This patch enables busy-poll support for AF_XDP pmd. With busy-poll, the
kernel driver is executed in process context by calling the poll() syscall.
The main advantage of busy-poll feature is that all processing occurs on a
single core. This eliminates the core-to-core cache transfers that occur
between the application and the softirqd processing on another core.
The drawback of busy-poll is that it will downgrade the max throughput due
to syscall, but from a per-core perspective, the performance is better as
normal mode runs on two cores and busy-poll only runs on a single core.
Signed-off-by: Xiaolong Ye <xiaolong...@intel.com>
---
doc/guides/nics/af_xdp.rst | 1 +
drivers/net/af_xdp/rte_eth_af_xdp.c | 48 ++++++++++++++++++++++++++---
2 files changed, 45 insertions(+), 4 deletions(-)
diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
index 18defcda3..e42065170 100644
--- a/doc/guides/nics/af_xdp.rst
+++ b/doc/guides/nics/af_xdp.rst
@@ -29,6 +29,7 @@ The following options can be provided to set up an af_xdp
port in DPDK.
* ``iface`` - name of the Kernel interface to attach to (required);
* ``start_queue`` - starting netdev queue id (optional, default 0);
* ``queue_count`` - total netdev queue number (optional, default 1);
+* ``busy_poll_size`` - busy poll batch size (optional, default 0);
* ``pmd_zero_copy`` - enable zero copy or not (optional, default 0);
Prerequisites
diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c
b/drivers/net/af_xdp/rte_eth_af_xdp.c
index 9a4510701..1e46a4ef4 100644
--- a/drivers/net/af_xdp/rte_eth_af_xdp.c
+++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
@@ -6,6 +6,7 @@
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
+#include <poll.h>
#include <net/if.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
@@ -72,6 +73,7 @@ struct xsk_umem_info {
struct rte_ring *buf_ring;
const struct rte_memzone *mz;
int pmd_zc;
+ int busy_poll;
};
struct rx_stats {
@@ -114,6 +116,7 @@ struct pmd_internals {
int queue_cnt;
int pmd_zc;
+ int busy_poll_size;
struct ether_addr eth_addr;
struct xsk_umem_info *umem;
struct rte_mempool *mb_pool_share;
@@ -126,12 +129,14 @@ struct pmd_internals {
#define ETH_AF_XDP_START_QUEUE_ARG "start_queue"
#define ETH_AF_XDP_QUEUE_COUNT_ARG "queue_count"
#define ETH_AF_XDP_PMD_ZC_ARG "pmd_zero_copy"
+#define ETH_AF_XDP_BUSY_POLL_SIZE_ARG "busy_poll_size"
static const char * const valid_arguments[] = {
ETH_AF_XDP_IFACE_ARG,
ETH_AF_XDP_START_QUEUE_ARG,
ETH_AF_XDP_QUEUE_COUNT_ARG,
ETH_AF_XDP_PMD_ZC_ARG,
+ ETH_AF_XDP_BUSY_POLL_SIZE_ARG,
NULL
};
@@ -191,6 +196,7 @@ eth_af_xdp_rx(void *queue, struct rte_mbuf **bufs, uint16_t
nb_pkts)
struct xsk_ring_cons *rx = &rxq->rx;
struct xsk_umem_info *umem = rxq->umem;
struct xsk_ring_prod *fq = &umem->fq;
+ struct pollfd pfds[1];
uint32_t idx_rx = 0;
uint32_t free_thresh = fq->size >> 1;
int pmd_zc = umem->pmd_zc;
@@ -199,6 +205,15 @@ eth_af_xdp_rx(void *queue, struct rte_mbuf **bufs,
uint16_t nb_pkts)
unsigned long rx_bytes = 0;
int rcvd, i;
+ if (umem->busy_poll) {
+ memset(pfds, 0, sizeof(pfds));
+ pfds[0].fd = xsk_socket__fd(rxq->xsk);
+ pfds[0].events = POLLIN;
+
+ if (poll(pfds, 1, 0) <= 0)
+ return 0;
+ }
+
nb_pkts = RTE_MIN(nb_pkts, ETH_AF_XDP_RX_BATCH_SIZE);
if (unlikely(rte_pktmbuf_alloc_bulk(rxq->mb_pool, mbufs, nb_pkts) != 0))
@@ -305,12 +320,23 @@ eth_af_xdp_tx(void *queue, struct rte_mbuf **bufs,
uint16_t nb_pkts)
struct pkt_tx_queue *txq = queue;
struct xsk_umem_info *umem = txq->pair->umem;
struct rte_mbuf *mbuf;
+ struct pollfd pfds[1];
int pmd_zc = umem->pmd_zc;
void *addrs[ETH_AF_XDP_TX_BATCH_SIZE];
unsigned long tx_bytes = 0;
int i;
uint32_t idx_tx;
+ if (umem->busy_poll) {
+ memset(pfds, 0, sizeof(pfds));
+ pfds[0].fd = xsk_socket__fd(txq->pair->xsk);
+ pfds[0].events = POLLOUT;
+ if (poll(pfds, 1, 0) <= 0)
+ return 0;
+ if (!(pfds[0].revents & POLLOUT))
+ return 0;
+ }
+
nb_pkts = RTE_MIN(nb_pkts, ETH_AF_XDP_TX_BATCH_SIZE);
pull_umem_cq(umem, nb_pkts);
@@ -615,6 +641,7 @@ xsk_configure(struct pmd_internals *internals, struct
pkt_rx_queue *rxq,
cfg.rx_size = ring_size;
cfg.tx_size = ring_size;
cfg.libbpf_flags = 0;
+ cfg.busy_poll = internals->busy_poll_size;
cfg.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
cfg.bind_flags = 0;
ret = xsk_socket__create(&rxq->xsk, internals->if_name,
@@ -680,10 +707,14 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
internals->umem = rxq->umem;
internals->umem->pmd_zc = internals->pmd_zc;
+ internals->umem->busy_poll = internals->busy_poll_size ? 1 : 0;
if (internals->umem->pmd_zc)
AF_XDP_LOG(INFO, "Zero copy between umem and mbuf enabled.\n");
+ if (internals->umem->busy_poll)
+ AF_XDP_LOG(INFO, "Busy poll enabled.\n");
+
dev->data->rx_queues[rx_queue_id] = rxq;
return 0;
@@ -818,7 +849,7 @@ parse_name_arg(const char *key __rte_unused,
static int
parse_parameters(struct rte_kvargs *kvlist, char *if_name, int *start_queue,
- int *queue_cnt, int *pmd_zc)
+ int *queue_cnt, int *pmd_zc, int *busy_poll_size)
{
int ret;
@@ -844,6 +875,11 @@ parse_parameters(struct rte_kvargs *kvlist, char *if_name,
int *start_queue,
if (ret < 0)
goto free_kvlist;
+ ret = rte_kvargs_process(kvlist, ETH_AF_XDP_BUSY_POLL_SIZE_ARG,
+ &parse_integer_arg, busy_poll_size);
+ if (ret < 0)
+ goto free_kvlist;
+
free_kvlist:
rte_kvargs_free(kvlist);
return ret;
@@ -881,7 +917,8 @@ get_iface_info(const char *if_name,
static struct rte_eth_dev *
init_internals(struct rte_vdev_device *dev, const char *if_name,
- int start_queue_idx, int queue_cnt, int pmd_zc)
+ int start_queue_idx, int queue_cnt, int pmd_zc,
+ int busy_poll_size)
{
const char *name = rte_vdev_device_name(dev);
const unsigned int numa_node = dev->device.numa_node;
@@ -897,6 +934,7 @@ init_internals(struct rte_vdev_device *dev, const char
*if_name,
internals->start_queue_idx = start_queue_idx;
internals->queue_cnt = queue_cnt;
internals->pmd_zc = pmd_zc;
+ internals->busy_poll_size = busy_poll_size;
strlcpy(internals->if_name, if_name, IFNAMSIZ);
for (i = 0; i < queue_cnt; i++) {
@@ -941,6 +979,7 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
struct rte_eth_dev *eth_dev = NULL;
const char *name;
int pmd_zc = 0;
+ int busy_poll_size = 0;
AF_XDP_LOG(INFO, "Initializing pmd_af_xdp for %s\n",
rte_vdev_device_name(dev));
@@ -968,7 +1007,7 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
dev->device.numa_node = rte_socket_id();
if (parse_parameters(kvlist, if_name, &xsk_start_queue_idx,
- &xsk_queue_cnt, &pmd_zc) < 0) {
+ &xsk_queue_cnt, &pmd_zc, &busy_poll_size) < 0) {
AF_XDP_LOG(ERR, "Invalid kvargs value\n");
return -EINVAL;
}
@@ -979,7 +1018,7 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
}
eth_dev = init_internals(dev, if_name, xsk_start_queue_idx,
- xsk_queue_cnt, pmd_zc);
+ xsk_queue_cnt, pmd_zc, busy_poll_size);
if (eth_dev == NULL) {
AF_XDP_LOG(ERR, "Failed to init internals\n");
return -1;
@@ -1023,6 +1062,7 @@ RTE_PMD_REGISTER_PARAM_STRING(net_af_xdp,
"iface=<string> "
"start_queue=<int> "
"queue_count=<int> "
+ "busy_poll_size=<int> "
"pmd_zero_copy=<0|1>");
RTE_INIT(af_xdp_init_log)
--
2.17.1
