xsk: Change the default frame size to 4096 and allow controlling it

The typical XDP memory scheme is one packet per page. Change the AF_XDP
frame size in libbpf to 4096, which is the page size on x86, to allow
libbpf to be used with the drivers with the packet-per-page scheme.

Add a command line option -f to xdpsock to allow to specify a custom
frame size.

Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 28 insertions, 16 deletions

diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
index 0f5eb0d7f2df..93eaaf7239b2 100644
--- a/samples/bpf/xdpsock_user.c
+++ b/samples/bpf/xdpsock_user.c
@@ -68,6 +68,7 @@ static int opt_queue;
 static int opt_poll;
 static int opt_interval = 1;
 static u32 opt_xdp_bind_flags;
+static int opt_xsk_frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE;
 static __u32 prog_id;
 
 struct xsk_umem_info {
@@ -276,6 +277,12 @@ static size_t gen_eth_frame(struct xsk_umem_info *umem, u64 addr)
 static struct xsk_umem_info *xsk_configure_umem(void *buffer, u64 size)
 {
         struct xsk_umem_info *umem;
+        struct xsk_umem_config cfg = {
+                .fill_size = XSK_RING_PROD__DEFAULT_NUM_DESCS,
+                .comp_size = XSK_RING_CONS__DEFAULT_NUM_DESCS,
+                .frame_size = opt_xsk_frame_size,
+                .frame_headroom = XSK_UMEM__DEFAULT_FRAME_HEADROOM,
+        };
         int ret;
 
         umem = calloc(1, sizeof(*umem));
@@ -283,7 +290,7 @@ static struct xsk_umem_info *xsk_configure_umem(void *buffer, u64 size)
                 exit_with_error(errno);
 
         ret = xsk_umem__create(&umem->umem, buffer, size, &umem->fq, &umem->cq,
-                               NULL);
+                               &cfg);
         if (ret)
                 exit_with_error(-ret);
 
@@ -323,11 +330,9 @@ static struct xsk_socket_info *xsk_configure_socket(struct xsk_umem_info *umem)
                                      &idx);
         if (ret != XSK_RING_PROD__DEFAULT_NUM_DESCS)
                 exit_with_error(-ret);
-        for (i = 0;
-             i < XSK_RING_PROD__DEFAULT_NUM_DESCS *
-                     XSK_UMEM__DEFAULT_FRAME_SIZE;
-             i += XSK_UMEM__DEFAULT_FRAME_SIZE)
-                *xsk_ring_prod__fill_addr(&xsk->umem->fq, idx++) = i;
+        for (i = 0; i < XSK_RING_PROD__DEFAULT_NUM_DESCS; i++)
+                *xsk_ring_prod__fill_addr(&xsk->umem->fq, idx++) =
+                        i * opt_xsk_frame_size;
         xsk_ring_prod__submit(&xsk->umem->fq,
                               XSK_RING_PROD__DEFAULT_NUM_DESCS);
 
@@ -346,6 +351,7 @@ static struct option long_options[] = {
         {"interval", required_argument, 0, 'n'},
         {"zero-copy", no_argument, 0, 'z'},
         {"copy", no_argument, 0, 'c'},
+        {"frame-size", required_argument, 0, 'f'},
         {0, 0, 0, 0}
 };
 
@@ -365,8 +371,9 @@ static void usage(const char *prog)
                 "  -n, --interval=n     Specify statistics update interval (default 1 sec).\n"
                 "  -z, --zero-copy      Force zero-copy mode.\n"
                 "  -c, --copy           Force copy mode.\n"
+                "  -f, --frame-size=n   Set the frame size (must be a power of two, default is %d).\n"
                 "\n";
-        fprintf(stderr, str, prog);
+        fprintf(stderr, str, prog, XSK_UMEM__DEFAULT_FRAME_SIZE);
         exit(EXIT_FAILURE);
 }
 
@@ -377,7 +384,7 @@ static void parse_command_line(int argc, char **argv)
         opterr = 0;
 
         for (;;) {
-                c = getopt_long(argc, argv, "Frtli:q:psSNn:cz", long_options,
+                c = getopt_long(argc, argv, "Frtli:q:psSNn:czf:", long_options,
                                 &option_index);
                 if (c == -1)
                         break;
@@ -420,6 +427,9 @@ static void parse_command_line(int argc, char **argv)
                 case 'F':
                         opt_xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
                         break;
+                case 'f':
+                        opt_xsk_frame_size = atoi(optarg);
+                        break;
                 default:
                         usage(basename(argv[0]));
                 }
@@ -432,6 +442,11 @@ static void parse_command_line(int argc, char **argv)
                 usage(basename(argv[0]));
         }
 
+        if (opt_xsk_frame_size & (opt_xsk_frame_size - 1)) {
+                fprintf(stderr, "--frame-size=%d is not a power of two\n",
+                        opt_xsk_frame_size);
+                usage(basename(argv[0]));
+        }
 }
 
 static void kick_tx(struct xsk_socket_info *xsk)
@@ -583,8 +598,7 @@ static void tx_only(struct xsk_socket_info *xsk)
 
                         for (i = 0; i < BATCH_SIZE; i++) {
                                 xsk_ring_prod__tx_desc(&xsk->tx, idx + i)->addr
-                                        = (frame_nb + i) <<
-                                        XSK_UMEM__DEFAULT_FRAME_SHIFT;
+                                        = (frame_nb + i) * opt_xsk_frame_size;
                                 xsk_ring_prod__tx_desc(&xsk->tx, idx + i)->len =
                                         sizeof(pkt_data) - 1;
                         }
@@ -661,21 +675,19 @@ int main(int argc, char **argv)
         }
 
         ret = posix_memalign(&bufs, getpagesize(), /* PAGE_SIZE aligned */
-                             NUM_FRAMES * XSK_UMEM__DEFAULT_FRAME_SIZE);
+                             NUM_FRAMES * opt_xsk_frame_size);
         if (ret)
                 exit_with_error(ret);
 
        /* Create sockets... */
-        umem = xsk_configure_umem(bufs,
-                                  NUM_FRAMES * XSK_UMEM__DEFAULT_FRAME_SIZE);
+        umem = xsk_configure_umem(bufs, NUM_FRAMES * opt_xsk_frame_size);
         xsks[num_socks++] = xsk_configure_socket(umem);
 
         if (opt_bench == BENCH_TXONLY) {
                 int i;
 
-                for (i = 0; i < NUM_FRAMES * XSK_UMEM__DEFAULT_FRAME_SIZE;
-                     i += XSK_UMEM__DEFAULT_FRAME_SIZE)
-                        (void)gen_eth_frame(umem, i);
+                for (i = 0; i < NUM_FRAMES; i++)
+                        (void)gen_eth_frame(umem, i * opt_xsk_frame_size);
         }
 
         signal(SIGINT, int_exit);