简介

EFD（Elastic Flow Distributor）是利用完美散列（perfect hashing）实现的一个流分发库，具有以下优点：

1. 不需要存储key，查找性能不受key大小影响。
2. 目标/值（target/value）可以任意值。
3. 支持数百万量级的key。
4. 支持多核CPU性能扩展。

因此，一般可以用于实现在数据中心进行负载均衡流量分发的场景；具体可参考示例examples/server_node_efd

示例

API

源码

#include <rte_byteorder.h>
#include <rte_efd.h>

static void efd_test(void)
{
	unsigned int i;
	unsigned int num_flows = 4;
	unsigned int num_nodes = 2;
	int32_t ret;
	uint32_t ip_dst;
	uint8_t socket_id = rte_socket_id();
	uint64_t node_id;
	struct rte_efd_table *efd_table;
	void *key_ptrs;
	uint32_t ipv4_dst_ip;

	/* create table */
	efd_table = rte_efd_create("flow table", 4, sizeof(uint32_t), 1 << socket_id,	socket_id);
	if (efd_table == NULL)
		rte_exit(EXIT_FAILURE, "Problem creating the flow table\n");

	/* add flows in table */
	for (i = 0; i < num_flows; i++) {
		node_id = i % num_nodes + 1;
		ip_dst = rte_cpu_to_be_32(i);
		ret = rte_efd_update(efd_table, socket_id,
				(void *)&ip_dst, (efd_value_t)node_id);
		if (ret < 0)
			rte_exit(EXIT_FAILURE, "Unable to add entry %u in "
					"EFD table\n", i);
	}
	printf("EFD table: Adding 0x%x keys\n", num_flows);

	/* lookup flows in table */
	for (i = 0; i < num_flows+1; i++) {
		ipv4_dst_ip = rte_cpu_to_be_32(i);
		key_ptrs = &ipv4_dst_ip;
		ret = rte_efd_lookup(efd_table, socket_id, key_ptrs);
		if (ret == 0) {
			printf("EFD table: lookup keys %d not found\n", i);	
		} else {
			printf("EFD table: lookup keys %d to node:%d\n", i, ret);	
		}
	}	
}		

运行结果

EFD table: Adding 0x4 keys
EFD table: lookup keys 0 to node:1
EFD table: lookup keys 1 to node:2
EFD table: lookup keys 2 to node:1
EFD table: lookup keys 3 to node:2
EFD table: lookup keys 4 not found