -05:00
commit 930d3142b8
1 changed files with 50 additions and 26 deletions
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76
lib/test_rhashtable.c
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@ -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",