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>

diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
index 63654e359256cebf987e153e545ca2f29b0889e8..cfc3440f17e7b16272555df0c310eb6a4743b867 100644 (file)
--- a/lib/test_rhashtable.c
+++ b/lib/test_rhashtable.c
@@ -76,6 +76,20 @@ 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;
+
+       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;
@@ -157,7 +171,7 @@ 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 +184,16 @@ 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();
@@ -244,7 +252,7 @@ static int thread_lookup_test(struct thread_data *tdata)
 
 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);
@@ -253,21 +261,18 @@ static int threadfunc(void *data)
 
        for (i = 0; i < entries; i++) {
                tdata->objs[i].value = (tdata->id << 16) | i;
-               cond_resched();
-               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) {