[dpdk-dev] [PATCH v6 2/2] librte_lpm: Improve performance of the delete and add functions

[dpdk-dev] [PATCH v6 2/2] librte_lpm: Improve performance of the delete and add functions

[Alex Kiselev]

librte_lpm: Improve lpm6 performance

There is no need to rebuild the whole LPM tree
when a rule is deleted. This patch addresses this
issue introducing new delete operation.

Signed-off-by: Alex Kiselev <alex@therouter.net>
---
 lib/librte_lpm/rte_lpm6.c | 712 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 597 insertions(+), 115 deletions(-)

diff --git a/lib/librte_lpm/rte_lpm6.c b/lib/librte_lpm/rte_lpm6.c
index d86e878bc..6f1f94e23 100644
--- a/lib/librte_lpm/rte_lpm6.c
+++ b/lib/librte_lpm/rte_lpm6.c
@@ -41,6 +41,7 @@
 #define BYTES2_SIZE                              16
 
 #define RULE_HASH_TABLE_EXTRA_SPACE              64
+#define TBL24_IND                        UINT32_MAX
 
 #define lpm6_tbl8_gindex next_hop
 
@@ -81,6 +82,17 @@ struct rte_lpm6_rule_key {
 	uint8_t depth; /**< Rule depth. */
 };
 
+/* Header of tbl8 */
+struct rte_lpm_tbl8_hdr {
+	uint32_t owner_tbl_ind; /**< owner table: TBL24_IND if owner is tbl24,
+					* otherwise index of tbl8
+					*/
+	uint32_t owner_entry_ind; /**< index of the owner table entry where
+					* pointer to the tbl8 is stored
+					*/
+	uint32_t ref_cnt; /**< table reference counter */
+};
+
 /** LPM6 structure. */
 struct rte_lpm6 {
 	/* LPM metadata. */
@@ -88,12 +100,17 @@ struct rte_lpm6 {
 	uint32_t max_rules;              /**< Max number of rules. */
 	uint32_t used_rules;             /**< Used rules so far. */
 	uint32_t number_tbl8s;           /**< Number of tbl8s to allocate. */
-	uint32_t next_tbl8;              /**< Next tbl8 to be used. */
 
 	/* LPM Tables. */
 	struct rte_hash *rules_tbl; /**< LPM rules. */
 	struct rte_lpm6_tbl_entry tbl24[RTE_LPM6_TBL24_NUM_ENTRIES]
 			__rte_cache_aligned; /**< LPM tbl24 table. */
+
+	uint32_t *tbl8_pool; /**< pool of indexes of free tbl8s */
+	uint32_t tbl8_pool_pos; /**< current position in the tbl8 pool */
+
+	struct rte_lpm_tbl8_hdr *tbl8_hdrs; /* array of tbl8 headers */
+
 	struct rte_lpm6_tbl_entry tbl8[0]
 			__rte_cache_aligned; /**< LPM tbl8 table. */
 };
@@ -142,6 +159,59 @@ rule_hash(const void *data, __rte_unused uint32_t data_len,
 	return rte_jhash(data, sizeof(struct rte_lpm6_rule_key), init_val);
 }
 
+/*
+ * Init pool of free tbl8 indexes
+ */
+static void
+tbl8_pool_init(struct rte_lpm6 *lpm)
+{
+	uint32_t i;
+
+	/* put entire range of indexes to the tbl8 pool */
+	for (i = 0; i < lpm->number_tbl8s; i++)
+		lpm->tbl8_pool[i] = i;
+
+	lpm->tbl8_pool_pos = 0;
+}
+
+/*
+ * Get an index of a free tbl8 from the pool
+ */
+static inline uint32_t
+tbl8_get(struct rte_lpm6 *lpm, uint32_t *tbl8_ind)
+{
+	if (lpm->tbl8_pool_pos == lpm->number_tbl8s)
+		/* no more free tbl8 */
+		return -ENOSPC;
+
+	/* next index */
+	*tbl8_ind = lpm->tbl8_pool[lpm->tbl8_pool_pos++];
+	return 0;
+}
+
+/*
+ * Put an index of a free tbl8 back to the pool
+ */
+static inline uint32_t
+tbl8_put(struct rte_lpm6 *lpm, uint32_t tbl8_ind)
+{
+	if (lpm->tbl8_pool_pos == 0)
+		/* pool is full */
+		return -ENOSPC;
+
+	lpm->tbl8_pool[--lpm->tbl8_pool_pos] = tbl8_ind;
+	return 0;
+}
+
+/*
+ * Returns number of tbl8s available in the pool
+ */
+static inline uint32_t
+tbl8_available(struct rte_lpm6 *lpm)
+{
+	return lpm->number_tbl8s - lpm->tbl8_pool_pos;
+}
+
 /*
  * Init a rule key.
  *	  note that ip must be already masked
@@ -182,6 +252,8 @@ rte_lpm6_create(const char *name, int socket_id,
 	uint64_t mem_size;
 	struct rte_lpm6_list *lpm_list;
 	struct rte_hash *rules_tbl = NULL;
+	uint32_t *tbl8_pool = NULL;
+	struct rte_lpm_tbl8_hdr *tbl8_hdrs = NULL;
 
 	lpm_list = RTE_TAILQ_CAST(rte_lpm6_tailq.head, rte_lpm6_list);
 
@@ -216,6 +288,28 @@ rte_lpm6_create(const char *name, int socket_id,
 		goto fail_wo_unlock;
 	}
 
+	/* allocate tbl8 indexes pool */
+	tbl8_pool = rte_malloc(NULL,
+			sizeof(uint32_t) * config->number_tbl8s,
+			RTE_CACHE_LINE_SIZE);
+	if (tbl8_pool == NULL) {
+		RTE_LOG(ERR, LPM, "LPM tbl8 pool allocation failed: %s (%d)",
+				  rte_strerror(rte_errno), rte_errno);
+		rte_errno = ENOMEM;
+		goto fail_wo_unlock;
+	}
+
+	/* allocate tbl8 headers */
+	tbl8_hdrs = rte_malloc(NULL,
+			sizeof(struct rte_lpm_tbl8_hdr) * config->number_tbl8s,
+			RTE_CACHE_LINE_SIZE);
+	if (tbl8_hdrs == NULL) {
+		RTE_LOG(ERR, LPM, "LPM tbl8 headers allocation failed: %s (%d)",
+				  rte_strerror(rte_errno), rte_errno);
+		rte_errno = ENOMEM;
+		goto fail_wo_unlock;
+	}
+
 	snprintf(mem_name, sizeof(mem_name), "LPM_%s", name);
 
 	/* Determine the amount of memory to allocate. */
@@ -260,6 +354,11 @@ rte_lpm6_create(const char *name, int socket_id,
 	lpm->number_tbl8s = config->number_tbl8s;
 	snprintf(lpm->name, sizeof(lpm->name), "%s", name);
 	lpm->rules_tbl = rules_tbl;
+	lpm->tbl8_pool = tbl8_pool;
+	lpm->tbl8_hdrs = tbl8_hdrs;
+
+	/* init the stack */
+	tbl8_pool_init(lpm);
 
 	te->data = (void *) lpm;
 
@@ -271,6 +370,8 @@ rte_lpm6_create(const char *name, int socket_id,
 	rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
 
 fail_wo_unlock:
+	rte_free(tbl8_hdrs);
+	rte_free(tbl8_pool);
 	rte_hash_free(rules_tbl);
 
 	return NULL;
@@ -332,6 +433,8 @@ rte_lpm6_free(struct rte_lpm6 *lpm)
 
 	rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
 
+	rte_free(lpm->tbl8_hdrs);
+	rte_free(lpm->tbl8_pool);
 	rte_hash_free(lpm->rules_tbl);
 	rte_free(lpm);
 	rte_free(te);
@@ -420,24 +523,24 @@ rule_add(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth, uint32_t next_hop)
  * in the IP address returns a match.
  */
 static void
-expand_rule(struct rte_lpm6 *lpm, uint32_t tbl8_gindex, uint8_t depth,
-		uint32_t next_hop)
+expand_rule(struct rte_lpm6 *lpm, uint32_t tbl8_gindex, uint8_t old_depth,
+		uint8_t new_depth, uint32_t next_hop, uint8_t valid)
 {
 	uint32_t tbl8_group_end, tbl8_gindex_next, j;
 
 	tbl8_group_end = tbl8_gindex + RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
 
 	struct rte_lpm6_tbl_entry new_tbl8_entry = {
-		.valid = VALID,
-		.valid_group = VALID,
-		.depth = depth,
+		.valid = valid,
+		.valid_group = valid,
+		.depth = new_depth,
 		.next_hop = next_hop,
 		.ext_entry = 0,
 	};
 
 	for (j = tbl8_gindex; j < tbl8_group_end; j++) {
 		if (!lpm->tbl8[j].valid || (lpm->tbl8[j].ext_entry == 0
-				&& lpm->tbl8[j].depth <= depth)) {
+				&& lpm->tbl8[j].depth <= old_depth)) {
 
 			lpm->tbl8[j] = new_tbl8_entry;
 
@@ -445,11 +548,101 @@ expand_rule(struct rte_lpm6 *lpm, uint32_t tbl8_gindex, uint8_t depth,
 
 			tbl8_gindex_next = lpm->tbl8[j].lpm6_tbl8_gindex
 					* RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
-			expand_rule(lpm, tbl8_gindex_next, depth, next_hop);
+			expand_rule(lpm, tbl8_gindex_next, old_depth, new_depth,
+					next_hop, valid);
 		}
 	}
 }
 
+/*
+ * Init a tbl8 header
+ */
+static inline void
+init_tbl8_header(struct rte_lpm6 *lpm, uint32_t tbl_ind,
+		uint32_t owner_tbl_ind, uint32_t owner_entry_ind)
+{
+	struct rte_lpm_tbl8_hdr *tbl_hdr = &lpm->tbl8_hdrs[tbl_ind];
+	tbl_hdr->owner_tbl_ind = owner_tbl_ind;
+	tbl_hdr->owner_entry_ind = owner_entry_ind;
+	tbl_hdr->ref_cnt = 0;
+}
+
+/*
+ * Calculate index to the table based on the number and position
+ * of the bytes being inspected in this step.
+ */
+static uint32_t
+get_bitshift(const uint8_t *ip, uint8_t first_byte, uint8_t bytes)
+{
+	uint32_t entry_ind, i;
+	int8_t bitshift;
+
+	entry_ind = 0;
+	for (i = first_byte; i < (uint32_t)(first_byte + bytes); i++) {
+		bitshift = (int8_t)((bytes - i)*BYTE_SIZE);
+
+		if (bitshift < 0)
+			bitshift = 0;
+		entry_ind = entry_ind | ip[i-1] << bitshift;
+	}
+
+	return entry_ind;
+}
+
+/*
+ * Simulate adding a new route to the LPM counting number
+ * of new tables that will be needed
+ *
+ * It returns 0 on success, or 1 if
+ * the process needs to be continued by calling the function again.
+ */
+static inline int
+simulate_add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
+		struct rte_lpm6_tbl_entry **next_tbl, const uint8_t *ip,
+		uint8_t bytes, uint8_t first_byte, uint8_t depth,
+		uint32_t *need_tbl_nb)
+{
+	uint32_t entry_ind;
+	uint8_t bits_covered;
+	uint32_t next_tbl_ind;
+
+	/*
+	 * Calculate index to the table based on the number and position
+	 * of the bytes being inspected in this step.
+	 */
+	entry_ind = get_bitshift(ip, first_byte, bytes);
+
+	/* Number of bits covered in this step */
+	bits_covered = (uint8_t)((bytes+first_byte-1)*BYTE_SIZE);
+
+	if (depth <= bits_covered) {
+		*need_tbl_nb = 0;
+		return 0;
+	}
+
+	if (tbl[entry_ind].valid == 0 || tbl[entry_ind].ext_entry == 0) {
+		/* from this point on a new table is needed on each level
+		 * that is not covered yet
+		 */
+		depth -= bits_covered;
+		uint32_t cnt = depth >> 3; /* depth / BYTE_SIZE */
+		if (depth & 7) /* 0b00000111 */
+			/* if depth % 8 > 0 then one more table is needed
+			 * for those last bits
+			 */
+			cnt++;
+
+		*need_tbl_nb = cnt;
+		return 0;
+	}
+
+	next_tbl_ind = tbl[entry_ind].lpm6_tbl8_gindex;
+	*next_tbl = &(lpm->tbl8[next_tbl_ind *
+		RTE_LPM6_TBL8_GROUP_NUM_ENTRIES]);
+	*need_tbl_nb = 0;
+	return 1;
+}
+
 /*
  * Partially adds a new route to the data structure (tbl24+tbl8s).
  * It returns 0 on success, a negative number on failure, or 1 if
@@ -457,25 +650,21 @@ expand_rule(struct rte_lpm6 *lpm, uint32_t tbl8_gindex, uint8_t depth,
  */
 static inline int
 add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
-		struct rte_lpm6_tbl_entry **tbl_next, uint8_t *ip, uint8_t bytes,
-		uint8_t first_byte, uint8_t depth, uint32_t next_hop)
+		uint32_t tbl_ind, struct rte_lpm6_tbl_entry **next_tbl,
+		uint32_t *next_tbl_ind, uint8_t *ip, uint8_t bytes,
+		uint8_t first_byte, uint8_t depth, uint32_t next_hop,
+		uint8_t is_new_rule)
 {
-	uint32_t tbl_index, tbl_range, tbl8_group_start, tbl8_group_end, i;
-	int32_t tbl8_gindex;
-	int8_t bitshift;
+	uint32_t entry_ind, tbl_range, tbl8_group_start, tbl8_group_end, i;
+	uint32_t tbl8_gindex;
 	uint8_t bits_covered;
+	int ret;
 
 	/*
 	 * Calculate index to the table based on the number and position
 	 * of the bytes being inspected in this step.
 	 */
-	tbl_index = 0;
-	for (i = first_byte; i < (uint32_t)(first_byte + bytes); i++) {
-		bitshift = (int8_t)((bytes - i)*BYTE_SIZE);
-
-		if (bitshift < 0) bitshift = 0;
-		tbl_index = tbl_index | ip[i-1] << bitshift;
-	}
+	entry_ind = get_bitshift(ip, first_byte, bytes);
 
 	/* Number of bits covered in this step */
 	bits_covered = (uint8_t)((bytes+first_byte-1)*BYTE_SIZE);
@@ -487,7 +676,7 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
 	if (depth <= bits_covered) {
 		tbl_range = 1 << (bits_covered - depth);
 
-		for (i = tbl_index; i < (tbl_index + tbl_range); i++) {
+		for (i = entry_ind; i < (entry_ind + tbl_range); i++) {
 			if (!tbl[i].valid || (tbl[i].ext_entry == 0 &&
 					tbl[i].depth <= depth)) {
 
@@ -509,10 +698,15 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
 				 */
 				tbl8_gindex = tbl[i].lpm6_tbl8_gindex *
 						RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
-				expand_rule(lpm, tbl8_gindex, depth, next_hop);
+				expand_rule(lpm, tbl8_gindex, depth, depth,
+						next_hop, VALID);
 			}
 		}
 
+		/* update tbl8 rule reference counter */
+		if (tbl_ind != TBL24_IND && is_new_rule)
+			lpm->tbl8_hdrs[tbl_ind].ref_cnt++;
+
 		return 0;
 	}
 	/*
@@ -521,12 +715,24 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
 	 */
 	else {
 		/* If it's invalid a new tbl8 is needed */
-		if (!tbl[tbl_index].valid) {
-			if (lpm->next_tbl8 < lpm->number_tbl8s)
-				tbl8_gindex = (lpm->next_tbl8)++;
-			else
+		if (!tbl[entry_ind].valid) {
+			/* get a new table */
+			ret = tbl8_get(lpm, &tbl8_gindex);
+			if (ret != 0)
 				return -ENOSPC;
 
+			/* invalidate all new tbl8 entries */
+			tbl8_group_start = tbl8_gindex *
+					RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
+			memset(&lpm->tbl8[tbl8_group_start], 0,
+					  RTE_LPM6_TBL8_GROUP_NUM_ENTRIES);
+
+			/* init the new table's header:
+			 *   save the reference to the owner table
+			 */
+			init_tbl8_header(lpm, tbl8_gindex, tbl_ind, entry_ind);
+
+			/* reference to a new tbl8 */
 			struct rte_lpm6_tbl_entry new_tbl_entry = {
 				.lpm6_tbl8_gindex = tbl8_gindex,
 				.depth = 0,
@@ -535,17 +741,20 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
 				.ext_entry = 1,
 			};
 
-			tbl[tbl_index] = new_tbl_entry;
+			tbl[entry_ind] = new_tbl_entry;
+
+			/* update the current table's reference counter */
+			if (tbl_ind != TBL24_IND)
+				lpm->tbl8_hdrs[tbl_ind].ref_cnt++;
 		}
 		/*
-		 * If it's valid but not extended the rule that was stored *
+		 * If it's valid but not extended the rule that was stored
 		 * here needs to be moved to the next table.
 		 */
-		else if (tbl[tbl_index].ext_entry == 0) {
-			/* Search for free tbl8 group. */
-			if (lpm->next_tbl8 < lpm->number_tbl8s)
-				tbl8_gindex = (lpm->next_tbl8)++;
-			else
+		else if (tbl[entry_ind].ext_entry == 0) {
+			/* get a new tbl8 index */
+			ret = tbl8_get(lpm, &tbl8_gindex);
+			if (ret != 0)
 				return -ENOSPC;
 
 			tbl8_group_start = tbl8_gindex *
@@ -553,13 +762,22 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
 			tbl8_group_end = tbl8_group_start +
 					RTE_LPM6_TBL8_GROUP_NUM_ENTRIES;
 
+			struct rte_lpm6_tbl_entry tbl_entry = {
+				.next_hop = tbl[entry_ind].next_hop,
+				.depth = tbl[entry_ind].depth,
+				.valid = VALID,
+				.valid_group = VALID,
+				.ext_entry = 0
+			};
+
 			/* Populate new tbl8 with tbl value. */
-			for (i = tbl8_group_start; i < tbl8_group_end; i++) {
-				lpm->tbl8[i].valid = VALID;
-				lpm->tbl8[i].depth = tbl[tbl_index].depth;
-				lpm->tbl8[i].next_hop = tbl[tbl_index].next_hop;
-				lpm->tbl8[i].ext_entry = 0;
-			}
+			for (i = tbl8_group_start; i < tbl8_group_end; i++)
+				lpm->tbl8[i] = tbl_entry;
+
+			/* init the new table's header:
+			 *   save the reference to the owner table
+			 */
+			init_tbl8_header(lpm, tbl8_gindex, tbl_ind, entry_ind);
 
 			/*
 			 * Update tbl entry to point to new tbl8 entry. Note: The
@@ -574,11 +792,16 @@ add_step(struct rte_lpm6 *lpm, struct rte_lpm6_tbl_entry *tbl,
 				.ext_entry = 1,
 			};
 
-			tbl[tbl_index] = new_tbl_entry;
+			tbl[entry_ind] = new_tbl_entry;
+
+			/* update the current table's reference counter */
+			if (tbl_ind != TBL24_IND)
+				lpm->tbl8_hdrs[tbl_ind].ref_cnt++;
 		}
 
-		*tbl_next = &(lpm->tbl8[tbl[tbl_index].lpm6_tbl8_gindex *
-				RTE_LPM6_TBL8_GROUP_NUM_ENTRIES]);
+		*next_tbl_ind = tbl[entry_ind].lpm6_tbl8_gindex;
+		*next_tbl = &(lpm->tbl8[*next_tbl_ind *
+				  RTE_LPM6_TBL8_GROUP_NUM_ENTRIES]);
 	}
 
 	return 1;
@@ -595,13 +818,56 @@ rte_lpm6_add_v20(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 }
 VERSION_SYMBOL(rte_lpm6_add, _v20, 2.0);
 
+
+/*
+ * Simulate adding a route to LPM
+ *
+ *	Returns:
+ *    0 on success
+ *    -ENOSPC not enought tbl8 left
+ */
+static int
+simulate_add(struct rte_lpm6 *lpm, const uint8_t *masked_ip, uint8_t depth)
+{
+	struct rte_lpm6_tbl_entry *tbl;
+	struct rte_lpm6_tbl_entry *tbl_next = NULL;
+	int ret, i;
+
+	/* number of new tables needed for a step */
+	uint32_t need_tbl_nb;
+	/* total number of new tables needed */
+	uint32_t total_need_tbl_nb;
+
+	/* Inspect the first three bytes through tbl24 on the first step. */
+	ret = simulate_add_step(lpm, lpm->tbl24, &tbl_next, masked_ip,
+			ADD_FIRST_BYTE, 1, depth, &need_tbl_nb);
+	total_need_tbl_nb = need_tbl_nb;
+	/*
+	 * Inspect one by one the rest of the bytes until
+	 * the process is completed.
+	 */
+	for (i = ADD_FIRST_BYTE; i < RTE_LPM6_IPV6_ADDR_SIZE && ret == 1; i++) {
+		tbl = tbl_next;
+		ret = simulate_add_step(lpm, tbl, &tbl_next, masked_ip, 1,
+				(uint8_t)(i+1), depth, &need_tbl_nb);
+		total_need_tbl_nb += need_tbl_nb;
+	}
+
+	if (tbl8_available(lpm) < total_need_tbl_nb)
+		/* not enought tbl8 to add a rule */
+		return -ENOSPC;
+
+	return 0;
+}
+
 int
 rte_lpm6_add_v1705(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 		uint32_t next_hop)
 {
 	struct rte_lpm6_tbl_entry *tbl;
 	struct rte_lpm6_tbl_entry *tbl_next = NULL;
-	int32_t ret;
+	/* init to avoid compiler warning */
+	uint32_t tbl_next_num = 123456;
 	int status;
 	uint8_t masked_ip[RTE_LPM6_IPV6_ADDR_SIZE];
 	int i;
@@ -614,21 +880,23 @@ rte_lpm6_add_v1705(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 	ip6_copy_addr(masked_ip, ip);
 	ip6_mask_addr(masked_ip, depth);
 
-	/* Add the rule to the rule table. */
-	ret = rule_add(lpm, masked_ip, depth, next_hop);
-	/* If there is no space available for new rule return error. */
+	/* Simulate adding a new route */
+	int ret = simulate_add(lpm, masked_ip, depth);
 	if (ret < 0)
 		return ret;
 
+	/* Add the rule to the rule table. */
+	int is_new_rule = rule_add(lpm, masked_ip, depth, next_hop);
+	/* If there is no space available for new rule return error. */
+	if (is_new_rule < 0)
+		return is_new_rule;
+
 	/* Inspect the first three bytes through tbl24 on the first step. */
 	tbl = lpm->tbl24;
-	status = add_step (lpm, tbl, &tbl_next, masked_ip, ADD_FIRST_BYTE, 1,
-			depth, next_hop);
-	if (status < 0) {
-		rte_lpm6_delete(lpm, masked_ip, depth);
-
-		return status;
-	}
+	status = add_step(lpm, tbl, TBL24_IND, &tbl_next, &tbl_next_num,
+			masked_ip, ADD_FIRST_BYTE, 1, depth, next_hop,
+			is_new_rule);
+	assert(status >= 0);
 
 	/*
 	 * Inspect one by one the rest of the bytes until
@@ -636,13 +904,10 @@ rte_lpm6_add_v1705(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
 	 */
 	for (i = ADD_FIRST_BYTE; i < RTE_LPM6_IPV6_ADDR_SIZE && status == 1; i++) {
 		tbl = tbl_next;
-		status = add_step (lpm, tbl, &tbl_next, masked_ip, 1, (uint8_t)(i+1),
-				depth, next_hop);
-		if (status < 0) {
-			rte_lpm6_delete(lpm, masked_ip, depth);
-
-			return status;
-		}
+		status = add_step(lpm, tbl, tbl_next_num, &tbl_next,
+				&tbl_next_num, masked_ip, 1, (uint8_t)(i+1),
+				depth, next_hop, is_new_rule);
+		assert(status >= 0);
 	}
 
 	return status;
@@ -717,9 +982,8 @@ rte_lpm6_lookup_v1705(const struct rte_lpm6 *lpm, uint8_t *ip,
 	uint32_t tbl24_index;
 
 	/* DEBUG: Check user input arguments. */
-	if ((lpm == NULL) || (ip == NULL) || (next_hop == NULL)) {
+	if ((lpm == NULL) || (ip == NULL) || (next_hop == NULL))
 		return -EINVAL;
-	}
 
 	first_byte = LOOKUP_FIRST_BYTE;
 	tbl24_index = (ip[0] << BYTES2_SIZE) | (ip[1] << BYTE_SIZE) | ip[2];
@@ -755,9 +1019,8 @@ rte_lpm6_lookup_bulk_func_v20(const struct rte_lpm6 *lpm,
 	int status;
 
 	/* DEBUG: Check user input arguments. */
-	if ((lpm == NULL) || (ips == NULL) || (next_hops == NULL)) {
+	if ((lpm == NULL) || (ips == NULL) || (next_hops == NULL))
 		return -EINVAL;
-	}
 
 	for (i = 0; i < n; i++) {
 		first_byte = LOOKUP_FIRST_BYTE;
@@ -900,62 +1163,22 @@ rule_delete(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth)
 	return ret;
 }
 
-/*
- * Deletes a rule
- */
-int
-rte_lpm6_delete(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth)
-{
-	uint8_t masked_ip[RTE_LPM6_IPV6_ADDR_SIZE];
-	int ret;
-
-	/*
-	 * Check input arguments.
-	 */
-	if ((lpm == NULL) || (depth < 1) || (depth > RTE_LPM6_MAX_DEPTH)) {
-		return -EINVAL;
-	}
-
-	/* Copy the IP and mask it to avoid modifying user's input data. */
-	ip6_copy_addr(masked_ip, ip);
-	ip6_mask_addr(masked_ip, depth);
-
-	/* Delete the rule from the rule table. */
-	ret = rule_delete(lpm, masked_ip, depth);
-	if (ret < 0)
-		return -ENOENT;
-
-	/*
-	 * Set all the table entries to 0 (ie delete every rule
-	 * from the data structure.
-	 */
-	lpm->next_tbl8 = 0;
-	memset(lpm->tbl24, 0, sizeof(lpm->tbl24));
-	memset(lpm->tbl8, 0, sizeof(lpm->tbl8[0])
-			* RTE_LPM6_TBL8_GROUP_NUM_ENTRIES * lpm->number_tbl8s);
-
-	/*
-	 * Add every rule again (except for the one that was removed from
-	 * the rules table).
-	 */
-	rebuild_lpm(lpm);
-
-	return 0;
-}
-
 /*
  * Deletes a group of rules
+ *
+ * Note that the function rebuilds the lpm table,
+ * rather than doing incremental updates like
+ * the regular delete function
  */
 int
 rte_lpm6_delete_bulk_func(struct rte_lpm6 *lpm,
-		uint8_t ips[][RTE_LPM6_IPV6_ADDR_SIZE], uint8_t *depths, unsigned n)
+		uint8_t ips[][RTE_LPM6_IPV6_ADDR_SIZE], uint8_t *depths,
+		unsigned n)
 {
 	uint8_t masked_ip[RTE_LPM6_IPV6_ADDR_SIZE];
 	unsigned i;
 
-	/*
-	 * Check input arguments.
-	 */
+	/* Check input arguments. */
 	if ((lpm == NULL) || (ips == NULL) || (depths == NULL))
 		return -EINVAL;
 
@@ -969,10 +1192,10 @@ rte_lpm6_delete_bulk_func(struct rte_lpm6 *lpm,
 	 * Set all the table entries to 0 (ie delete every rule
 	 * from the data structure.
 	 */
-	lpm->next_tbl8 = 0;
 	memset(lpm->tbl24, 0, sizeof(lpm->tbl24));
 	memset(lpm->tbl8, 0, sizeof(lpm->tbl8[0])
 			* RTE_LPM6_TBL8_GROUP_NUM_ENTRIES * lpm->number_tbl8s);
+	tbl8_pool_init(lpm);
 
 	/*
 	 * Add every rule again (except for the ones that were removed from
@@ -992,9 +1215,6 @@ rte_lpm6_delete_all(struct rte_lpm6 *lpm)
 	/* Zero used rules counter. */
 	lpm->used_rules = 0;
 
-	/* Zero next tbl8 index. */
-	lpm->next_tbl8 = 0;
-
 	/* Zero tbl24. */
 	memset(lpm->tbl24, 0, sizeof(lpm->tbl24));
 
@@ -1002,6 +1222,268 @@ rte_lpm6_delete_all(struct rte_lpm6 *lpm)
 	memset(lpm->tbl8, 0, sizeof(lpm->tbl8[0]) *
 			RTE_LPM6_TBL8_GROUP_NUM_ENTRIES * lpm->number_tbl8s);
 
+	/* init pool of free tbl8 indexes */
+	tbl8_pool_init(lpm);
+
 	/* Delete all rules form the rules table. */
 	rte_hash_reset(lpm->rules_tbl);
 }
+
+/*
+ * Convert a depth to a one byte long mask
+ *   Example: 4 will be converted to 0xF0
+ */
+static uint8_t __attribute__((pure))
+depth_to_mask_1b(uint8_t depth)
+{
+	/* To calculate a mask start with a 1 on the left hand side and right
+	 * shift while populating the left hand side with 1's
+	 */
+	return (signed char)0x80 >> (depth - 1);
+}
+
+/*
+ * Find a less specific rule
+ */
+static int
+rule_find_less_specific(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth,
+	struct rte_lpm6_rule *rule)
+{
+	int ret;
+	uint32_t next_hop;
+	uint8_t mask;
+	struct rte_lpm6_rule_key rule_key;
+
+	if (depth == 1)
+		return 0;
+
+	rule_key_init(&rule_key, ip, depth);
+
+	while (depth > 1) {
+		depth--;
+
+		/* each iteration zero one more bit of the key */
+		mask = depth & 7; /* depth % BYTE_SIZE */
+		if (mask > 0)
+			mask = depth_to_mask_1b(mask);
+
+		rule_key.depth = depth;
+		rule_key.ip[depth >> 3] &= mask;
+
+		ret = rule_find_with_key(lpm, &rule_key, &next_hop);
+		if (ret) {
+			rule->depth = depth;
+			ip6_copy_addr(rule->ip, rule_key.ip);
+			rule->next_hop = next_hop;
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Find range of tbl8 cells occupied by a rule
+ */
+static void
+rule_find_range(struct rte_lpm6 *lpm, const uint8_t *ip, uint8_t depth,
+		  struct rte_lpm6_tbl_entry **from,
+		  struct rte_lpm6_tbl_entry **to,
+		  uint32_t *out_tbl_ind)
+{
+	uint32_t ind;
+	uint32_t first_3bytes = (uint32_t)ip[0] << 16 | ip[1] << 8 | ip[2];
+
+	if (depth <= 24) {
+		/* rule is within the top level */
+		ind = first_3bytes;
+		*from = &lpm->tbl24[ind];
+		ind += (1 << (24 - depth)) - 1;
+		*to = &lpm->tbl24[ind];
+		*out_tbl_ind = TBL24_IND;
+	} else {
+		/* top level entry */
+		struct rte_lpm6_tbl_entry *tbl = &lpm->tbl24[first_3bytes];
+		assert(tbl->ext_entry == 1);
+		/* first tbl8 */
+		uint32_t tbl_ind = tbl->lpm6_tbl8_gindex;
+		tbl = &lpm->tbl8[tbl_ind *
+				RTE_LPM6_TBL8_GROUP_NUM_ENTRIES];
+		/* current ip byte, the top level is already behind */
+		uint8_t byte = 3;
+		/* minus top level */
+		depth -= 24;
+
+		/* interate through levels (tbl8s)
+		 * until we reach the last one
+		 */
+		while (depth > 8) {
+			tbl += ip[byte];
+			assert(tbl->ext_entry == 1);
+			/* go to the next level/tbl8 */
+			tbl_ind = tbl->lpm6_tbl8_gindex;
+			tbl = &lpm->tbl8[tbl_ind *
+					RTE_LPM6_TBL8_GROUP_NUM_ENTRIES];
+			byte += 1;
+			depth -= 8;
+		}
+
+		/* last level/tbl8 */
+		ind = ip[byte] & depth_to_mask_1b(depth);
+		*from = &tbl[ind];
+		ind += (1 << (8 - depth)) - 1;
+		*to = &tbl[ind];
+		*out_tbl_ind = tbl_ind;
+	}
+}
+
+/*
+ * Remove a table from the LPM tree
+ */
+static void
+remove_tbl(struct rte_lpm6 *lpm, struct rte_lpm_tbl8_hdr *tbl_hdr,
+		  uint32_t tbl_ind, struct rte_lpm6_rule *lsp_rule)
+{
+	struct rte_lpm6_tbl_entry *owner_entry;
+
+	if (tbl_hdr->owner_tbl_ind == TBL24_IND)
+		owner_entry = &lpm->tbl24[tbl_hdr->owner_entry_ind];
+	else {
+		uint32_t owner_tbl_ind = tbl_hdr->owner_tbl_ind;
+		owner_entry = &lpm->tbl8[
+			owner_tbl_ind * RTE_LPM6_TBL8_GROUP_NUM_ENTRIES +
+			tbl_hdr->owner_entry_ind];
+
+		struct rte_lpm_tbl8_hdr *owner_tbl_hdr =
+			&lpm->tbl8_hdrs[owner_tbl_ind];
+		if (--owner_tbl_hdr->ref_cnt == 0)
+			remove_tbl(lpm, owner_tbl_hdr, owner_tbl_ind, lsp_rule);
+	}
+
+	assert(owner_entry->ext_entry == 1);
+
+	/* unlink the table */
+	if (lsp_rule != NULL) {
+		struct rte_lpm6_tbl_entry new_tbl_entry = {
+			.next_hop = lsp_rule->next_hop,
+			.depth = lsp_rule->depth,
+			.valid = VALID,
+			.valid_group = VALID,
+			.ext_entry = 0
+		};
+
+		*owner_entry = new_tbl_entry;
+	} else {
+		struct rte_lpm6_tbl_entry new_tbl_entry = {
+			.next_hop = 0,
+			.depth = 0,
+			.valid = INVALID,
+			.valid_group = INVALID,
+			.ext_entry = 0
+		};
+
+		*owner_entry = new_tbl_entry;
+	}
+
+	/* return the table to the pool */
+	tbl8_put(lpm, tbl_ind);
+}
+
+/*
+ * Deletes a rule
+ */
+int
+rte_lpm6_delete(struct rte_lpm6 *lpm, uint8_t *ip, uint8_t depth)
+{
+	uint8_t masked_ip[RTE_LPM6_IPV6_ADDR_SIZE];
+	struct rte_lpm6_rule lsp_rule_obj;
+	struct rte_lpm6_rule *lsp_rule;
+	int ret;
+	uint32_t tbl_ind;
+	struct rte_lpm6_tbl_entry *from, *to;
+
+	/* Check input arguments. */
+	if ((lpm == NULL) || (depth < 1) || (depth > RTE_LPM6_MAX_DEPTH))
+		return -EINVAL;
+
+	/* Copy the IP and mask it to avoid modifying user's input data. */
+	ip6_copy_addr(masked_ip, ip);
+	ip6_mask_addr(masked_ip, depth);
+
+	/* Delete the rule from the rule table. */
+	ret = rule_delete(lpm, masked_ip, depth);
+	if (ret < 0)
+		return -ENOENT;
+
+	/* find rule cells */
+	rule_find_range(lpm, masked_ip, depth, &from, &to, &tbl_ind);
+
+	/* find a less specific rule (a rule with smaller depth)
+	 * note: masked_ip will be modified, don't use it anymore
+	 */
+	ret = rule_find_less_specific(lpm, masked_ip, depth,
+			&lsp_rule_obj);
+	lsp_rule = ret ? &lsp_rule_obj : NULL;
+
+	/* decrement the table rule counter,
+	 * note that tbl24 doesn't have a header
+	 */
+	if (tbl_ind != TBL24_IND) {
+		struct rte_lpm_tbl8_hdr *tbl_hdr = &lpm->tbl8_hdrs[tbl_ind];
+		if (--tbl_hdr->ref_cnt == 0) {
+			/* remove the table */
+			remove_tbl(lpm, tbl_hdr, tbl_ind, lsp_rule);
+			return 0;
+		}
+	}
+
+	/* iterate rule cells */
+	for (; from <= to; from++)
+		if (from->ext_entry == 1) {
+			/* reference to a more specific space
+			 * of the prefix/rule. Entries in a more
+			 * specific space that are not used by
+			 * a more specific prefix must be occupied
+			 * by the prefix
+			 */
+			if (lsp_rule != NULL)
+				expand_rule(lpm,
+					from->lpm6_tbl8_gindex *
+					RTE_LPM6_TBL8_GROUP_NUM_ENTRIES,
+					depth, lsp_rule->depth,
+					lsp_rule->next_hop, VALID);
+			else
+				/* since the prefix has no less specific prefix,
+				 * its more specific space must be invalidated
+				 */
+				expand_rule(lpm,
+					from->lpm6_tbl8_gindex *
+					RTE_LPM6_TBL8_GROUP_NUM_ENTRIES,
+					depth, 0, 0, INVALID);
+		} else if (from->depth == depth) {
+			/* entry is not a reference and belongs to the prefix */
+			if (lsp_rule != NULL) {
+				struct rte_lpm6_tbl_entry new_tbl_entry = {
+					.next_hop = lsp_rule->next_hop,
+					.depth = lsp_rule->depth,
+					.valid = VALID,
+					.valid_group = VALID,
+					.ext_entry = 0
+				};
+
+				*from = new_tbl_entry;
+			} else {
+				struct rte_lpm6_tbl_entry new_tbl_entry = {
+					.next_hop = 0,
+					.depth = 0,
+					.valid = INVALID,
+					.valid_group = INVALID,
+					.ext_entry = 0
+				};
+
+				*from = new_tbl_entry;
+			}
+		}
+
+	return 0;
+}
-- 
2.16.1.windows.1

Re: [dpdk-dev] [PATCH v6 2/2] librte_lpm: Improve performance of the delete and add functions

[Bruce Richardson]

On Tue, Jul 17, 2018 at 12:20:19PM +0300, Alex Kiselev wrote:
> librte_lpm: Improve lpm6 performance
> 
> There is no need to rebuild the whole LPM tree
> when a rule is deleted. This patch addresses this
> issue introducing new delete operation.
> 
> Signed-off-by: Alex Kiselev <alex@therouter.net>
> ---
>  lib/librte_lpm/rte_lpm6.c | 712 ++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 597 insertions(+), 115 deletions(-)
> 
As with patch 1, title could do with some rewording to make it clearer the
specific change and that is applies to lpm6 only.

Otherwise:
Acked-by: Bruce Richardson <bruce.richardson@intel.com>