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net/af_xdp: use recvfrom only if busy polling enabled

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The recvfrom() syscall is only supported by AF_XDP sockets since
kernel 5.11. Only use it if busy polling is configured. We can
assume a kernel >= 5.11 is in use if busy polling is configured
so we can safely call recvfrom() in that case.

Fixes: 63e8989fe5 ("net/af_xdp: use recvfrom instead of poll syscall")

Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
This commit is contained in:
Ciara Loftus 2021-04-20 09:44:31 +01:00 committed by Ferruh Yigit
parent 2aa51cdd55
commit b42cffab05
2 changed files with 25 additions and 13 deletions
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28
drivers/net/af_xdp/compat.h
View File

@ -4,6 +4,7 @@
#include <bpf/xsk.h>
#include <linux/version.h>
#include <poll.h>
#if KERNEL_VERSION(5, 10, 0) <= LINUX_VERSION_CODE && \
defined(RTE_LIBRTE_AF_XDP_PMD_SHARED_UMEM)
@ -41,10 +42,22 @@ create_shared_socket(struct xsk_socket **xsk_ptr __rte_unused,
#endif
#ifdef XDP_USE_NEED_WAKEUP
static int
rx_syscall_needed(struct xsk_ring_prod *q, uint32_t busy_budget)
static void
rx_syscall_handler(struct xsk_ring_prod *q, uint32_t busy_budget,
struct pollfd *fds, struct xsk_socket *xsk)
{
return xsk_ring_prod__needs_wakeup(q) | busy_budget;
/* we can assume a kernel >= 5.11 is in use if busy polling is enabled
* and thus we can safely use the recvfrom() syscall which is only
* supported for AF_XDP sockets in kernels >= 5.11.
*/
if (busy_budget) {
(void)recvfrom(xsk_socket__fd(xsk), NULL, 0,
MSG_DONTWAIT, NULL, NULL);
return;
}
if (xsk_ring_prod__needs_wakeup(q))
(void)poll(fds, 1, 1000);
}
static int
tx_syscall_needed(struct xsk_ring_prod *q)
@ -52,10 +65,13 @@ tx_syscall_needed(struct xsk_ring_prod *q)
return xsk_ring_prod__needs_wakeup(q);
}
#else
static int
rx_syscall_needed(struct xsk_ring_prod *q __rte_unused, uint32_t busy_budget)
static void
rx_syscall_handler(struct xsk_ring_prod *q __rte_unused, uint32_t busy_budget,
struct pollfd *fds __rte_unused, struct xsk_socket *xsk)
{
return busy_budget;
if (busy_budget)
(void)recvfrom(xsk_socket__fd(xsk), NULL, 0,
MSG_DONTWAIT, NULL, NULL);
}
static int
tx_syscall_needed(struct xsk_ring_prod *q __rte_unused)

10
drivers/net/af_xdp/rte_eth_af_xdp.c
View File

@ -5,7 +5,6 @@
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <poll.h>
#include <netinet/in.h>
#include <net/if.h>
#include <sys/socket.h>
@ -273,10 +272,8 @@ af_xdp_rx_zc(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
nb_pkts = xsk_ring_cons__peek(rx, nb_pkts, &idx_rx);
if (nb_pkts == 0) {
if (rx_syscall_needed(&rxq->fq, rxq->busy_budget))
(void)recvfrom(xsk_socket__fd(rxq->xsk), NULL, 0,
MSG_DONTWAIT, NULL, NULL);
rx_syscall_handler(&rxq->fq, rxq->busy_budget, &rxq->fds[0],
rxq->xsk);
return 0;
}
@ -346,8 +343,7 @@ af_xdp_rx_cp(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
if (nb_pkts == 0) {
#if defined(XDP_USE_NEED_WAKEUP)
if (xsk_ring_prod__needs_wakeup(fq))
(void)recvfrom(xsk_socket__fd(rxq->xsk), NULL, 0,
MSG_DONTWAIT, NULL, NULL);
(void)poll(rxq->fds, 1, 1000);
#endif
return 0;
}