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From: "Wang, Yipeng1" <yipeng1.wang@intel.com>
To: Dharmik Thakkar <dharmik.thakkar@arm.com>,
	"Gobriel, Sameh" <sameh.gobriel@intel.com>,
	"Richardson, Bruce" <bruce.richardson@intel.com>,
	Ray Kinsella <mdr@ashroe.eu>, Neil Horman <nhorman@tuxdriver.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>, "nd@arm.com" <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH v5 2/4] lib/hash: integrate RCU QSBR
Date: Wed, 21 Oct 2020 02:42:33 +0000
Message-ID: <BYAPR11MB34948CA2C858032FF6BFBB1EC31C0@BYAPR11MB3494.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20201020161301.7458-3-dharmik.thakkar@arm.com>

> -----Original Message-----
> From: Dharmik Thakkar <dharmik.thakkar@arm.com>
> Sent: Tuesday, October 20, 2020 9:13 AM
> To: Wang, Yipeng1 <yipeng1.wang@intel.com>; Gobriel, Sameh
> <sameh.gobriel@intel.com>; Richardson, Bruce
> <bruce.richardson@intel.com>; Ray Kinsella <mdr@ashroe.eu>; Neil Horman
> <nhorman@tuxdriver.com>
> Cc: dev@dpdk.org; nd@arm.com; Dharmik Thakkar
> <dharmik.thakkar@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.nagarahalli@arm.com>
> Signed-off-by: Dharmik Thakkar <dharmik.thakkar@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> Acked-by: Ray Kinsella <mdr@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.
> +
> 
>  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.

> +	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(&params);
> +		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?

> +		} 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

> + * 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.

Thanks!





  reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-01  6:58 [dpdk-dev] [RFC 0/3] RCU integration with hash library Dharmik Thakkar
2019-09-01  6:58 ` [dpdk-dev] [RFC 1/3] net/ixgbe: avoid multpile definitions of 'bool' Dharmik Thakkar
2019-09-05 15:26   ` Stephen Hemminger
2019-09-05 20:10     ` Dharmik Thakkar
2019-09-05 20:23       ` Stephen Hemminger
2019-09-01  6:58 ` [dpdk-dev] [RFC 2/3] lib/hash: integrate RCU QSBR Dharmik Thakkar
2019-09-01  6:58 ` [dpdk-dev] [RFC 3/3] test/hash: add tests for integrated " Dharmik Thakkar
2019-09-05 21:31 ` [dpdk-dev] [RFC 0/3] RCU integration with hash library Wang, Yipeng1
2020-08-19  4:05 ` [dpdk-dev] [RFC v2] lib/hash: integrate RCU QSBR Dharmik Thakkar
2020-08-25 19:59   ` Dharmik Thakkar
2020-08-31 20:47   ` Wang, Yipeng1
2020-09-01 22:01     ` Dharmik Thakkar
2020-10-16 13:53       ` David Marchand
2020-10-16 15:04         ` Dharmik Thakkar
2020-10-16 17:38   ` [dpdk-dev] [PATCH 0/3] hash: " Dharmik Thakkar
2020-10-16 17:38     ` [dpdk-dev] [PATCH v3 1/3] lib/hash: " Dharmik Thakkar
2020-10-19  9:43       ` Kinsella, Ray
2020-10-16 17:38     ` [dpdk-dev] [PATCH v3 2/3] test/hash: replace rte atomic with C11 atomic APIs Dharmik Thakkar
2020-10-16 17:38     ` [dpdk-dev] [PATCH v3 3/3] test/hash: add tests for integrated RCU QSBR Dharmik Thakkar
2020-10-19 14:48     ` [dpdk-dev] [PATCH 0/3] hash: integrate " David Marchand
2020-10-19 16:35     ` [dpdk-dev] [PATCH v4 " Dharmik Thakkar
2020-10-19 16:35       ` [dpdk-dev] [PATCH v4 1/3] lib/hash: " Dharmik Thakkar
2020-10-19 16:35       ` [dpdk-dev] [PATCH v4 2/3] test/hash: replace rte atomic with C11 atomic APIs Dharmik Thakkar
2020-10-19 16:35       ` [dpdk-dev] [PATCH v4 3/3] test/hash: add tests for integrated RCU QSBR Dharmik Thakkar
2020-10-19 21:05       ` [dpdk-dev] [PATCH v4 0/3] hash: integrate " David Marchand
2020-10-20  4:08         ` Dharmik Thakkar
2020-10-20 16:12       ` [dpdk-dev] [PATCH v5 0/4] " Dharmik Thakkar
2020-10-20 16:12         ` [dpdk-dev] [PATCH v5 1/4] rcu: build on Windows Dharmik Thakkar
2020-10-20 16:12         ` [dpdk-dev] [PATCH v5 2/4] lib/hash: integrate RCU QSBR Dharmik Thakkar
2020-10-21  2:42           ` Wang, Yipeng1 [this message]
2020-10-21  4:52             ` Dharmik Thakkar
2020-10-20 16:13         ` [dpdk-dev] [PATCH v5 3/4] test/hash: replace rte atomic with C11 atomic APIs Dharmik Thakkar
2020-10-21  2:52           ` Wang, Yipeng1
2020-10-20 16:13         ` [dpdk-dev] [PATCH v5 4/4] test/hash: add tests for integrated RCU QSBR Dharmik Thakkar
2020-10-21  3:54           ` Wang, Yipeng1
2020-10-21  4:55             ` Dharmik Thakkar
2020-10-21 22:34             ` Honnappa Nagarahalli
2020-10-21 22:50         ` [dpdk-dev] [PATCH v6 0/4] hash: integrate " Dharmik Thakkar
2020-10-21 22:50           ` [dpdk-dev] [PATCH v6 1/4] rcu: build on Windows Dharmik Thakkar
2020-10-22  9:05             ` David Marchand
2020-10-22 18:35             ` Kadam, Pallavi
2020-10-21 22:50           ` [dpdk-dev] [PATCH v6 2/4] lib/hash: integrate RCU QSBR Dharmik Thakkar
2020-10-23 21:46             ` Dharmik Thakkar
2020-10-23 22:08             ` Wang, Yipeng1
2020-10-21 22:50           ` [dpdk-dev] [PATCH v6 3/4] test/hash: replace rte atomic with C11 atomic APIs Dharmik Thakkar
2020-10-21 22:50           ` [dpdk-dev] [PATCH v6 4/4] test/hash: add tests for integrated RCU QSBR Dharmik Thakkar
2020-10-23 22:11             ` Wang, Yipeng1
2020-10-24  9:09           ` [dpdk-dev] [PATCH v6 0/4] hash: integrate " David Marchand
2020-10-26 13:56             ` Dharmik Thakkar

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