> On Oct 20, 2020, at 9:42 PM, Wang, Yipeng1 <yipeng1.w...@intel.com> wrote:
>
>> -----Original Message-----
>> From: Dharmik Thakkar <dharmik.thak...@arm.com>
>> Sent: Tuesday, October 20, 2020 9:13 AM
>> To: Wang, Yipeng1 <yipeng1.w...@intel.com>; Gobriel, Sameh
>> <sameh.gobr...@intel.com>; Richardson, Bruce
>> <bruce.richard...@intel.com>; Ray Kinsella <m...@ashroe.eu>; Neil Horman
>> <nhor...@tuxdriver.com>
>> Cc: dev@dpdk.org; n...@arm.com; Dharmik Thakkar
>> <dharmik.thak...@arm.com>
>> Subject: [PATCH v5 2/4] lib/hash: integrate RCU QSBR
>>
>> Currently, users have to use external RCU mechanisms to free resources
>> when using lock free hash algorithm.
>>
>> Integrate RCU QSBR process to make it easier for the applications to use lock
>> free algorithm.
>> Refer to RCU documentation to understand various aspects of integrating RCU
>> library into other libraries.
>>
>> Suggested-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
>> Signed-off-by: Dharmik Thakkar <dharmik.thak...@arm.com>
>> Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com>
>> Acked-by: Ray Kinsella <m...@ashroe.eu>
>> ---
>> doc/guides/prog_guide/hash_lib.rst | 11 +-
>> lib/librte_hash/meson.build | 1 +
>> lib/librte_hash/rte_cuckoo_hash.c | 302 ++++++++++++++++++++++-------
>> lib/librte_hash/rte_cuckoo_hash.h | 8 +
>> lib/librte_hash/rte_hash.h | 77 +++++++-
>> lib/librte_hash/version.map | 2 +-
>> 6 files changed, 325 insertions(+), 76 deletions(-)
>>
>> diff --git a/doc/guides/prog_guide/hash_lib.rst
>> b/doc/guides/prog_guide/hash_lib.rst
>> index d06c7de2ead1..63e183ed1f08 100644
>> --- a/doc/guides/prog_guide/hash_lib.rst
>> +++ b/doc/guides/prog_guide/hash_lib.rst
>> @@ -102,6 +102,9 @@ For concurrent writes, and concurrent reads and
>> writes the following flag values
>> * If the 'do not free on delete' (RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL)
>> flag is set, the position of the entry in the hash table is not freed upon
>> calling
>> delete(). This flag is enabled
>> by default when the lock free read/write concurrency flag is set. The
>> application should free the position after all the readers have stopped
>> referencing the position.
>> Where required, the application can make use of RCU mechanisms to
>> determine when the readers have stopped referencing the position.
>> + RCU QSBR process is integrated within the Hash library for safe freeing
>> of
>> the position. Application has certain responsibilities while using this
>> feature.
>> + Please refer to resource reclamation framework of :ref:`RCU library
>> <RCU_Library>` for more details.
>
> [Yipeng]: Maybe also add: rte_hash_rcu_qsbr_add() need to be called to use
> the embedded RCU mechanism.
> Just to give user a pointer to which API to look.
Copy.
>> +
>>
>> Extendable Bucket Functionality support
>> ----------------------------------------
>> @@ -109,8 +112,8 @@ An extra flag is used to enable this functionality (flag
>> is not set by default).
>> in the very unlikely case due to excessive hash collisions that a key has
>> failed
>> to be inserted, the hash table bucket is extended with a linked list to
>> insert
>> these failed keys. This feature is important for the workloads (e.g. telco
>> workloads) that need to insert up to 100% of the hash table size and can't
>> tolerate any key insertion failure (even if very few).
>> -Please note that with the 'lock free read/write concurrency' flag enabled,
>> users need to call 'rte_hash_free_key_with_position' API in order to free the
>> empty buckets and -deleted keys, to maintain the 100% capacity guarantee.
>> +Please note that with the 'lock free read/write concurrency' flag
>> +enabled, users need to call 'rte_hash_free_key_with_position' API or
>> configure integrated RCU QSBR (or use external RCU mechanisms) in order to
>> free the empty buckets and deleted keys, to maintain the 100% capacity
>> guarantee.
>>
>> Implementation Details (non Extendable Bucket Case)
>> ---------------------------------------------------
>> @@ -172,7 +175,7 @@ Example of deletion:
>> Similar to lookup, the key is searched in its primary and secondary buckets.
>> If
>> the key is found, the entry is marked as empty. If the hash table was
>> configured with 'no free on delete' or 'lock free read/write concurrency',
>> the
>> position of the key is not freed. It is the responsibility of the user to
>> free the
>> position after -readers are not referencing the position anymore.
>> +readers are not referencing the position anymore. User can configure
>> +integrated RCU QSBR or use external RCU mechanisms to safely free the
>> +position on delete
>>
>>
>> Implementation Details (with Extendable Bucket) @@ -286,6 +289,8 @@ The
>> flow table operations on the application side are described below:
>> * Free flow: Free flow key position. If 'no free on delete' or 'lock-free
>> read/write concurrency' flags are set,
>> wait till the readers are not referencing the position returned during
>> add/delete flow and then free the position.
>> RCU mechanisms can be used to find out when the readers are not
>> referencing the position anymore.
>> + RCU QSBR process is integrated within the Hash library for safe freeing
>> of
>> the position. Application has certain responsibilities while using this
>> feature.
>> + Please refer to resource reclamation framework of :ref:`RCU library
>> <RCU_Library>` for more details.
>>
>> * Lookup flow: Lookup for the flow key in the hash.
>> If the returned position is valid (flow lookup hit), use the returned
>> position
>> to access the flow entry in the flow table.
>> diff --git a/lib/librte_hash/meson.build b/lib/librte_hash/meson.build index
>> 6ab46ae9d768..0977a63fd279 100644
>> --- a/lib/librte_hash/meson.build
>> +++ b/lib/librte_hash/meson.build
>> @@ -10,3 +10,4 @@ headers = files('rte_crc_arm64.h',
>>
>> sources = files('rte_cuckoo_hash.c', 'rte_fbk_hash.c') deps += ['ring']
>> +deps += ['rcu']
>> diff --git a/lib/librte_hash/rte_cuckoo_hash.c
>> b/lib/librte_hash/rte_cuckoo_hash.c
>> index aad0c965be5e..b9e4d82a0c14 100644
>> --- a/lib/librte_hash/rte_cuckoo_hash.c
>> +++ b/lib/librte_hash/rte_cuckoo_hash.c
>> @@ -52,6 +52,11 @@ static struct rte_tailq_elem rte_hash_tailq = { };
>> EAL_REGISTER_TAILQ(rte_hash_tailq)
>>
>> +struct __rte_hash_rcu_dq_entry {
>> + uint32_t key_idx;
>> + uint32_t ext_bkt_idx; /**< Extended bkt index */ };
>> +
>> struct rte_hash *
>> rte_hash_find_existing(const char *name) { @@ -210,7 +215,10 @@
>> rte_hash_create(const struct rte_hash_parameters *params)
>>
>> if (params->extra_flag &
>> RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF) {
>> readwrite_concur_lf_support = 1;
>> - /* Enable not freeing internal memory/index on delete */
>> + /* Enable not freeing internal memory/index on delete.
>> + * If internal RCU is enabled, freeing of internal memory/index
>> + * is done on delete
>> + */
>> no_free_on_del = 1;
>> }
>>
>> @@ -505,6 +513,10 @@ rte_hash_free(struct rte_hash *h)
>>
>> rte_mcfg_tailq_write_unlock();
>>
>> + /* RCU clean up. */
>> + if (h->dq)
>> + rte_rcu_qsbr_dq_delete(h->dq);
>> +
>> if (h->use_local_cache)
>> rte_free(h->local_free_slots);
>> if (h->writer_takes_lock)
>> @@ -607,11 +619,21 @@ void
>> rte_hash_reset(struct rte_hash *h)
>> {
>> uint32_t tot_ring_cnt, i;
>> + unsigned int pending;
>>
>> if (h == NULL)
>> return;
>>
>> __hash_rw_writer_lock(h);
>> +
>> + /* RCU QSBR clean up. */
>> + if (h->dq) {
>> + /* Reclaim all the resources */
>> + rte_rcu_qsbr_dq_reclaim(h->dq, ~0, NULL, &pending, NULL);
>> + if (pending != 0)
>> + RTE_LOG(ERR, HASH, "RCU reclaim all resources
>> failed\n");
>> + }
>> +
>> 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;
>> @@ -952,6 +974,37 @@ rte_hash_cuckoo_make_space_mw(const struct
>> rte_hash *h,
>> return -ENOSPC;
>> }
>>
>> +static inline uint32_t
>> +alloc_slot(const struct rte_hash *h, struct lcore_cache
>> +*cached_free_slots) {
>> + unsigned int n_slots;
>> + uint32_t slot_id;
>
> [Yipeng]: Blank line after variable declaration.
Copy.
>
>> + if (h->use_local_cache) {
>> + /* Try to get a free slot from the local cache */
>> + if (cached_free_slots->len == 0) {
>> + /* Need to get another burst of free slots from global
>> ring */
>> + n_slots = rte_ring_mc_dequeue_burst_elem(h-
>>> free_slots,
>> + cached_free_slots->objs,
>> + sizeof(uint32_t),
>> + LCORE_CACHE_SIZE, NULL);
>> + if (n_slots == 0)
>> + return EMPTY_SLOT;
>> +
>> + cached_free_slots->len += n_slots;
>> + }
>> +
>> + /* Get a free slot from the local cache */
>> + cached_free_slots->len--;
>> + slot_id = cached_free_slots->objs[cached_free_slots->len];
>> + } else {
>> + if (rte_ring_sc_dequeue_elem(h->free_slots, &slot_id,
>> + sizeof(uint32_t)) != 0)
>> + return EMPTY_SLOT;
>> + }
>> +
>> + return slot_id;
>> +}
>> +
>> static inline int32_t
>> __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
>> hash_sig_t sig, void *data)
>> @@ -963,7 +1016,6 @@ __rte_hash_add_key_with_hash(const struct
>> rte_hash *h, const void *key,
>> uint32_t ext_bkt_id = 0;
>> uint32_t slot_id;
>> int ret;
>> - unsigned n_slots;
>> unsigned lcore_id;
>> unsigned int i;
>> struct lcore_cache *cached_free_slots = NULL; @@ -1001,28
>> +1053,20 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h,
>> const void *key,
>> if (h->use_local_cache) {
>> lcore_id = rte_lcore_id();
>> cached_free_slots = &h->local_free_slots[lcore_id];
>> - /* Try to get a free slot from the local cache */
>> - if (cached_free_slots->len == 0) {
>> - /* Need to get another burst of free slots from global
>> ring */
>> - n_slots = rte_ring_mc_dequeue_burst_elem(h-
>>> free_slots,
>> - cached_free_slots->objs,
>> - sizeof(uint32_t),
>> - LCORE_CACHE_SIZE, NULL);
>> - if (n_slots == 0) {
>> - return -ENOSPC;
>> - }
>> -
>> - cached_free_slots->len += n_slots;
>> + }
>> + slot_id = alloc_slot(h, cached_free_slots);
>> + if (slot_id == EMPTY_SLOT) {
>> + if (h->dq) {
>> + __hash_rw_writer_lock(h);
>> + ret = rte_rcu_qsbr_dq_reclaim(h->dq,
>> + h->hash_rcu_cfg->max_reclaim_size,
>> + NULL, NULL, NULL);
>> + __hash_rw_writer_unlock(h);
>> + if (ret == 0)
>> + slot_id = alloc_slot(h, cached_free_slots);
>> }
>> -
>> - /* Get a free slot from the local cache */
>> - cached_free_slots->len--;
>> - slot_id = cached_free_slots->objs[cached_free_slots->len];
>> - } else {
>> - if (rte_ring_sc_dequeue_elem(h->free_slots, &slot_id,
>> - sizeof(uint32_t)) != 0) {
>> + if (slot_id == EMPTY_SLOT)
>> return -ENOSPC;
>> - }
>> }
>>
>> new_k = RTE_PTR_ADD(keys, slot_id * h->key_entry_size); @@ -
>> 1118,8 +1162,19 @@ __rte_hash_add_key_with_hash(const struct rte_hash
>> *h, const void *key,
>> if (rte_ring_sc_dequeue_elem(h->free_ext_bkts, &ext_bkt_id,
>> sizeof(uint32_t)) != 0 ||
>> ext_bkt_id == 0) {
>> - ret = -ENOSPC;
>> - goto failure;
>> + if (h->dq) {
>> + if (rte_rcu_qsbr_dq_reclaim(h->dq,
>> + h->hash_rcu_cfg->max_reclaim_size,
>> + NULL, NULL, NULL) == 0) {
>> + rte_ring_sc_dequeue_elem(h-
>>> free_ext_bkts,
>> + &ext_bkt_id,
>> + sizeof(uint32_t));
>> + }
>> + }
>> + if (ext_bkt_id == 0) {
>> + ret = -ENOSPC;
>> + goto failure;
>> + }
>> }
>>
>> /* Use the first location of the new bucket */ @@ -1395,12 +1450,12
>> @@ rte_hash_lookup_data(const struct rte_hash *h, const void *key, void
>> **data)
>> return __rte_hash_lookup_with_hash(h, key, rte_hash_hash(h, key),
>> data); }
>>
>> -static inline void
>> -remove_entry(const struct rte_hash *h, struct rte_hash_bucket *bkt,
>> unsigned i)
>> +static int
>> +free_slot(const struct rte_hash *h, uint32_t slot_id)
>> {
>> unsigned lcore_id, n_slots;
>> - struct lcore_cache *cached_free_slots;
>> -
>> + struct lcore_cache *cached_free_slots = NULL;
>> + /* Return key indexes to free slot ring */
>> if (h->use_local_cache) {
>> lcore_id = rte_lcore_id();
>> cached_free_slots = &h->local_free_slots[lcore_id]; @@ -
>> 1411,18 +1466,127 @@ remove_entry(const struct rte_hash *h, struct
>> rte_hash_bucket *bkt, unsigned i)
>> cached_free_slots->objs,
>> sizeof(uint32_t),
>> LCORE_CACHE_SIZE, NULL);
>> - ERR_IF_TRUE((n_slots == 0),
>> - "%s: could not enqueue free slots in global
>> ring\n",
>> - __func__);
>> + RETURN_IF_TRUE((n_slots == 0), -EFAULT);
>> cached_free_slots->len -= n_slots;
>> }
>> - /* Put index of new free slot in cache. */
>> - cached_free_slots->objs[cached_free_slots->len] =
>> - bkt->key_idx[i];
>> - cached_free_slots->len++;
>> + }
>> +
>> + enqueue_slot_back(h, cached_free_slots, slot_id);
>> + return 0;
>> +}
>> +
>> +static void
>> +__hash_rcu_qsbr_free_resource(void *p, void *e, unsigned int n) {
>> + void *key_data = NULL;
>> + int ret;
>> + struct rte_hash_key *keys, *k;
>> + struct rte_hash *h = (struct rte_hash *)p;
>> + struct __rte_hash_rcu_dq_entry rcu_dq_entry =
>> + *((struct __rte_hash_rcu_dq_entry *)e);
>> +
>> + RTE_SET_USED(n);
>> + keys = h->key_store;
>> +
>> + k = (struct rte_hash_key *) ((char *)keys +
>> + rcu_dq_entry.key_idx * h->key_entry_size);
>> + key_data = k->pdata;
>> + if (h->hash_rcu_cfg->free_key_data_func)
>> + h->hash_rcu_cfg->free_key_data_func(h->hash_rcu_cfg-
>>> key_data_ptr,
>> + key_data);
>> +
>> + if (h->ext_table_support && rcu_dq_entry.ext_bkt_idx !=
>> EMPTY_SLOT)
>> + /* Recycle empty ext bkt to free list. */
>> + rte_ring_sp_enqueue_elem(h->free_ext_bkts,
>> + &rcu_dq_entry.ext_bkt_idx, sizeof(uint32_t));
>> +
>> + /* Return key indexes to free slot ring */
>> + ret = free_slot(h, rcu_dq_entry.key_idx);
>> + if (ret < 0) {
>> + RTE_LOG(ERR, HASH,
>> + "%s: could not enqueue free slots in global ring\n",
>> + __func__);
>> + }
>> +}
>> +
>> +int
>> +rte_hash_rcu_qsbr_add(struct rte_hash *h,
>> + struct rte_hash_rcu_config *cfg)
>> +{
>> + struct rte_rcu_qsbr_dq_parameters params = {0};
>> + char rcu_dq_name[RTE_RCU_QSBR_DQ_NAMESIZE];
>> + struct rte_hash_rcu_config *hash_rcu_cfg = NULL;
>> +
>> + const uint32_t total_entries = h->use_local_cache ?
>> + h->entries + (RTE_MAX_LCORE - 1) * (LCORE_CACHE_SIZE - 1)
>> + 1
>> + : h->entries + 1;
>> +
>> + if ((h == NULL) || cfg == NULL || cfg->v == NULL) {
>> + rte_errno = EINVAL;
>> + return 1;
>> + }
>> +
>> + if (h->hash_rcu_cfg) {
>> + rte_errno = EEXIST;
>> + return 1;
>> + }
>> +
>> + hash_rcu_cfg = rte_zmalloc(NULL, sizeof(struct rte_hash_rcu_config),
>> 0);
>> + if (hash_rcu_cfg == NULL) {
>> + RTE_LOG(ERR, HASH, "memory allocation failed\n");
>> + return 1;
>> + }
>> +
>> + if (cfg->mode == RTE_HASH_QSBR_MODE_SYNC) {
>> + /* No other things to do. */
>> + } else if (cfg->mode == RTE_HASH_QSBR_MODE_DQ) {
>> + /* Init QSBR defer queue. */
>> + snprintf(rcu_dq_name, sizeof(rcu_dq_name),
>> + "HASH_RCU_%s", h->name);
>> + params.name = rcu_dq_name;
>> + params.size = cfg->dq_size;
>> + if (params.size == 0)
>> + params.size = total_entries;
>> + params.trigger_reclaim_limit = cfg->trigger_reclaim_limit;
>> + if (params.max_reclaim_size == 0)
>> + params.max_reclaim_size =
>> RTE_HASH_RCU_DQ_RECLAIM_MAX;
>> + params.esize = sizeof(struct __rte_hash_rcu_dq_entry);
>> + params.free_fn = __hash_rcu_qsbr_free_resource;
>> + params.p = h;
>> + params.v = cfg->v;
>> + h->dq = rte_rcu_qsbr_dq_create(¶ms);
>> + if (h->dq == NULL) {
>> + rte_free(hash_rcu_cfg);
>> + RTE_LOG(ERR, HASH, "HASH defer queue creation
>> failed\n");
>> + return 1;
>> + }
>> } else {
>> - rte_ring_sp_enqueue_elem(h->free_slots,
>> - &bkt->key_idx[i], sizeof(uint32_t));
>> + rte_free(hash_rcu_cfg);
>> + rte_errno = EINVAL;
>> + return 1;
>> + }
>> +
>> + hash_rcu_cfg->v = cfg->v;
>> + hash_rcu_cfg->mode = cfg->mode;
>> + hash_rcu_cfg->dq_size = params.size;
>> + hash_rcu_cfg->trigger_reclaim_limit = params.trigger_reclaim_limit;
>> + hash_rcu_cfg->max_reclaim_size = params.max_reclaim_size;
>> + hash_rcu_cfg->free_key_data_func = cfg->free_key_data_func;
>> + hash_rcu_cfg->key_data_ptr = cfg->key_data_ptr;
>> +
>> + h->hash_rcu_cfg = hash_rcu_cfg;
>> +
>> + return 0;
>> +}
>> +
>> +static inline void
>> +remove_entry(const struct rte_hash *h, struct rte_hash_bucket *bkt,
>> +unsigned i) {
>> + int ret = free_slot(h, bkt->key_idx[i]);
>> + if (ret < 0) {
>> + RTE_LOG(ERR, HASH,
>> + "%s: could not enqueue free slots in global ring\n",
>> + __func__);
>> }
>> }
>>
>> @@ -1521,6 +1685,8 @@ __rte_hash_del_key_with_hash(const struct
>> rte_hash *h, const void *key,
>> int pos;
>> int32_t ret, i;
>> uint16_t short_sig;
>> + uint32_t index = EMPTY_SLOT;
>> + struct __rte_hash_rcu_dq_entry rcu_dq_entry;
>>
>> short_sig = get_short_sig(sig);
>> prim_bucket_idx = get_prim_bucket_index(h, sig); @@ -1555,10
>> +1721,9 @@ __rte_hash_del_key_with_hash(const struct rte_hash *h, const
>> void *key,
>>
>> /* Search last bucket to see if empty to be recycled */
>> return_bkt:
>> - if (!last_bkt) {
>> - __hash_rw_writer_unlock(h);
>> - return ret;
>> - }
>> + if (!last_bkt)
>> + goto return_key;
>> +
>> while (last_bkt->next) {
>> prev_bkt = last_bkt;
>> last_bkt = last_bkt->next;
>> @@ -1571,11 +1736,11 @@ __rte_hash_del_key_with_hash(const struct
>> rte_hash *h, const void *key,
>> /* found empty bucket and recycle */
>> if (i == RTE_HASH_BUCKET_ENTRIES) {
>> prev_bkt->next = NULL;
>> - uint32_t index = last_bkt - h->buckets_ext + 1;
>> + index = last_bkt - h->buckets_ext + 1;
>> /* Recycle the empty bkt if
>> * no_free_on_del is disabled.
>> */
>> - if (h->no_free_on_del)
>> + if (h->no_free_on_del) {
>> /* Store index of an empty ext bkt to be recycled
>> * on calling rte_hash_del_xxx APIs.
>> * When lock free read-write concurrency is enabled,
>> @@ -1583,12 +1748,34 @@ __rte_hash_del_key_with_hash(const struct
>> rte_hash *h, const void *key,
>> * immediately (as readers might be using it still).
>> * Hence freeing of the ext bkt is piggy-backed to
>> * freeing of the key index.
>> + * If using external RCU, store this index in an array.
>> */
>> - h->ext_bkt_to_free[ret] = index;
>> - else
>> + if (h->hash_rcu_cfg == NULL)
>> + h->ext_bkt_to_free[ret] = index;
>
>
> [Yipeng]: If using embedded qsbr (not NULL), how did you recycle the ext bkt?
In DQ mode, ext_bkt_idx is enqueued to the defer queue along with the key_idx
and recycled as
part of rte_rcu_qsbr_dq_reclaim(). In SYNC mode, it is recycled after
rte_rcu_qsbr_synchronize() succeeds.
>
>> + } else
>> rte_ring_sp_enqueue_elem(h->free_ext_bkts,
>> &index,
>> sizeof(uint32_t));
>> }
>> +
>> +return_key:
>> + /* Using internal RCU QSBR */
>> + if (h->hash_rcu_cfg) {
>> + /* Key index where key is stored, adding the first dummy
>> index */
>> + rcu_dq_entry.key_idx = ret + 1;
>> + rcu_dq_entry.ext_bkt_idx = index;
>> + if (h->dq == NULL) {
>> + /* Wait for quiescent state change if using
>> + * RTE_HASH_QSBR_MODE_SYNC
>> + */
>> + rte_rcu_qsbr_synchronize(h->hash_rcu_cfg->v,
>> + RTE_QSBR_THRID_INVALID);
>> + __hash_rcu_qsbr_free_resource((void
>> *)((uintptr_t)h),
>> + &rcu_dq_entry, 1);
>> + } else if (h->dq)
>> + /* Push into QSBR FIFO if using
>> RTE_HASH_QSBR_MODE_DQ */
>> + if (rte_rcu_qsbr_dq_enqueue(h->dq,
>> &rcu_dq_entry) != 0)
>> + RTE_LOG(ERR, HASH, "Failed to push QSBR
>> FIFO\n");
>> + }
>> __hash_rw_writer_unlock(h);
>> return ret;
>> }
>> @@ -1637,8 +1824,6 @@ rte_hash_free_key_with_position(const struct
>> rte_hash *h,
>>
>> RETURN_IF_TRUE(((h == NULL) || (key_idx == EMPTY_SLOT)), -EINVAL);
>>
>> - unsigned int lcore_id, n_slots;
>> - struct lcore_cache *cached_free_slots;
>> const uint32_t total_entries = h->use_local_cache ?
>> h->entries + (RTE_MAX_LCORE - 1) * (LCORE_CACHE_SIZE - 1)
>> + 1
>> : h->entries + 1;
>> @@ -1656,28 +1841,9 @@ rte_hash_free_key_with_position(const struct
>> rte_hash *h,
>> }
>> }
>>
>> - if (h->use_local_cache) {
>> - lcore_id = rte_lcore_id();
>> - cached_free_slots = &h->local_free_slots[lcore_id];
>> - /* Cache full, need to free it. */
>> - if (cached_free_slots->len == LCORE_CACHE_SIZE) {
>> - /* Need to enqueue the free slots in global ring. */
>> - n_slots = rte_ring_mp_enqueue_burst_elem(h-
>>> free_slots,
>> - cached_free_slots->objs,
>> - sizeof(uint32_t),
>> - LCORE_CACHE_SIZE, NULL);
>> - RETURN_IF_TRUE((n_slots == 0), -EFAULT);
>> - cached_free_slots->len -= n_slots;
>> - }
>> - /* Put index of new free slot in cache. */
>> - cached_free_slots->objs[cached_free_slots->len] = key_idx;
>> - cached_free_slots->len++;
>> - } else {
>> - rte_ring_sp_enqueue_elem(h->free_slots, &key_idx,
>> - sizeof(uint32_t));
>> - }
>> + /* Enqueue slot to cache/ring of free slots. */
>> + return free_slot(h, key_idx);
>>
>> - return 0;
>> }
>>
>> static inline void
>> diff --git a/lib/librte_hash/rte_cuckoo_hash.h
>> b/lib/librte_hash/rte_cuckoo_hash.h
>> index 345de6bf9cfd..85be49d3bbe7 100644
>> --- a/lib/librte_hash/rte_cuckoo_hash.h
>> +++ b/lib/librte_hash/rte_cuckoo_hash.h
>> @@ -168,6 +168,11 @@ struct rte_hash {
>> struct lcore_cache *local_free_slots;
>> /**< Local cache per lcore, storing some indexes of the free slots */
>>
>> + /* RCU config */
>> + struct rte_hash_rcu_config *hash_rcu_cfg;
>> + /**< HASH RCU QSBR configuration structure */
>> + struct rte_rcu_qsbr_dq *dq; /**< RCU QSBR defer queue. */
>> +
>> /* Fields used in lookup */
>>
>> uint32_t key_len __rte_cache_aligned;
>> @@ -230,4 +235,7 @@ struct queue_node {
>> int prev_slot; /* Parent(slot) in search path */
>> };
>>
>> +/** @internal Default RCU defer queue entries to reclaim in one go. */
>> +#define RTE_HASH_RCU_DQ_RECLAIM_MAX 16
>> +
>> #endif
>> diff --git a/lib/librte_hash/rte_hash.h b/lib/librte_hash/rte_hash.h index
>> bff40251bc98..3d28f177f14a 100644
>> --- a/lib/librte_hash/rte_hash.h
>> +++ b/lib/librte_hash/rte_hash.h
>> @@ -15,6 +15,7 @@
>> #include <stddef.h>
>>
>> #include <rte_compat.h>
>> +#include <rte_rcu_qsbr.h>
>>
>> #ifdef __cplusplus
>> extern "C" {
>> @@ -45,7 +46,8 @@ 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.
>> + * is enabled. However, if internal RCU is enabled, freeing of internal
>> + * memory/index is done on delete
>> */
>> #define RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL 0x10
>>
>> @@ -67,6 +69,13 @@ typedef uint32_t (*rte_hash_function)(const void
>> *key, uint32_t key_len,
>> /** Type of function used to compare the hash key. */ typedef int
>> (*rte_hash_cmp_eq_t)(const void *key1, const void *key2, size_t key_len);
>>
>> +/**
>> + * Type of function used to free data stored in the key.
>> + * Required when using internal RCU to allow application to free
>> +key-data once
>> + * the key is returned to the the ring of free key-slots.
>> + */
>> +typedef void (*rte_hash_free_key_data)(void *p, void *key_data);
>> +
>> /**
>> * Parameters used when creating the hash table.
>> */
>> @@ -81,6 +90,39 @@ struct rte_hash_parameters {
>> uint8_t extra_flag; /**< Indicate if additional parameters
>> are present. */
>> };
>>
>> +/** RCU reclamation modes */
>> +enum rte_hash_qsbr_mode {
>> + /** Create defer queue for reclaim. */
>> + RTE_HASH_QSBR_MODE_DQ = 0,
>> + /** Use blocking mode reclaim. No defer queue created. */
>> + RTE_HASH_QSBR_MODE_SYNC
>> +};
>> +
>> +/** HASH RCU QSBR configuration structure. */ struct
>> +rte_hash_rcu_config {
>> + struct rte_rcu_qsbr *v; /**< RCU QSBR variable. */
>> + enum rte_hash_qsbr_mode mode;
>> + /**< Mode of RCU QSBR. RTE_HASH_QSBR_MODE_xxx
>> + * '0' for default: create defer queue for reclaim.
>> + */
>> + uint32_t dq_size;
>> + /**< RCU defer queue size.
>> + * default: total hash table entries.
>> + */
>> + uint32_t trigger_reclaim_limit; /**< Threshold to trigger auto reclaim.
>> */
>> + uint32_t max_reclaim_size;
>> + /**< Max entries to reclaim in one go.
>> + * default: RTE_HASH_RCU_DQ_RECLAIM_MAX.
>> + */
>> + void *key_data_ptr;
>> + /**< Pointer passed to the free function. Typically, this is the
>> + * pointer to the data structure to which the resource to free
>> + * (key-data) belongs. This can be NULL.
>> + */
>> + rte_hash_free_key_data free_key_data_func;
>> + /**< Function to call to free the resource (key-data). */ };
>> +
>> /** @internal A hash table structure. */ struct rte_hash;
>>
>> @@ -287,7 +329,8 @@ rte_hash_add_key_with_hash(const struct rte_hash
>> *h, const void *key, hash_sig_t
>> * Thread safety can be enabled by setting flag during
>> * table creation.
>> * If RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL or
>> - * RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled,
>> + * RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled and
>> + * internal RCU is NOT 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.
>> @@ -316,7 +359,8 @@ rte_hash_del_key(const struct rte_hash *h, const
>> void *key);
>> * Thread safety can be enabled by setting flag during
>> * table creation.
>> * If RTE_HASH_EXTRA_FLAGS_NO_FREE_ON_DEL or
>> - * RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled,
>> + * RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled and
>> + * internal RCU is NOT 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.
>> @@ -370,7 +414,8 @@ rte_hash_get_key_with_position(const struct
>> rte_hash *h, const int32_t position,
>> * 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 or
>> - * RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled,
>> + * RTE_HASH_EXTRA_FLAGS_RW_CONCURRENCY_LF is enabled and
>> + * internal RCU is NOT 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.
>> @@ -625,6 +670,30 @@ rte_hash_lookup_bulk(const struct rte_hash *h,
>> const void **keys,
>> */
>> int32_t
>> rte_hash_iterate(const struct rte_hash *h, const void **key, void **data,
>> uint32_t *next);
>> +
>> +/**
>> + * @warning
>> + * @b EXPERIMENTAL: this API may change without prior notice
>> + *
>> + * Associate RCU QSBR variable with an Hash object.
> [Yipeng]: a Hash object
Copy.
>
>> + * This API should be called to enable the integrated RCU QSBR support
>> +and
>> + * should be called immediately after creating the Hash object.
>> + *
>> + * @param h
>> + * the hash object to add RCU QSBR
>> + * @param cfg
>> + * RCU QSBR configuration
>> + * @return
>> + * On success - 0
>> + * On error - 1 with error code set in rte_errno.
>> + * Possible rte_errno codes are:
>> + * - EINVAL - invalid pointer
>> + * - EEXIST - already added QSBR
>> + * - ENOMEM - memory allocation failure
>> + */
>> +__rte_experimental
>> +int rte_hash_rcu_qsbr_add(struct rte_hash *h,
>> + struct rte_hash_rcu_config *cfg);
>> #ifdef __cplusplus
>> }
>> #endif
>> diff --git a/lib/librte_hash/version.map b/lib/librte_hash/version.map index
>> c0db81014ff9..c6d73080f478 100644
>> --- a/lib/librte_hash/version.map
>> +++ b/lib/librte_hash/version.map
>> @@ -36,5 +36,5 @@ EXPERIMENTAL {
>> rte_hash_lookup_with_hash_bulk;
>> rte_hash_lookup_with_hash_bulk_data;
>> rte_hash_max_key_id;
>> -
>> + rte_hash_rcu_qsbr_add;
>> };
>> --
>> 2.17.1
> [Yipeng]:
>
> Hi, Dharmik, thanks for the work! It generally looks good.
> Just some minor issues to address and one question for the ext table inlined.
Thank you for the comments, Yipeng! I will update the patches.
>
> Thanks!
