6.1. Explanation¶
The following sections provide some explanation of the code.
6.1.1. Initializing¶
A manager thread of spp_vf initialize eal by rte_eal_init().
Then each of component threads are launched by
rte_eal_remote_launch().
/* spp_vf.c */
int ret_dpdk = rte_eal_init(argc, argv);
/* Start worker threads of classifier and forwarder */
unsigned int lcore_id = 0;
RTE_LCORE_FOREACH_SLAVE(lcore_id) {
rte_eal_remote_launch(slave_main, NULL, lcore_id);
}
6.1.2. Main function of slave thread¶
slave_main() is called from rte_eal_remote_launch().
It call spp_classifier_mac_do() or spp_forward() depending
on the component command setting.
spp_classifier_mac_do() provides function for classifier,
and spp_forward() provides forwarder and merger.
/* spp_vf.c */
RTE_LOG(INFO, APP, "Core[%d] Start.\n", lcore_id);
set_core_status(lcore_id, SPP_CORE_IDLE);
while ((status = spp_get_core_status(lcore_id)) !=
SPP_CORE_STOP_REQUEST) {
if (status != SPP_CORE_FORWARD)
continue;
if (spp_check_core_index(lcore_id)) {
/* Setting with the flush command trigger. */
info->ref_index = (info->upd_index+1) %
SPP_INFO_AREA_MAX;
core = get_core_info(lcore_id);
}
for (cnt = 0; cnt < core->num; cnt++) {
if (spp_get_component_type(lcore_id) ==
SPP_COMPONENT_CLASSIFIER_MAC) {
/* Classifier loops inside the function. */
ret = spp_classifier_mac_do(core->id[cnt]);
break;
}
/*
* Forward / Merge returns at once.
* It is for processing multiple components.
*/
ret = spp_forward(core->id[cnt]);
if (unlikely(ret != 0))
break;
}
if (unlikely(ret != 0)) {
RTE_LOG(ERR, APP,
"Core[%d] Component Error. (id = %d)\n",
lcore_id, core->id[cnt]);
break;
}
}
set_core_status(lcore_id, SPP_CORE_STOP);
RTE_LOG(INFO, APP, "Core[%d] End.\n", lcore_id);
6.1.3. Data structure of classifier table¶
spp_classifier_mac_do() lookup following data defined in
classifier_mac.c,
when it process the packets.
Configuration of classifier is stored in the structure of
classified_data, classifier_mac_info and
classifier_mac_mng_info.
The classified_data has member variables for expressing the port
to be classified, classifier_mac_info has member variables
for determining the direction of packets such as hash tables.
Classifier manages two classifier_mac_info, one is for updating by
commands, the other is for looking up to process packets.
Then the classifier_mac_mng_info has
two(NUM_CLASSIFIER_MAC_INFO) classifier_mac_info
and index number for updating or reference.
/* classifier_mac.c */
/* classified data (destination port, target packets, etc) */
struct classified_data {
/* interface type (see "enum port_type") */
enum port_type iface_type;
/* index of ports handled by classifier */
int iface_no;
/* id for interface generated by spp_vf */
int iface_no_global;
/* port id generated by DPDK */
uint16_t port;
/* the number of packets in pkts[] */
uint16_t num_pkt;
/* packet array to be classified */
struct rte_mbuf *pkts[MAX_PKT_BURST];
};
/* classifier information */
struct classifier_mac_info {
/* component name */
char name[SPP_NAME_STR_LEN];
/* hash table keeps classifier_table */
struct rte_hash *classifier_table;
/* number of valid classification */
int num_active_classified;
/* index of valid classification */
int active_classifieds[RTE_MAX_ETHPORTS];
/* index of default classification */
int default_classified;
/* number of transmission ports */
int n_classified_data_tx;
/* receive port handled by classifier */
struct classified_data classified_data_rx;
/* transmission ports handled by classifier */
struct classified_data classified_data_tx[RTE_MAX_ETHPORTS];
};
/* classifier management information */
struct classifier_mac_mng_info {
/* classifier information */
struct classifier_mac_info info[NUM_CLASSIFIER_MAC_INFO];
/* Reference index number for classifier information */
volatile int ref_index;
/* Update index number for classifier information */
volatile int upd_index;
};
6.1.4. Packet processing in classifier¶
In spp_classifier_mac_do(), it receives packets from rx port and
send them to destinations with classify_packet().
classifier_info is an argument of classify_packet() and is used
to decide the destinations.
/* classifier_mac.c */
while (likely(spp_get_core_status(lcore_id) == SPP_CORE_FORWARD) &&
likely(spp_check_core_index(lcore_id) == 0)) {
/* change index of update side */
change_update_index(classifier_mng_info, id);
/* decide classifier information of the current cycle */
classifier_info = classifier_mng_info->info +
classifier_mng_info->ref_index;
classified_data_rx = &classifier_info->classified_data_rx;
classified_data_tx = classifier_info->classified_data_tx;
/* drain tx packets, if buffer is not filled for interval */
cur_tsc = rte_rdtsc();
if (unlikely(cur_tsc - prev_tsc > drain_tsc)) {
for (i = 0; i < classifier_info->n_classified_data_tx;
i++) {
if (likely(classified_data_tx[i].num_pkt == 0))
continue;
RTE_LOG(DEBUG, SPP_CLASSIFIER_MAC,
"transmit packets (drain). "
"index=%d, "
"num_pkt=%hu, "
"interval=%lu\n",
i,
classified_data_tx[i].num_pkt,
cur_tsc - prev_tsc);
transmit_packet(&classified_data_tx[i]);
}
prev_tsc = cur_tsc;
}
if (classified_data_rx->iface_type == UNDEF)
continue;
/* retrieve packets */
n_rx = rte_eth_rx_burst(classified_data_rx->port, 0,
rx_pkts, MAX_PKT_BURST);
if (unlikely(n_rx == 0))
continue;
#ifdef SPP_RINGLATENCYSTATS_ENABLE
if (classified_data_rx->iface_type == RING)
spp_ringlatencystats_calculate_latency(
classified_data_rx->iface_no,
rx_pkts, n_rx);
#endif
/* classify and transmit (filled) */
classify_packet(rx_pkts, n_rx, classifier_info,
classified_data_tx);
}
6.1.5. Classifying the packets¶
classify_packet() uses hash function of DPDK to determine
destination.
Hash has MAC address as Key, it retrieves destination information
from destination MAC address in the packet.
for (i = 0; i < n_rx; i++) {
eth = rte_pktmbuf_mtod(rx_pkts[i], struct ether_hdr *);
/* find in table (by destination mac address)*/
ret = rte_hash_lookup_data(classifier_info->classifier_table,
(const void *)ð->d_addr, &lookup_data);
if (ret < 0) {
/* L2 multicast(include broadcast) ? */
if (unlikely(is_multicast_ether_addr(ð->d_addr))) {
RTE_LOG(DEBUG, SPP_CLASSIFIER_MAC,
"multicast mac address.\n");
handle_l2multicast_packet(rx_pkts[i],
classifier_info,
classified_data);
continue;
}
/* if no default, drop packet */
if (unlikely(classifier_info->default_classified ==
-1)) {
ether_format_addr(mac_addr_str,
sizeof(mac_addr_str),
ð->d_addr);
RTE_LOG(ERR, SPP_CLASSIFIER_MAC,
"unknown mac address. "
"ret=%d, mac_addr=%s\n",
ret, mac_addr_str);
rte_pktmbuf_free(rx_pkts[i]);
continue;
}
/* to default classified */
RTE_LOG(DEBUG, SPP_CLASSIFIER_MAC,
"to default classified.\n");
lookup_data = (void *)(long)classifier_info->
default_classified;
}
/*
* set mbuf pointer to tx buffer
* and transmit packet, if buffer is filled
*/
push_packet(rx_pkts[i], classified_data + (long)lookup_data);
}
6.1.6. Packet processing in forwarder and merger¶
Configuration data for forwarder and merger is stored as structured
tables forward_rxtx, forward_path and forward_info.
The forward_rxtx has two member variables for expressing the port
to be sent(tx) and to be receive(rx),
forward_path has member variables for expressing the data path.
Like classifier_mac_info, forward_info has two tables,
one is for updating by commands, the other is for looking up to process
packets.
/* spp_forward.c */
/* A set of port info of rx and tx */
struct forward_rxtx {
struct spp_port_info rx; /* rx port */
struct spp_port_info tx; /* tx port */
};
/* Information on the path used for forward. */
struct forward_path {
char name[SPP_NAME_STR_LEN]; /* component name */
volatile enum spp_component_type type;
/* component type */
int num; /* number of receive ports */
struct forward_rxtx ports[RTE_MAX_ETHPORTS];
/* port used for transfer */
};
/* Information for forward. */
struct forward_info {
volatile int ref_index; /* index to reference area */
volatile int upd_index; /* index to update area */
struct forward_path path[SPP_INFO_AREA_MAX];
/* Information of data path */
};
6.1.7. Forward and merge the packets¶
spp_forward() defined in spp_forward.c is a main function
for both forwarder and merger.
spp_forward() simply passes packet received from rx port to
tx port of the pair.
/* spp_forward.c */
for (cnt = 0; cnt < num; cnt++) {
rx = &path->ports[cnt].rx;
tx = &path->ports[cnt].tx;
/* Receive packets */
nb_rx = rte_eth_rx_burst(
rx->dpdk_port, 0, bufs, MAX_PKT_BURST);
if (unlikely(nb_rx == 0))
continue;
#ifdef SPP_RINGLATENCYSTATS_ENABLE
if (rx->iface_type == RING)
spp_ringlatencystats_calculate_latency(
rx->iface_no,
bufs, nb_rx);
if (tx->iface_type == RING)
spp_ringlatencystats_add_time_stamp(
tx->iface_no,
bufs, nb_rx);
#endif /* SPP_RINGLATENCYSTATS_ENABLE */
/* Send packets */
if (tx->dpdk_port >= 0)
nb_tx = rte_eth_tx_burst(
tx->dpdk_port, 0, bufs, nb_rx);
/* Discard remained packets to release mbuf */
if (unlikely(nb_tx < nb_rx)) {
for (buf = nb_tx; buf < nb_rx; buf++)
rte_pktmbuf_free(bufs[buf]);
}
}
6.1.8. L2 Multicast Support¶
SPP_VF also supports multicast for resolving ARP requests.
It is implemented as handle_l2multicast_packet() and called from
classify_packet() for incoming multicast packets.
/* classify_packet() in classifier_mac.c */
/* L2 multicast(include broadcast) ? */
if (unlikely(is_multicast_ether_addr(ð->d_addr))) {
RTE_LOG(DEBUG, SPP_CLASSIFIER_MAC,
"multicast mac address.\n");
handle_l2multicast_packet(rx_pkts[i],
classifier_info,
classified_data);
continue;
}
For distributing multicast packet, it is cloned with
rte_mbuf_refcnt_update().
/* classifier_mac.c */
/* handle L2 multicast(include broadcast) packet */
static inline void
handle_l2multicast_packet(struct rte_mbuf *pkt,
struct classifier_mac_info *classifier_info,
struct classified_data *classified_data)
{
int i;
if (unlikely(classifier_info->num_active_classified == 0)) {
RTE_LOG(ERR,
SPP_CLASSIFIER_MAC,
"No mac address.(l2 multicast packet)\n");
rte_pktmbuf_free(pkt);
return;
}
rte_mbuf_refcnt_update(pkt,
(classifier_info->num_active_classified - 1));
for (i = 0; i < classifier_info->num_active_classified; i++) {
push_packet(pkt, classified_data +
(long)classifier_info->active_classifieds[i]);
}
}