samples/bpf: Use recvfrom() in xdpsock/l2fwd

Start using recvfrom() the l2fwd scenario, instead of poll() which is
more expensive and need additional knobs for busy-polling.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20201130185205.196029-9-bjorn.topel@gmail.com

diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
index f90111b95b2ef78ca9c29c83bcd94fbf121e3edb..a1a3d6f02ba9d8acadc5e2408ba40ab6111a4c31 100644 (file)
--- a/samples/bpf/xdpsock_user.c
+++ b/samples/bpf/xdpsock_user.c
@@ -1098,8 +1098,7 @@ static void kick_tx(struct xsk_socket_info *xsk)
        exit_with_error(errno);
 }
 
-static inline void complete_tx_l2fwd(struct xsk_socket_info *xsk,
-                                    struct pollfd *fds)
+static inline void complete_tx_l2fwd(struct xsk_socket_info *xsk)
 {
        struct xsk_umem_info *umem = xsk->umem;
        u32 idx_cq = 0, idx_fq = 0;
@@ -1134,7 +1133,8 @@ static inline void complete_tx_l2fwd(struct xsk_socket_info *xsk,
                                exit_with_error(-ret);
                        if (xsk_ring_prod__needs_wakeup(&umem->fq)) {
                                xsk->app_stats.fill_fail_polls++;
-                               ret = poll(fds, num_socks, opt_timeout);
+                               recvfrom(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL,
+                                        NULL);
                        }
                        ret = xsk_ring_prod__reserve(&umem->fq, rcvd, &idx_fq);
                }
@@ -1331,19 +1331,19 @@ static void tx_only_all(void)
                complete_tx_only_all();
 }
 
-static void l2fwd(struct xsk_socket_info *xsk, struct pollfd *fds)
+static void l2fwd(struct xsk_socket_info *xsk)
 {
        unsigned int rcvd, i;
        u32 idx_rx = 0, idx_tx = 0;
        int ret;
 
-       complete_tx_l2fwd(xsk, fds);
+       complete_tx_l2fwd(xsk);
 
        rcvd = xsk_ring_cons__peek(&xsk->rx, opt_batch_size, &idx_rx);
        if (!rcvd) {
                if (xsk_ring_prod__needs_wakeup(&xsk->umem->fq)) {
                        xsk->app_stats.rx_empty_polls++;
-                       ret = poll(fds, num_socks, opt_timeout);
+                       recvfrom(xsk_socket__fd(xsk->xsk), NULL, 0, MSG_DONTWAIT, NULL, NULL);
                }
                return;
        }
@@ -1353,7 +1353,7 @@ static void l2fwd(struct xsk_socket_info *xsk, struct pollfd *fds)
        while (ret != rcvd) {
                if (ret < 0)
                        exit_with_error(-ret);
-               complete_tx_l2fwd(xsk, fds);
+               complete_tx_l2fwd(xsk);
                if (xsk_ring_prod__needs_wakeup(&xsk->tx)) {
                        xsk->app_stats.tx_wakeup_sendtos++;
                        kick_tx(xsk);
@@ -1388,22 +1388,20 @@ static void l2fwd_all(void)
        struct pollfd fds[MAX_SOCKS] = {};
        int i, ret;
 
-       for (i = 0; i < num_socks; i++) {
-               fds[i].fd = xsk_socket__fd(xsks[i]->xsk);
-               fds[i].events = POLLOUT | POLLIN;
-       }
-
        for (;;) {
                if (opt_poll) {
-                       for (i = 0; i < num_socks; i++)
+                       for (i = 0; i < num_socks; i++) {
+                               fds[i].fd = xsk_socket__fd(xsks[i]->xsk);
+                               fds[i].events = POLLOUT | POLLIN;
                                xsks[i]->app_stats.opt_polls++;
+                       }
                        ret = poll(fds, num_socks, opt_timeout);
                        if (ret <= 0)
                                continue;
                }
 
                for (i = 0; i < num_socks; i++)
-                       l2fwd(xsks[i], fds);
+                       l2fwd(xsks[i]);
 
                if (benchmark_done)
                        break;