[dpdk-users] Failing to add entry to hashmap

[Cacheco Gnudu <cacheco@posteo.net>]

Hello everyone,

I'm programming a testbed with DPDK that needs to create a hashmap with
32768 entries and maybe more in the future. To create it, I use
rte_hash_add_key_data() inside a for loop.

I was checking the return value of rte_hash_add_key_data() and whenever
it was negative, the program would terminate with rte_exit(). Every time
it added the 32224th entry it would terminate with -ENOSPC. I replaced
rte_exit() to a simple printf() to let me know it received a negative
value from rte_hash_add_key_data(), but would keep adding new entries
and it does. It alternatively succeeds and fails, and when it fails its
always with -ENOSPC. At the end only 32640 entries are added.

I pasted the hash creation code and the end of the execution output as
well.

--- code starts here ---
/* ... */
#define MAX_IPS         32768
/* ... */
int err = 0;
static struct rte_hash *PPVE_HASHMAP;
struct rte_hash_parameters params = { 0 };
params.name = "ip_filter_hashmap";
params.entries = MAX_IPS;
params.key_len = sizeof(uint64_t);
params.hash_func = rte_jhash;
params.hash_func_init_val = 0;
params.socket_id = rte_socket_id();

uint32_t size = rte_hash_count(PPVE_HASHMAP);
printf("%d\n", size);

PPVE_HASHMAP = rte_hash_create(&params);
if (PPVE_HASHMAP == NULL)
     rte_exit(EXIT_DPDK_FAIL,
              "Failed to create hash table, errno = %d\n", rte_errno);
size = rte_hash_count(PPVE_HASHMAP);
printf("%d\n", size);

uint64_t key = 10, value = 0xdead;
for (int i = 0; i < MAX_IPS; i++) {

     err = rte_hash_add_key_data(PPVE_HASHMAP, &key, &value);
     uint32_t size = rte_hash_count(PPVE_HASHMAP);

     printf("%d\n", size);
     if (err < 0)
         rte_exit(EXIT_DPDK_FAIL,
                  "Failed to add entry to hash table, err: %d\n", err);
     key++;
}
/* ... */
--- code ends here ---


--- end of program output starts here ---
32635
32635
Failed to add entry to hash table, err: -28
32636
32637
32638
32639
32639
Failed to add entry to hash table, err: -28
32640
32640
Failed to add entry to hash table, err: -28
32640
Failed to add entry to hash table, err: -28
32640
Failed to add entry to hash table, err: -28
32640
Failed to add entry to hash table, err: -28
32640
Failed to add entry to hash table, err: -28
32640
Failed to add entry to hash table, err: -28
32640
Failed to add entry to hash table, err: -28
32640
Failed to add entry to hash table, err: -28
32640
Failed to add entry to hash table, err: -28
--- end of program output ends here ---


-- 
Sincerely,
Cacheco