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xsk: Change the default frame size to 4096 and allow controlling it
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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 <[email protected]>
Signed-off-by: Tariq Toukan <[email protected]>
Acked-by: Saeed Mahameed <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
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@borkmann
Maxim Mikityanskiy authored and borkmann committed Jun 27, 2019
1 parent 2761ed4 commit 123e8da
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Showing 2 changed files with 29 additions and 17 deletions.
44 changes: 28 additions & 16 deletions samples/bpf/xdpsock_user.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 {
Expand Down Expand Up @@ -276,14 +277,20 @@ 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));
if (!umem)
exit_with_error(errno);

ret = xsk_umem__create(&umem->umem, buffer, size, &umem->fq, &umem->cq,
NULL);
&cfg);
if (ret)
exit_with_error(-ret);

Expand Down Expand Up @@ -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);

Expand All @@ -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}
};

Expand All @@ -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);
}

Expand All @@ -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;
Expand Down Expand Up @@ -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]));
}
Expand All @@ -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)
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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);
Expand Down
2 changes: 1 addition & 1 deletion tools/lib/bpf/xsk.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -167,7 +167,7 @@ LIBBPF_API int xsk_socket__fd(const struct xsk_socket *xsk);

#define XSK_RING_CONS__DEFAULT_NUM_DESCS 2048
#define XSK_RING_PROD__DEFAULT_NUM_DESCS 2048
#define XSK_UMEM__DEFAULT_FRAME_SHIFT 11 /* 2048 bytes */
#define XSK_UMEM__DEFAULT_FRAME_SHIFT 12 /* 4096 bytes */
#define XSK_UMEM__DEFAULT_FRAME_SIZE (1 << XSK_UMEM__DEFAULT_FRAME_SHIFT)
#define XSK_UMEM__DEFAULT_FRAME_HEADROOM 0

Expand Down

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