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-rw-r--r--lib/librte_hash/rte_cuckoo_hash.c417
-rw-r--r--lib/librte_hash/rte_cuckoo_hash.h5
-rw-r--r--lib/librte_hash/rte_hash.h47
3 files changed, 351 insertions, 118 deletions
diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index d79ba68..0648a22 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -1,5 +1,6 @@
/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2010-2016 Intel Corporation
+ * Copyright(c) 2018 Arm Limited
*/
#include <string.h>
@@ -141,6 +142,8 @@ rte_hash_create(const struct rte_hash_parameters *params)
unsigned int readwrite_concur_support = 0;
unsigned int writer_takes_lock = 0;
unsigned int no_free_on_del = 0;
+ uint32_t *tbl_chng_cnt = NULL;
+ unsigned int readwrite_concur_lf_support = 0;
rte_hash_function default_hash_func = (rte_hash_function)rte_jhash;
@@ -160,6 +163,24 @@ rte_hash_create(const struct rte_hash_parameters *params)
return NULL;
}
+ /* Validate correct usage of extra options */
+ if ((params->extra_flag & RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY) &&
+ (params->extra_flag & RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF)) {
+ rte_errno = EINVAL;
+ RTE_LOG(ERR, HASH, "rte_hash_create: choose rw concurrency or "
+ "rw concurrency lock free\n");
+ return NULL;
+ }
+
+ if ((params->extra_flag & RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF) &&
+ (params->extra_flag & RTE_HASH_EXTRA_FLAGS_EXT_TABLE)) {
+ rte_errno = EINVAL;
+ RTE_LOG(ERR, HASH, "rte_hash_create: extendable bucket "
+ "feature not supported with rw concurrency "
+ "lock free\n");
+ return NULL;
+ }
+
/* Check extra flags field to check extra options. */
if (params->extra_flag & RTE_HASH_EXTRA_FLAGS_TRANS_MEM_SUPPORT)
hw_trans_mem_support = 1;
@@ -180,6 +201,12 @@ rte_hash_create(const struct rte_hash_parameters *params)
if (params->extra_flag & RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL)
no_free_on_del = 1;
+ if (params->extra_flag & RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF) {
+ readwrite_concur_lf_support = 1;
+ /* Enable not freeing internal memory/index on delete */
+ no_free_on_del = 1;
+ }
+
/* Store all keys and leave the first entry as a dummy entry for lookup_bulk */
if (use_local_cache)
/*
@@ -292,6 +319,14 @@ rte_hash_create(const struct rte_hash_parameters *params)
goto err_unlock;
}
+ tbl_chng_cnt = rte_zmalloc_socket(NULL, sizeof(uint32_t),
+ RTE_CACHE_LINE_SIZE, params->socket_id);
+
+ if (tbl_chng_cnt == NULL) {
+ RTE_LOG(ERR, HASH, "memory allocation failed\n");
+ goto err_unlock;
+ }
+
/*
* If x86 architecture is used, select appropriate compare function,
* which may use x86 intrinsics, otherwise use memcmp
@@ -360,12 +395,15 @@ rte_hash_create(const struct rte_hash_parameters *params)
default_hash_func : params->hash_func;
h->key_store = k;
h->free_slots = r;
+ h->tbl_chng_cnt = tbl_chng_cnt;
+ *h->tbl_chng_cnt = 0;
h->hw_trans_mem_support = hw_trans_mem_support;
h->use_local_cache = use_local_cache;
h->readwrite_concur_support = readwrite_concur_support;
h->ext_table_support = ext_table_support;
h->writer_takes_lock = writer_takes_lock;
h->no_free_on_del = no_free_on_del;
+ h->readwrite_concur_lf_support = readwrite_concur_lf_support;
#if defined(RTE_ARCH_X86)
if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE2))
@@ -406,6 +444,7 @@ err:
rte_free(buckets);
rte_free(buckets_ext);
rte_free(k);
+ rte_free(tbl_chng_cnt);
return NULL;
}
@@ -446,6 +485,7 @@ rte_hash_free(struct rte_hash *h)
rte_free(h->key_store);
rte_free(h->buckets);
rte_free(h->buckets_ext);
+ rte_free(h->tbl_chng_cnt);
rte_free(h);
rte_free(te);
}
@@ -530,6 +570,7 @@ rte_hash_reset(struct rte_hash *h)
__hash_rw_writer_lock(h);
memset(h->buckets, 0, h->num_buckets * sizeof(struct rte_hash_bucket));
memset(h->key_store, 0, h->key_entry_size * (h->entries + 1));
+ *h->tbl_chng_cnt = 0;
/* clear the free ring */
while (rte_ring_dequeue(h->free_slots, &ptr) == 0)
@@ -585,7 +626,9 @@ enqueue_slot_back(const struct rte_hash *h,
rte_ring_sp_enqueue(h->free_slots, slot_id);
}
-/* Search a key from bucket and update its data */
+/* Search a key from bucket and update its data.
+ * Writer holds the lock before calling this.
+ */
static inline int32_t
search_and_update(const struct rte_hash *h, void *data, const void *key,
struct rte_hash_bucket *bkt, uint16_t sig)
@@ -598,8 +641,13 @@ search_and_update(const struct rte_hash *h, void *data, const void *key,
k = (struct rte_hash_key *) ((char *)keys +
bkt->key_idx[i] * h->key_entry_size);
if (rte_hash_cmp_eq(key, k->key, h) == 0) {
- /* Update data */
- k->pdata = data;
+ /* 'pdata' acts as the synchronization point
+ * when an existing hash entry is updated.
+ * Key is not updated in this case.
+ */
+ __atomic_store_n(&k->pdata,
+ data,
+ __ATOMIC_RELEASE);
/*
* Return index where key is stored,
* subtracting the first dummy index
@@ -655,7 +703,15 @@ rte_hash_cuckoo_insert_mw(const struct rte_hash *h,
/* Check if slot is available */
if (likely(prim_bkt->key_idx[i] == EMPTY_SLOT)) {
prim_bkt->sig_current[i] = sig;
- prim_bkt->key_idx[i] = new_idx;
+ /* Key can be of arbitrary length, so it is
+ * not possible to store it atomically.
+ * Hence the new key element's memory stores
+ * (key as well as data) should be complete
+ * before it is referenced.
+ */
+ __atomic_store_n(&prim_bkt->key_idx[i],
+ new_idx,
+ __ATOMIC_RELEASE);
break;
}
}
@@ -728,27 +784,66 @@ rte_hash_cuckoo_move_insert_mw(const struct rte_hash *h,
if (unlikely(&h->buckets[prev_alt_bkt_idx]
!= curr_bkt)) {
/* revert it to empty, otherwise duplicated keys */
- curr_bkt->key_idx[curr_slot] = EMPTY_SLOT;
+ __atomic_store_n(&curr_bkt->key_idx[curr_slot],
+ EMPTY_SLOT,
+ __ATOMIC_RELEASE);
__hash_rw_writer_unlock(h);
return -1;
}
+ if (h->readwrite_concur_lf_support) {
+ /* Inform the previous move. The current move need
+ * not be informed now as the current bucket entry
+ * is present in both primary and secondary.
+ * Since there is one writer, load acquires on
+ * tbl_chng_cnt are not required.
+ */
+ __atomic_store_n(h->tbl_chng_cnt,
+ *h->tbl_chng_cnt + 1,
+ __ATOMIC_RELEASE);
+ /* The stores to sig_alt and sig_current should not
+ * move above the store to tbl_chng_cnt.
+ */
+ __atomic_thread_fence(__ATOMIC_RELEASE);
+ }
+
/* Need to swap current/alt sig to allow later
* Cuckoo insert to move elements back to its
* primary bucket if available
*/
curr_bkt->sig_current[curr_slot] =
prev_bkt->sig_current[prev_slot];
- curr_bkt->key_idx[curr_slot] =
- prev_bkt->key_idx[prev_slot];
+ /* Release the updated bucket entry */
+ __atomic_store_n(&curr_bkt->key_idx[curr_slot],
+ prev_bkt->key_idx[prev_slot],
+ __ATOMIC_RELEASE);
curr_slot = prev_slot;
curr_node = prev_node;
curr_bkt = curr_node->bkt;
}
+ if (h->readwrite_concur_lf_support) {
+ /* Inform the previous move. The current move need
+ * not be informed now as the current bucket entry
+ * is present in both primary and secondary.
+ * Since there is one writer, load acquires on
+ * tbl_chng_cnt are not required.
+ */
+ __atomic_store_n(h->tbl_chng_cnt,
+ *h->tbl_chng_cnt + 1,
+ __ATOMIC_RELEASE);
+ /* The stores to sig_alt and sig_current should not
+ * move above the store to tbl_chng_cnt.
+ */
+ __atomic_thread_fence(__ATOMIC_RELEASE);
+ }
+
curr_bkt->sig_current[curr_slot] = sig;
- curr_bkt->key_idx[curr_slot] = new_idx;
+ /* Release the new bucket entry */
+ __atomic_store_n(&curr_bkt->key_idx[curr_slot],
+ new_idx,
+ __ATOMIC_RELEASE);
__hash_rw_writer_unlock(h);
@@ -889,8 +984,15 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
new_idx = (uint32_t)((uintptr_t) slot_id);
/* Copy key */
rte_memcpy(new_k->key, key, h->key_len);
- new_k->pdata = data;
-
+ /* Key can be of arbitrary length, so it is not possible to store
+ * it atomically. Hence the new key element's memory stores
+ * (key as well as data) should be complete before it is referenced.
+ * 'pdata' acts as the synchronization point when an existing hash
+ * entry is updated.
+ */
+ __atomic_store_n(&new_k->pdata,
+ data,
+ __ATOMIC_RELEASE);
/* Find an empty slot and insert */
ret = rte_hash_cuckoo_insert_mw(h, prim_bkt, sec_bkt, key, data,
@@ -1034,21 +1136,27 @@ search_one_bucket(const struct rte_hash *h, const void *key, uint16_t sig,
void **data, const struct rte_hash_bucket *bkt)
{
int i;
+ uint32_t key_idx;
+ void *pdata;
struct rte_hash_key *k, *keys = h->key_store;
for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
- if (bkt->sig_current[i] == sig &&
- bkt->key_idx[i] != EMPTY_SLOT) {
+ key_idx = __atomic_load_n(&bkt->key_idx[i],
+ __ATOMIC_ACQUIRE);
+ if (bkt->sig_current[i] == sig && key_idx != EMPTY_SLOT) {
k = (struct rte_hash_key *) ((char *)keys +
- bkt->key_idx[i] * h->key_entry_size);
+ key_idx * h->key_entry_size);
+ pdata = __atomic_load_n(&k->pdata,
+ __ATOMIC_ACQUIRE);
+
if (rte_hash_cmp_eq(key, k->key, h) == 0) {
if (data != NULL)
- *data = k->pdata;
+ *data = pdata;
/*
* Return index where key is stored,
* subtracting the first dummy index
*/
- return bkt->key_idx[i] - 1;
+ return key_idx - 1;
}
}
}
@@ -1061,34 +1169,62 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
{
uint32_t prim_bucket_idx, sec_bucket_idx;
struct rte_hash_bucket *bkt, *cur_bkt;
+ uint32_t cnt_b, cnt_a;
int ret;
uint16_t short_sig;
short_sig = get_short_sig(sig);
prim_bucket_idx = get_prim_bucket_index(h, sig);
sec_bucket_idx = get_alt_bucket_index(h, prim_bucket_idx, short_sig);
- bkt = &h->buckets[prim_bucket_idx];
__hash_rw_reader_lock(h);
- /* Check if key is in primary location */
- ret = search_one_bucket(h, key, short_sig, data, bkt);
- if (ret != -1) {
- __hash_rw_reader_unlock(h);
- return ret;
- }
- /* Calculate secondary hash */
- bkt = &h->buckets[sec_bucket_idx];
+ do {
+ /* Load the table change counter before the lookup
+ * starts. Acquire semantics will make sure that
+ * loads in search_one_bucket are not hoisted.
+ */
+ cnt_b = __atomic_load_n(h->tbl_chng_cnt,
+ __ATOMIC_ACQUIRE);
- /* Check if key is in secondary location */
- FOR_EACH_BUCKET(cur_bkt, bkt) {
- ret = search_one_bucket(h, key, short_sig, data, cur_bkt);
+ /* Check if key is in primary location */
+ bkt = &h->buckets[prim_bucket_idx];
+ ret = search_one_bucket(h, key, short_sig, data, bkt);
if (ret != -1) {
__hash_rw_reader_unlock(h);
return ret;
}
- }
+ /* Calculate secondary hash */
+ bkt = &h->buckets[sec_bucket_idx];
+
+ /* Check if key is in secondary location */
+ FOR_EACH_BUCKET(cur_bkt, bkt) {
+ ret = search_one_bucket(h, key, short_sig,
+ data, cur_bkt);
+ if (ret != -1) {
+ __hash_rw_reader_unlock(h);
+ return ret;
+ }
+ }
+
+ /* The loads of sig_current in search_one_bucket
+ * should not move below the load from tbl_chng_cnt.
+ */
+ __atomic_thread_fence(__ATOMIC_ACQUIRE);
+ /* Re-read the table change counter to check if the
+ * table has changed during search. If yes, re-do
+ * the search.
+ * This load should not get hoisted. The load
+ * acquires on cnt_b, key index in primary bucket
+ * and key index in secondary bucket will make sure
+ * that it does not get hoisted.
+ */
+ cnt_a = __atomic_load_n(h->tbl_chng_cnt,
+ __ATOMIC_ACQUIRE);
+ } while (cnt_b != cnt_a);
+
__hash_rw_reader_unlock(h);
+
return -ENOENT;
}
@@ -1173,21 +1309,25 @@ __rte_hash_compact_ll(struct rte_hash_bucket *cur_bkt, int pos) {
}
}
-/* Search one bucket and remove the matched key */
+/* Search one bucket and remove the matched key.
+ * Writer is expected to hold the lock while calling this
+ * function.
+ */
static inline int32_t
search_and_remove(const struct rte_hash *h, const void *key,
struct rte_hash_bucket *bkt, uint16_t sig, int *pos)
{
struct rte_hash_key *k, *keys = h->key_store;
unsigned int i;
- int32_t ret;
+ uint32_t key_idx;
/* Check if key is in bucket */
for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
- if (bkt->sig_current[i] == sig &&
- bkt->key_idx[i] != EMPTY_SLOT) {
+ key_idx = __atomic_load_n(&bkt->key_idx[i],
+ __ATOMIC_ACQUIRE);
+ if (bkt->sig_current[i] == sig && key_idx != EMPTY_SLOT) {
k = (struct rte_hash_key *) ((char *)keys +
- bkt->key_idx[i] * h->key_entry_size);
+ key_idx * h->key_entry_size);
if (rte_hash_cmp_eq(key, k->key, h) == 0) {
bkt->sig_current[i] = NULL_SIGNATURE;
/* Free the key store index if
@@ -1196,13 +1336,16 @@ search_and_remove(const struct rte_hash *h, const void *key,
if (!h->no_free_on_del)
remove_entry(h, bkt, i);
- /* Return index where key is stored,
+ __atomic_store_n(&bkt->key_idx[i],
+ EMPTY_SLOT,
+ __ATOMIC_RELEASE);
+
+ *pos = i;
+ /*
+ * Return index where key is stored,
* subtracting the first dummy index
*/
- ret = bkt->key_idx[i] - 1;
- bkt->key_idx[i] = EMPTY_SLOT;
- *pos = i;
- return ret;
+ return key_idx - 1;
}
}
}
@@ -1402,6 +1545,8 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
uint32_t prim_hitmask[RTE_HASH_LOOKUP_BULK_MAX] = {0};
uint32_t sec_hitmask[RTE_HASH_LOOKUP_BULK_MAX] = {0};
struct rte_hash_bucket *cur_bkt, *next_bkt;
+ void *pdata[RTE_HASH_LOOKUP_BULK_MAX];
+ uint32_t cnt_b, cnt_a;
/* Prefetch first keys */
for (i = 0; i < PREFETCH_OFFSET && i < num_keys; i++)
@@ -1443,91 +1588,138 @@ __rte_hash_lookup_bulk(const struct rte_hash *h, const void **keys,
}
__hash_rw_reader_lock(h);
- /* Compare signatures and prefetch key slot of first hit */
- for (i = 0; i < num_keys; i++) {
- compare_signatures(&prim_hitmask[i], &sec_hitmask[i],
+ do {
+ /* Load the table change counter before the lookup
+ * starts. Acquire semantics will make sure that
+ * loads in compare_signatures are not hoisted.
+ */
+ cnt_b = __atomic_load_n(h->tbl_chng_cnt,
+ __ATOMIC_ACQUIRE);
+
+ /* Compare signatures and prefetch key slot of first hit */
+ for (i = 0; i < num_keys; i++) {
+ compare_signatures(&prim_hitmask[i], &sec_hitmask[i],
primary_bkt[i], secondary_bkt[i],
sig[i], h->sig_cmp_fn);
- if (prim_hitmask[i]) {
- uint32_t first_hit =
- __builtin_ctzl(prim_hitmask[i]) >> 1;
- uint32_t key_idx = primary_bkt[i]->key_idx[first_hit];
- const struct rte_hash_key *key_slot =
- (const struct rte_hash_key *)(
- (const char *)h->key_store +
- key_idx * h->key_entry_size);
- rte_prefetch0(key_slot);
- continue;
- }
-
- if (sec_hitmask[i]) {
- uint32_t first_hit =
- __builtin_ctzl(sec_hitmask[i]) >> 1;
- uint32_t key_idx = secondary_bkt[i]->key_idx[first_hit];
- const struct rte_hash_key *key_slot =
- (const struct rte_hash_key *)(
- (const char *)h->key_store +
- key_idx * h->key_entry_size);
- rte_prefetch0(key_slot);
- }
- }
-
- /* Compare keys, first hits in primary first */
- for (i = 0; i < num_keys; i++) {
- positions[i] = -ENOENT;
- while (prim_hitmask[i]) {
- uint32_t hit_index =
- __builtin_ctzl(prim_hitmask[i]) >> 1;
-
- uint32_t key_idx = primary_bkt[i]->key_idx[hit_index];
- const struct rte_hash_key *key_slot =
- (const struct rte_hash_key *)(
- (const char *)h->key_store +
- key_idx * h->key_entry_size);
- /*
- * If key index is 0, do not compare key,
- * as it is checking the dummy slot
- */
- if (!!key_idx & !rte_hash_cmp_eq(key_slot->key, keys[i], h)) {
- if (data != NULL)
- data[i] = key_slot->pdata;
+ if (prim_hitmask[i]) {
+ uint32_t first_hit =
+ __builtin_ctzl(prim_hitmask[i])
+ >> 1;
+ uint32_t key_idx =
+ primary_bkt[i]->key_idx[first_hit];
+ const struct rte_hash_key *key_slot =
+ (const struct rte_hash_key *)(
+ (const char *)h->key_store +
+ key_idx * h->key_entry_size);
+ rte_prefetch0(key_slot);
+ continue;
+ }
- hits |= 1ULL << i;
- positions[i] = key_idx - 1;
- goto next_key;
+ if (sec_hitmask[i]) {
+ uint32_t first_hit =
+ __builtin_ctzl(sec_hitmask[i])
+ >> 1;
+ uint32_t key_idx =
+ secondary_bkt[i]->key_idx[first_hit];
+ const struct rte_hash_key *key_slot =
+ (const struct rte_hash_key *)(
+ (const char *)h->key_store +
+ key_idx * h->key_entry_size);
+ rte_prefetch0(key_slot);
}
- prim_hitmask[i] &= ~(3ULL << (hit_index << 1));
}
- while (sec_hitmask[i]) {
- uint32_t hit_index =
- __builtin_ctzl(sec_hitmask[i]) >> 1;
-
- uint32_t key_idx = secondary_bkt[i]->key_idx[hit_index];
- const struct rte_hash_key *key_slot =
- (const struct rte_hash_key *)(
- (const char *)h->key_store +
- key_idx * h->key_entry_size);
- /*
- * If key index is 0, do not compare key,
- * as it is checking the dummy slot
- */
+ /* Compare keys, first hits in primary first */
+ for (i = 0; i < num_keys; i++) {
+ positions[i] = -ENOENT;
+ while (prim_hitmask[i]) {
+ uint32_t hit_index =
+ __builtin_ctzl(prim_hitmask[i])
+ >> 1;
+ uint32_t key_idx =
+ __atomic_load_n(
+ &primary_bkt[i]->key_idx[hit_index],
+ __ATOMIC_ACQUIRE);
+ const struct rte_hash_key *key_slot =
+ (const struct rte_hash_key *)(
+ (const char *)h->key_store +
+ key_idx * h->key_entry_size);
+
+ if (key_idx != EMPTY_SLOT)
+ pdata[i] = __atomic_load_n(
+ &key_slot->pdata,
+ __ATOMIC_ACQUIRE);
+ /*
+ * If key index is 0, do not compare key,
+ * as it is checking the dummy slot
+ */
+ if (!!key_idx &
+ !rte_hash_cmp_eq(
+ key_slot->key, keys[i], h)) {
+ if (data != NULL)
+ data[i] = pdata[i];
+
+ hits |= 1ULL << i;
+ positions[i] = key_idx - 1;
+ goto next_key;
+ }
+ prim_hitmask[i] &= ~(3ULL << (hit_index << 1));
+ }
- if (!!key_idx & !rte_hash_cmp_eq(key_slot->key, keys[i], h)) {
- if (data != NULL)
- data[i] = key_slot->pdata;
+ while (sec_hitmask[i]) {
+ uint32_t hit_index =
+ __builtin_ctzl(sec_hitmask[i])
+ >> 1;
+ uint32_t key_idx =
+ __atomic_load_n(
+ &secondary_bkt[i]->key_idx[hit_index],
+ __ATOMIC_ACQUIRE);
+ const struct rte_hash_key *key_slot =
+ (const struct rte_hash_key *)(
+ (const char *)h->key_store +
+ key_idx * h->key_entry_size);
+
+ if (key_idx != EMPTY_SLOT)
+ pdata[i] = __atomic_load_n(
+ &key_slot->pdata,
+ __ATOMIC_ACQUIRE);
+ /*
+ * If key index is 0, do not compare key,
+ * as it is checking the dummy slot
+ */
- hits |= 1ULL << i;
- positions[i] = key_idx - 1;
- goto next_key;
+ if (!!key_idx &
+ !rte_hash_cmp_eq(
+ key_slot->key, keys[i], h)) {
+ if (data != NULL)
+ data[i] = pdata[i];
+
+ hits |= 1ULL << i;
+ positions[i] = key_idx - 1;
+ goto next_key;
+ }
+ sec_hitmask[i] &= ~(3ULL << (hit_index << 1));
}
- sec_hitmask[i] &= ~(3ULL << (hit_index << 1));
+next_key:
+ continue;
}
-next_key:
- continue;
- }
+ /* The loads of sig_current in compare_signatures
+ * should not move below the load from tbl_chng_cnt.
+ */
+ __atomic_thread_fence(__ATOMIC_ACQUIRE);
+ /* Re-read the table change counter to check if the
+ * table has changed during search. If yes, re-do
+ * the search.
+ * This load should not get hoisted. The load
+ * acquires on cnt_b, primary key index and secondary
+ * key index will make sure that it does not get
+ * hoisted.
+ */
+ cnt_a = __atomic_load_n(h->tbl_chng_cnt,
+ __ATOMIC_ACQUIRE);
+ } while (cnt_b != cnt_a);
/* all found, do not need to go through ext bkt */
if ((hits == ((1ULL << num_keys) - 1)) || !h->ext_table_support) {
@@ -1612,7 +1804,8 @@ rte_hash_iterate(const struct rte_hash *h, const void **key, void **data, uint32
idx = *next % RTE_HASH_BUCKET_ENTRIES;
/* If current position is empty, go to the next one */
- while ((position = h->buckets[bucket_idx].key_idx[idx]) == EMPTY_SLOT) {
+ while ((position = __atomic_load_n(&h->buckets[bucket_idx].key_idx[idx],
+ __ATOMIC_ACQUIRE)) == EMPTY_SLOT) {
(*next)++;
/* End of table */
if (*next == total_entries_main)
diff --git a/lib/librte_hash/rte_cuckoo_hash.h b/lib/librte_hash/rte_cuckoo_hash.h
index 601b2ce..5dfbbc4 100644
--- a/lib/librte_hash/rte_cuckoo_hash.h
+++ b/lib/librte_hash/rte_cuckoo_hash.h
@@ -1,5 +1,6 @@
/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2016 Intel Corporation
+ * Copyright(c) 2018 Arm Limited
*/
/* rte_cuckoo_hash.h
@@ -174,6 +175,8 @@ struct rte_hash {
* free the key index associated with the deleted entry.
* This flag is enabled by default.
*/
+ uint8_t readwrite_concur_lf_support;
+ /**< If read-write concurrency lock free support is enabled */
uint8_t writer_takes_lock;
/**< Indicates if the writer threads need to take lock */
rte_hash_function hash_func; /**< Function used to calculate hash. */
@@ -196,6 +199,8 @@ struct rte_hash {
rte_rwlock_t *readwrite_lock; /**< Read-write lock thread-safety. */
struct rte_hash_bucket *buckets_ext; /**< Extra buckets array */
struct rte_ring *free_ext_bkts; /**< Ring of indexes of free buckets */
+ uint32_t *tbl_chng_cnt;
+ /**< Indicates if the hash table changed from last read. */
} __rte_cache_aligned;
struct queue_node {
diff --git a/lib/librte_hash/rte_hash.h b/lib/librte_hash/rte_hash.h
index dfa542b..c93d1a1 100644
--- a/lib/librte_hash/rte_hash.h
+++ b/lib/librte_hash/rte_hash.h
@@ -44,9 +44,18 @@ extern "C" {
/** Flag to disable freeing of key index on hash delete.
* Refer to rte_hash_del_xxx APIs for more details.
+ * This is enabled by default when RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF
+ * is enabled.
*/
#define RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL 0x10
+/** Flag to support lock free reader writer concurrency. Both single writer
+ * and multi writer use cases are supported.
+ * Currently, extendable bucket table feature is not supported with
+ * this feature.
+ */
+#define RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF 0x20
+
/**
* The type of hash value of a key.
* It should be a value of at least 32bit with fully random pattern.
@@ -132,7 +141,12 @@ void
rte_hash_free(struct rte_hash *h);
/**
- * Reset all hash structure, by zeroing all entries
+ * Reset all hash structure, by zeroing all entries.
+ * When RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled,
+ * it is application's responsibility to make sure that
+ * none of the readers are referencing the hash table
+ * while calling this API.
+ *
* @param h
* Hash table to reset
*/
@@ -156,6 +170,11 @@ rte_hash_count(const struct rte_hash *h);
* and should only be called from one thread by default.
* Thread safety can be enabled by setting flag during
* table creation.
+ * If the key exists already in the table, this API updates its value
+ * with 'data' passed in this API. It is the responsibility of
+ * the application to manage any memory associated with the old value.
+ * The readers might still be using the old value even after this API
+ * has returned.
*
* @param h
* Hash table to add the key to.
@@ -178,6 +197,11 @@ rte_hash_add_key_data(const struct rte_hash *h, const void *key, void *data);
* and should only be called from one thread by default.
* Thread safety can be enabled by setting flag during
* table creation.
+ * If the key exists already in the table, this API updates its value
+ * with 'data' passed in this API. It is the responsibility of
+ * the application to manage any memory associated with the old value.
+ * The readers might still be using the old value even after this API
+ * has returned.
*
* @param h
* Hash table to add the key to.
@@ -243,10 +267,14 @@ rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key, hash_sig_t
* and should only be called from one thread by default.
* Thread safety can be enabled by setting flag during
* table creation.
- * If RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL is enabled,
+ * If RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL or
+ * RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled,
* the key index returned by rte_hash_add_key_xxx APIs will not be
* freed by this API. rte_hash_free_key_with_position API must be called
* additionally to free the index associated with the key.
+ * rte_hash_free_key_with_position API should be called after all
+ * the readers have stopped referencing the entry corresponding to
+ * this key. RCU mechanisms could be used to determine such a state.
*
* @param h
* Hash table to remove the key from.
@@ -268,10 +296,14 @@ rte_hash_del_key(const struct rte_hash *h, const void *key);
* and should only be called from one thread by default.
* Thread safety can be enabled by setting flag during
* table creation.
- * If RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL is enabled,
+ * If RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL or
+ * RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled,
* the key index returned by rte_hash_add_key_xxx APIs will not be
* freed by this API. rte_hash_free_key_with_position API must be called
* additionally to free the index associated with the key.
+ * rte_hash_free_key_with_position API should be called after all
+ * the readers have stopped referencing the entry corresponding to
+ * this key. RCU mechanisms could be used to determine such a state.
*
* @param h
* Hash table to remove the key from.
@@ -318,9 +350,12 @@ rte_hash_get_key_with_position(const struct rte_hash *h, const int32_t position,
* of the key. This operation is not multi-thread safe and should
* only be called from one thread by default. Thread safety
* can be enabled by setting flag during table creation.
- * If RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL is enabled,
- * this API must be called, with the key index returned by rte_hash_add_key_xxx
- * APIs, after the key is deleted using rte_hash_del_key_xxx APIs.
+ * If RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL or
+ * RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled,
+ * the key index returned by rte_hash_del_key_xxx APIs must be freed
+ * using this API. This API should be called after all the readers
+ * have stopped referencing the entry corresponding to this key.
+ * RCU mechanisms could be used to determine such a state.
* This API does not validate if the key is already freed.
*
* @param h