Subject: Re: [PATCH bpf-next 15/15] samples/bpf: sample application for AF_XDP sockets

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 24 Apr 2018 02:31:28 +0300

On Mon, Apr 23, 2018 at 03:56:19PM +0200, Björn Töpel wrote:
> From: Magnus Karlsson <[email-masked]>
> 
> This is a sample application for AF_XDP sockets. The application
> supports three different modes of operation: rxdrop, txonly and l2fwd.
> 
> To show-case a simple round-robin load-balancing between a set of
> sockets in an xskmap, set the RR_LB compile time define option to 1 in
> "xdpsock.h".
> 
> Co-authored-by: Björn Töpel <[email-masked]>
> Signed-off-by: Björn Töpel <[email-masked]>
> Signed-off-by: Magnus Karlsson <[email-masked]>
> ---
>  samples/bpf/Makefile       |   4 +
>  samples/bpf/xdpsock.h      |  11 +
>  samples/bpf/xdpsock_kern.c |  56 +++
>  samples/bpf/xdpsock_user.c | 947 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 1018 insertions(+)
>  create mode 100644 samples/bpf/xdpsock.h
>  create mode 100644 samples/bpf/xdpsock_kern.c
>  create mode 100644 samples/bpf/xdpsock_user.c
> 
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index aa8c392e2e52..d0ddc1abf20d 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -45,6 +45,7 @@ hostprogs-y += xdp_rxq_info
>  hostprogs-y += syscall_tp
>  hostprogs-y += cpustat
>  hostprogs-y += xdp_adjust_tail
> +hostprogs-y += xdpsock
>  
>  # Libbpf dependencies
>  LIBBPF := ../../tools/lib/bpf/bpf.o ../../tools/lib/bpf/nlattr.o
> @@ -97,6 +98,7 @@ xdp_rxq_info-objs := bpf_load.o $(LIBBPF) xdp_rxq_info_user.o
>  syscall_tp-objs := bpf_load.o $(LIBBPF) syscall_tp_user.o
>  cpustat-objs := bpf_load.o $(LIBBPF) cpustat_user.o
>  xdp_adjust_tail-objs := bpf_load.o $(LIBBPF) xdp_adjust_tail_user.o
> +xdpsock-objs := bpf_load.o $(LIBBPF) xdpsock_user.o
>  
>  # Tell kbuild to always build the programs
>  always := $(hostprogs-y)
> @@ -151,6 +153,7 @@ always += xdp2skb_meta_kern.o
>  always += syscall_tp_kern.o
>  always += cpustat_kern.o
>  always += xdp_adjust_tail_kern.o
> +always += xdpsock_kern.o
>  
>  HOSTCFLAGS += -I$(objtree)/usr/include
>  HOSTCFLAGS += -I$(srctree)/tools/lib/
> @@ -197,6 +200,7 @@ HOSTLOADLIBES_xdp_rxq_info += -lelf
>  HOSTLOADLIBES_syscall_tp += -lelf
>  HOSTLOADLIBES_cpustat += -lelf
>  HOSTLOADLIBES_xdp_adjust_tail += -lelf
> +HOSTLOADLIBES_xdpsock += -lelf -pthread
>  
>  # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
>  #  make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
> diff --git a/samples/bpf/xdpsock.h b/samples/bpf/xdpsock.h
> new file mode 100644
> index 000000000000..533ab81adfa1
> --- /dev/null
> +++ b/samples/bpf/xdpsock.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef XDPSOCK_H_
> +#define XDPSOCK_H_
> +
> +/* Power-of-2 number of sockets */
> +#define MAX_SOCKS 4
> +
> +/* Round-robin receive */
> +#define RR_LB 0
> +
> +#endif /* XDPSOCK_H_ */
> diff --git a/samples/bpf/xdpsock_kern.c b/samples/bpf/xdpsock_kern.c
> new file mode 100644
> index 000000000000..d8806c41362e
> --- /dev/null
> +++ b/samples/bpf/xdpsock_kern.c
> @@ -0,0 +1,56 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define KBUILD_MODNAME "foo"
> +#include <uapi/linux/bpf.h>
> +#include "bpf_helpers.h"
> +
> +#include "xdpsock.h"
> +
> +struct bpf_map_def SEC("maps") qidconf_map = {
> +	.type		= BPF_MAP_TYPE_ARRAY,
> +	.key_size	= sizeof(int),
> +	.value_size	= sizeof(int),
> +	.max_entries	= 1,
> +};
> +
> +struct bpf_map_def SEC("maps") xsks_map = {
> +	.type = BPF_MAP_TYPE_XSKMAP,
> +	.key_size = sizeof(int),
> +	.value_size = sizeof(int),
> +	.max_entries = 4,
> +};
> +
> +struct bpf_map_def SEC("maps") rr_map = {
> +	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
> +	.key_size = sizeof(int),
> +	.value_size = sizeof(unsigned int),
> +	.max_entries = 1,
> +};
> +
> +SEC("xdp_sock")
> +int xdp_sock_prog(struct xdp_md *ctx)
> +{
> +	int *qidconf, key = 0, idx;
> +	unsigned int *rr;
> +
> +	qidconf = bpf_map_lookup_elem(&qidconf_map, &key);
> +	if (!qidconf)
> +		return XDP_ABORTED;
> +
> +	if (*qidconf != ctx->rx_queue_index)
> +		return XDP_PASS;
> +
> +#if RR_LB /* NB! RR_LB is configured in xdpsock.h */
> +	rr = bpf_map_lookup_elem(&rr_map, &key);
> +	if (!rr)
> +		return XDP_ABORTED;
> +
> +	*rr = (*rr + 1) & (MAX_SOCKS - 1);
> +	idx = *rr;
> +#else
> +	idx = 0;
> +#endif
> +
> +	return bpf_redirect_map(&xsks_map, idx, 0);
> +}
> +
> +char _license[] SEC("license") = "GPL";
> diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
> new file mode 100644
> index 000000000000..690bac1a0ab7
> --- /dev/null
> +++ b/samples/bpf/xdpsock_user.c
> @@ -0,0 +1,947 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright(c) 2017 - 2018 Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +
> +#include <assert.h>
> +#include <errno.h>
> +#include <getopt.h>
> +#include <libgen.h>
> +#include <linux/bpf.h>
> +#include <linux/if_link.h>
> +#include <linux/if_xdp.h>
> +#include <linux/if_ether.h>
> +#include <net/if.h>
> +#include <signal.h>
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <net/ethernet.h>
> +#include <sys/resource.h>
> +#include <sys/socket.h>
> +#include <sys/mman.h>
> +#include <time.h>
> +#include <unistd.h>
> +#include <pthread.h>
> +#include <locale.h>
> +#include <sys/types.h>
> +#include <poll.h>
> +
> +#include "bpf_load.h"
> +#include "bpf_util.h"
> +#include "libbpf.h"
> +
> +#include "xdpsock.h"
> +
> +#ifndef SOL_XDP
> +#define SOL_XDP 283
> +#endif
> +
> +#ifndef AF_XDP
> +#define AF_XDP 44
> +#endif
> +
> +#ifndef PF_XDP
> +#define PF_XDP AF_XDP
> +#endif
> +
> +#define NUM_FRAMES 131072
> +#define FRAME_HEADROOM 0
> +#define FRAME_SIZE 2048
> +#define NUM_DESCS 1024
> +#define BATCH_SIZE 16
> +
> +#define FQ_NUM_DESCS 1024
> +#define CQ_NUM_DESCS 1024
> +
> +#define DEBUG_HEXDUMP 0
> +
> +typedef __u32 u32;
> +
> +static unsigned long prev_time;
> +
> +enum benchmark_type {
> +	BENCH_RXDROP = 0,
> +	BENCH_TXONLY = 1,
> +	BENCH_L2FWD = 2,
> +};
> +
> +static enum benchmark_type opt_bench = BENCH_RXDROP;
> +static u32 opt_xdp_flags;
> +static const char *opt_if = "";
> +static int opt_ifindex;
> +static int opt_queue;
> +static int opt_poll;
> +static int opt_shared_packet_buffer;
> +static int opt_interval = 1;
> +
> +struct xdp_umem_uqueue {
> +	u32 cached_prod;
> +	u32 cached_cons;
> +	u32 mask;
> +	u32 size;
> +	struct xdp_umem_ring *ring;
> +};
> +
> +struct xdp_umem {
> +	char (*frames)[FRAME_SIZE];
> +	struct xdp_umem_uqueue fq;
> +	struct xdp_umem_uqueue cq;
> +	int fd;
> +};
> +
> +struct xdp_uqueue {
> +	u32 cached_prod;
> +	u32 cached_cons;
> +	u32 mask;
> +	u32 size;
> +	struct xdp_rxtx_ring *ring;
> +};
> +
> +struct xdpsock {
> +	struct xdp_uqueue rx;
> +	struct xdp_uqueue tx;
> +	int sfd;
> +	struct xdp_umem *umem;
> +	u32 outstanding_tx;
> +	unsigned long rx_npkts;
> +	unsigned long tx_npkts;
> +	unsigned long prev_rx_npkts;
> +	unsigned long prev_tx_npkts;
> +};
> +
> +#define MAX_SOCKS 4
> +static int num_socks;
> +struct xdpsock *xsks[MAX_SOCKS];
> +
> +static unsigned long get_nsecs(void)
> +{
> +	struct timespec ts;
> +
> +	clock_gettime(CLOCK_MONOTONIC, &ts);
> +	return ts.tv_sec * 1000000000UL + ts.tv_nsec;
> +}
> +
> +static void dump_stats(void);
> +
> +#define lassert(expr)							\
> +	do {								\
> +		if (!(expr)) {						\
> +			fprintf(stderr, "%s:%s:%i: Assertion failed: "	\
> +				#expr ": errno: %d/\"%s\"\n",		\
> +				__FILE__, __func__, __LINE__,		\
> +				errno, strerror(errno));		\
> +			dump_stats();					\
> +			exit(EXIT_FAILURE);				\
> +		}							\
> +	} while (0)
> +
> +#define barrier() __asm__ __volatile__("": : :"memory")
> +#define u_smp_rmb() barrier()
> +#define u_smp_wmb() barrier()
> +#define likely(x) __builtin_expect(!!(x), 1)
> +#define unlikely(x) __builtin_expect(!!(x), 0)
> +
> +static const char pkt_data[] =
> +	"\x3c\xfd\xfe\x9e\x7f\x71\xec\xb1\xd7\x98\x3a\xc0\x08\x00\x45\x00"
> +	"\x00\x2e\x00\x00\x00\x00\x40\x11\x88\x97\x05\x08\x07\x08\xc8\x14"
> +	"\x1e\x04\x10\x92\x10\x92\x00\x1a\x6d\xa3\x34\x33\x1f\x69\x40\x6b"
> +	"\x54\x59\xb6\x14\x2d\x11\x44\xbf\xaf\xd9\xbe\xaa";
> +
> +static inline u32 umem_nb_free(struct xdp_umem_uqueue *q, u32 nb)
> +{
> +	u32 free_entries = q->size - (q->cached_prod - q->cached_cons);
> +
> +	if (free_entries >= nb)
> +		return free_entries;
> +
> +	/* Refresh the local tail pointer */
> +	q->cached_cons = q->ring->ptrs.consumer;
> +
> +	return q->size - (q->cached_prod - q->cached_cons);
> +}
> +
> +static inline u32 xq_nb_free(struct xdp_uqueue *q, u32 ndescs)
> +{
> +	u32 free_entries = q->cached_cons - q->cached_prod;
> +
> +	if (free_entries >= ndescs)
> +		return free_entries;
> +
> +	/* Refresh the local tail pointer */
> +	q->cached_cons = q->ring->ptrs.consumer + q->size;
> +	return q->cached_cons - q->cached_prod;
> +}
> +
> +static inline u32 umem_nb_avail(struct xdp_umem_uqueue *q, u32 nb)
> +{
> +	u32 entries = q->cached_prod - q->cached_cons;
> +
> +	if (entries == 0)
> +		q->cached_prod = q->ring->ptrs.producer;
> +
> +	entries = q->cached_prod - q->cached_cons;
> +
> +	return (entries > nb) ? nb : entries;
> +}
> +
> +static inline u32 xq_nb_avail(struct xdp_uqueue *q, u32 ndescs)
> +{
> +	u32 entries = q->cached_prod - q->cached_cons;
> +
> +	if (entries == 0)
> +		q->cached_prod = q->ring->ptrs.producer;
> +
> +	entries = q->cached_prod - q->cached_cons;
> +	return (entries > ndescs) ? ndescs : entries;
> +}
> +
> +static inline int umem_fill_to_kernel_ex(struct xdp_umem_uqueue *fq,
> +					 struct xdp_desc *d,
> +					 size_t nb)
> +{
> +	u32 i;
> +
> +	if (umem_nb_free(fq, nb) < nb)
> +		return -ENOSPC;
> +
> +	for (i = 0; i < nb; i++) {
> +		u32 idx = fq->cached_prod++ & fq->mask;
> +
> +		fq->ring->desc[idx] = d[i].idx;
> +	}
> +
> +	u_smp_wmb();
> +
> +	fq->ring->ptrs.producer = fq->cached_prod;
> +
> +	return 0;
> +}
> +
> +static inline int umem_fill_to_kernel(struct xdp_umem_uqueue *fq, u32 *d,
> +				      size_t nb)
> +{
> +	u32 i;
> +
> +	if (umem_nb_free(fq, nb) < nb)
> +		return -ENOSPC;
> +
> +	for (i = 0; i < nb; i++) {
> +		u32 idx = fq->cached_prod++ & fq->mask;
> +
> +		fq->ring->desc[idx] = d[i];
> +	}
> +
> +	u_smp_wmb();
> +
> +	fq->ring->ptrs.producer = fq->cached_prod;
> +
> +	return 0;
> +}
> +
> +static inline size_t umem_complete_from_kernel(struct xdp_umem_uqueue *cq,
> +					       u32 *d, size_t nb)
> +{
> +	u32 idx, i, entries = umem_nb_avail(cq, nb);
> +
> +	u_smp_rmb();
> +
> +	for (i = 0; i < entries; i++) {
> +		idx = cq->cached_cons++ & cq->mask;
> +		d[i] = cq->ring->desc[idx];
> +	}
> +
> +	if (entries > 0) {
> +		u_smp_wmb();
> +
> +		cq->ring->ptrs.consumer = cq->cached_cons;
> +	}
> +
> +	return entries;
> +}
> +
> +static inline void *xq_get_data(struct xdpsock *xsk, __u32 idx, __u32 off)
> +{
> +	lassert(idx < NUM_FRAMES);
> +	return &xsk->umem->frames[idx][off];
> +}
> +
> +static inline int xq_enq(struct xdp_uqueue *uq,
> +			 const struct xdp_desc *descs,
> +			 unsigned int ndescs)
> +{
> +	struct xdp_rxtx_ring *r = uq->ring;
> +	unsigned int i;
> +
> +	if (xq_nb_free(uq, ndescs) < ndescs)
> +		return -ENOSPC;
> +
> +	for (i = 0; i < ndescs; i++) {
> +		u32 idx = uq->cached_prod++ & uq->mask;
> +
> +		r->desc[idx].idx = descs[i].idx;
> +		r->desc[idx].len = descs[i].len;
> +		r->desc[idx].offset = descs[i].offset;
> +	}
> +
> +	u_smp_wmb();
> +
> +	r->ptrs.producer = uq->cached_prod;
> +	return 0;
> +}
> +
> +static inline int xq_enq_tx_only(struct xdp_uqueue *uq,
> +				 __u32 idx, unsigned int ndescs)
> +{
> +	struct xdp_rxtx_ring *q = uq->ring;
> +	unsigned int i;
> +
> +	if (xq_nb_free(uq, ndescs) < ndescs)
> +		return -ENOSPC;
> +
> +	for (i = 0; i < ndescs; i++) {
> +		u32 idx = uq->cached_prod++ & uq->mask;
> +
> +		q->desc[idx].idx	= idx + i;
> +		q->desc[idx].len	= sizeof(pkt_data) - 1;
> +		q->desc[idx].offset	= 0;
> +	}
> +
> +	u_smp_wmb();
> +
> +	q->ptrs.producer = uq->cached_prod;
> +	return 0;
> +}
> +
> +static inline int xq_deq(struct xdp_uqueue *uq,
> +			 struct xdp_desc *descs,
> +			 int ndescs)
> +{
> +	struct xdp_rxtx_ring *r = uq->ring;
> +	unsigned int idx;
> +	int i, entries;
> +
> +	entries = xq_nb_avail(uq, ndescs);
> +
> +	u_smp_rmb();
> +
> +	for (i = 0; i < entries; i++) {
> +		idx = uq->cached_cons++ & uq->mask;
> +		descs[i] = r->desc[idx];
> +	}
> +
> +	if (entries > 0) {
> +		u_smp_wmb();
> +
> +		r->ptrs.consumer = uq->cached_cons;
> +	}
> +
> +	return entries;
> +}

Interesting, I was under the impression that you were
planning to get rid of consumer/producer counters
and validate the descriptors instead.

That's the ptr_ring design.

You can then drop all the code around synchronising
counter caches, as well as smp_rmb barriers.

> +
> +static void swap_mac_addresses(void *data)
> +{
> +	struct ether_header *eth = (struct ether_header *)data;
> +	struct ether_addr *src_addr = (struct ether_addr *)&eth->ether_shost;
> +	struct ether_addr *dst_addr = (struct ether_addr *)&eth->ether_dhost;
> +	struct ether_addr tmp;
> +
> +	tmp = *src_addr;
> +	*src_addr = *dst_addr;
> +	*dst_addr = tmp;
> +}
> +
> +#if DEBUG_HEXDUMP
> +static void hex_dump(void *pkt, size_t length, const char *prefix)
> +{
> +	int i = 0;
> +	const unsigned char *address = (unsigned char *)pkt;
> +	const unsigned char *line = address;
> +	size_t line_size = 32;
> +	unsigned char c;
> +
> +	printf("length = %zu\n", length);
> +	printf("%s | ", prefix);
> +	while (length-- > 0) {
> +		printf("%02X ", *address++);
> +		if (!(++i % line_size) || (length == 0 && i % line_size)) {
> +			if (length == 0) {
> +				while (i++ % line_size)
> +					printf("__ ");
> +			}
> +			printf(" | ");	/* right close */
> +			while (line < address) {
> +				c = *line++;
> +				printf("%c", (c < 33 || c == 255) ? 0x2E : c);
> +			}
> +			printf("\n");
> +			if (length > 0)
> +				printf("%s | ", prefix);
> +		}
> +	}
> +	printf("\n");
> +}
> +#endif
> +
> +static size_t gen_eth_frame(char *frame)
> +{
> +	memcpy(frame, pkt_data, sizeof(pkt_data) - 1);
> +	return sizeof(pkt_data) - 1;
> +}
> +
> +static struct xdp_umem *xdp_umem_configure(int sfd)
> +{
> +	int fq_size = FQ_NUM_DESCS, cq_size = CQ_NUM_DESCS;
> +	struct xdp_umem_reg mr;
> +	struct xdp_umem *umem;
> +	void *bufs;
> +
> +	umem = calloc(1, sizeof(*umem));
> +	lassert(umem);
> +
> +	lassert(posix_memalign(&bufs, getpagesize(), /* PAGE_SIZE aligned */
> +			       NUM_FRAMES * FRAME_SIZE) == 0);
> +
> +	mr.addr = (__u64)bufs;
> +	mr.len = NUM_FRAMES * FRAME_SIZE;
> +	mr.frame_size = FRAME_SIZE;
> +	mr.frame_headroom = FRAME_HEADROOM;
> +
> +	lassert(setsockopt(sfd, SOL_XDP, XDP_UMEM_REG, &mr, sizeof(mr)) == 0);
> +	lassert(setsockopt(sfd, SOL_XDP, XDP_UMEM_FILL_RING, &fq_size,
> +			   sizeof(int)) == 0);
> +	lassert(setsockopt(sfd, SOL_XDP, XDP_UMEM_COMPLETION_RING, &cq_size,
> +			   sizeof(int)) == 0);
> +
> +	umem->fq.ring = mmap(0, sizeof(struct xdp_umem_ring) +
> +			     FQ_NUM_DESCS * sizeof(u32),
> +			     PROT_READ | PROT_WRITE,
> +			     MAP_SHARED | MAP_POPULATE, sfd,
> +			     XDP_UMEM_PGOFF_FILL_RING);
> +	lassert(umem->fq.ring != MAP_FAILED);
> +
> +	umem->fq.mask = FQ_NUM_DESCS - 1;
> +	umem->fq.size = FQ_NUM_DESCS;
> +
> +	umem->cq.ring = mmap(0, sizeof(struct xdp_umem_ring) +
> +			     CQ_NUM_DESCS * sizeof(u32),
> +			     PROT_READ | PROT_WRITE,
> +			     MAP_SHARED | MAP_POPULATE, sfd,
> +			     XDP_UMEM_PGOFF_COMPLETION_RING);
> +	lassert(umem->cq.ring != MAP_FAILED);
> +
> +	umem->cq.mask = CQ_NUM_DESCS - 1;
> +	umem->cq.size = CQ_NUM_DESCS;
> +
> +	umem->frames = (char (*)[FRAME_SIZE])bufs;
> +	umem->fd = sfd;
> +
> +	if (opt_bench == BENCH_TXONLY) {
> +		int i;
> +
> +		for (i = 0; i < NUM_FRAMES; i++)
> +			(void)gen_eth_frame(&umem->frames[i][0]);
> +	}
> +
> +	return umem;
> +}
> +
> +static struct xdpsock *xsk_configure(struct xdp_umem *umem)
> +{
> +	struct sockaddr_xdp sxdp = {};
> +	int sfd, ndescs = NUM_DESCS;
> +	struct xdpsock *xsk;
> +	bool shared = true;
> +	u32 i;
> +
> +	sfd = socket(PF_XDP, SOCK_RAW, 0);
> +	lassert(sfd >= 0);
> +
> +	xsk = calloc(1, sizeof(*xsk));
> +	lassert(xsk);
> +
> +	xsk->sfd = sfd;
> +	xsk->outstanding_tx = 0;
> +
> +	if (!umem) {
> +		shared = false;
> +		xsk->umem = xdp_umem_configure(sfd);
> +	} else {
> +		xsk->umem = umem;
> +	}
> +
> +	lassert(setsockopt(sfd, SOL_XDP, XDP_RX_RING,
> +			   &ndescs, sizeof(int)) == 0);
> +	lassert(setsockopt(sfd, SOL_XDP, XDP_TX_RING,
> +			   &ndescs, sizeof(int)) == 0);
> +
> +	/* Rx */
> +	xsk->rx.ring = mmap(NULL,
> +			    sizeof(struct xdp_ring) +
> +			    NUM_DESCS * sizeof(struct xdp_desc),
> +			    PROT_READ | PROT_WRITE,
> +			    MAP_SHARED | MAP_POPULATE, sfd,
> +			    XDP_PGOFF_RX_RING);
> +	lassert(xsk->rx.ring != MAP_FAILED);
> +
> +	if (!shared) {
> +		for (i = 0; i < NUM_DESCS / 2; i++)
> +			lassert(umem_fill_to_kernel(&xsk->umem->fq, &i, 1)
> +				== 0);
> +	}
> +
> +	/* Tx */
> +	xsk->tx.ring = mmap(NULL,
> +			 sizeof(struct xdp_ring) +
> +			 NUM_DESCS * sizeof(struct xdp_desc),
> +			 PROT_READ | PROT_WRITE,
> +			 MAP_SHARED | MAP_POPULATE, sfd,
> +			 XDP_PGOFF_TX_RING);
> +	lassert(xsk->tx.ring != MAP_FAILED);
> +
> +	xsk->rx.mask = NUM_DESCS - 1;
> +	xsk->rx.size = NUM_DESCS;
> +
> +	xsk->tx.mask = NUM_DESCS - 1;
> +	xsk->tx.size = NUM_DESCS;
> +
> +	sxdp.sxdp_family = PF_XDP;
> +	sxdp.sxdp_ifindex = opt_ifindex;
> +	sxdp.sxdp_queue_id = opt_queue;
> +	if (shared) {
> +		sxdp.sxdp_flags = XDP_SHARED_UMEM;
> +		sxdp.sxdp_shared_umem_fd = umem->fd;
> +	}
> +
> +	lassert(bind(sfd, (struct sockaddr *)&sxdp, sizeof(sxdp)) == 0);
> +
> +	return xsk;
> +}
> +
> +static void print_benchmark(bool running)
> +{
> +	const char *bench_str = "INVALID";
> +
> +	if (opt_bench == BENCH_RXDROP)
> +		bench_str = "rxdrop";
> +	else if (opt_bench == BENCH_TXONLY)
> +		bench_str = "txonly";
> +	else if (opt_bench == BENCH_L2FWD)
> +		bench_str = "l2fwd";
> +
> +	printf("%s:%d %s ", opt_if, opt_queue, bench_str);
> +	if (opt_xdp_flags & XDP_FLAGS_SKB_MODE)
> +		printf("xdp-skb ");
> +	else if (opt_xdp_flags & XDP_FLAGS_DRV_MODE)
> +		printf("xdp-drv ");
> +	else
> +		printf("	");
> +
> +	if (opt_poll)
> +		printf("poll() ");
> +
> +	if (running) {
> +		printf("running...");
> +		fflush(stdout);
> +	}
> +}
> +
> +static void dump_stats(void)
> +{
> +	unsigned long now = get_nsecs();
> +	long dt = now - prev_time;
> +	int i;
> +
> +	prev_time = now;
> +
> +	for (i = 0; i < num_socks; i++) {
> +		char *fmt = "%-15s %'-11.0f %'-11lu\n";
> +		double rx_pps, tx_pps;
> +
> +		rx_pps = (xsks[i]->rx_npkts - xsks[i]->prev_rx_npkts) *
> +			 1000000000. / dt;
> +		tx_pps = (xsks[i]->tx_npkts - xsks[i]->prev_tx_npkts) *
> +			 1000000000. / dt;
> +
> +		printf("\n sock%d@", i);
> +		print_benchmark(false);
> +		printf("\n");
> +
> +		printf("%-15s %-11s %-11s %-11.2f\n", "", "pps", "pkts",
> +		       dt / 1000000000.);
> +		printf(fmt, "rx", rx_pps, xsks[i]->rx_npkts);
> +		printf(fmt, "tx", tx_pps, xsks[i]->tx_npkts);
> +
> +		xsks[i]->prev_rx_npkts = xsks[i]->rx_npkts;
> +		xsks[i]->prev_tx_npkts = xsks[i]->tx_npkts;
> +	}
> +}
> +
> +static void *poller(void *arg)
> +{
> +	(void)arg;
> +	for (;;) {
> +		sleep(opt_interval);
> +		dump_stats();
> +	}
> +
> +	return NULL;
> +}
> +
> +static void int_exit(int sig)
> +{
> +	(void)sig;
> +	dump_stats();
> +	bpf_set_link_xdp_fd(opt_ifindex, -1, opt_xdp_flags);
> +	exit(EXIT_SUCCESS);
> +}
> +
> +static struct option long_options[] = {
> +	{"rxdrop", no_argument, 0, 'r'},
> +	{"txonly", no_argument, 0, 't'},
> +	{"l2fwd", no_argument, 0, 'l'},
> +	{"interface", required_argument, 0, 'i'},
> +	{"queue", required_argument, 0, 'q'},
> +	{"poll", no_argument, 0, 'p'},
> +	{"shared-buffer", no_argument, 0, 's'},
> +	{"xdp-skb", no_argument, 0, 'S'},
> +	{"xdp-native", no_argument, 0, 'N'},
> +	{"interval", required_argument, 0, 'n'},
> +	{0, 0, 0, 0}
> +};
> +
> +static void usage(const char *prog)
> +{
> +	const char *str =
> +		"  Usage: %s [OPTIONS]\n"
> +		"  Options:\n"
> +		"  -r, --rxdrop		Discard all incoming packets (default)\n"
> +		"  -t, --txonly		Only send packets\n"
> +		"  -l, --l2fwd		MAC swap L2 forwarding\n"
> +		"  -i, --interface=n	Run on interface n\n"
> +		"  -q, --queue=n	Use queue n (default 0)\n"
> +		"  -p, --poll		Use poll syscall\n"
> +		"  -s, --shared-buffer	Use shared packet buffer\n"
> +		"  -S, --xdp-skb=n	Use XDP skb-mod\n"
> +		"  -N, --xdp-native=n	Enfore XDP native mode\n"
> +		"  -n, --interval=n	Specify statistics update interval (default 1 sec).\n"
> +		"\n";
> +	fprintf(stderr, str, prog);
> +	exit(EXIT_FAILURE);
> +}
> +
> +static void parse_command_line(int argc, char **argv)
> +{
> +	int option_index, c;
> +
> +	opterr = 0;
> +
> +	for (;;) {
> +		c = getopt_long(argc, argv, "rtli:q:psSNn:", long_options,
> +				&option_index);
> +		if (c == -1)
> +			break;
> +
> +		switch (c) {
> +		case 'r':
> +			opt_bench = BENCH_RXDROP;
> +			break;
> +		case 't':
> +			opt_bench = BENCH_TXONLY;
> +			break;
> +		case 'l':
> +			opt_bench = BENCH_L2FWD;
> +			break;
> +		case 'i':
> +			opt_if = optarg;
> +			break;
> +		case 'q':
> +			opt_queue = atoi(optarg);
> +			break;
> +		case 's':
> +			opt_shared_packet_buffer = 1;
> +			break;
> +		case 'p':
> +			opt_poll = 1;
> +			break;
> +		case 'S':
> +			opt_xdp_flags |= XDP_FLAGS_SKB_MODE;
> +			break;
> +		case 'N':
> +			opt_xdp_flags |= XDP_FLAGS_DRV_MODE;
> +			break;
> +		case 'n':
> +			opt_interval = atoi(optarg);
> +			break;
> +		default:
> +			usage(basename(argv[0]));
> +		}
> +	}
> +
> +	opt_ifindex = if_nametoindex(opt_if);
> +	if (!opt_ifindex) {
> +		fprintf(stderr, "ERROR: interface \"%s\" does not exist\n",
> +			opt_if);
> +		usage(basename(argv[0]));
> +	}
> +}
> +
> +static void kick_tx(int fd)
> +{
> +	int ret;
> +
> +	ret = sendto(fd, NULL, 0, MSG_DONTWAIT, NULL, 0);
> +	if (ret >= 0 || errno == ENOBUFS || errno == EAGAIN)
> +		return;
> +	lassert(0);
> +}
> +
> +static inline void complete_tx_l2fwd(struct xdpsock *xsk)
> +{
> +	u32 descs[BATCH_SIZE];
> +	unsigned int rcvd;
> +	size_t ndescs;
> +
> +	if (!xsk->outstanding_tx)
> +		return;
> +
> +	kick_tx(xsk->sfd);
> +	ndescs = (xsk->outstanding_tx > BATCH_SIZE) ? BATCH_SIZE :
> +		 xsk->outstanding_tx;
> +
> +	/* re-add completed Tx buffers */
> +	rcvd = umem_complete_from_kernel(&xsk->umem->cq, descs, ndescs);
> +	if (rcvd > 0) {
> +		umem_fill_to_kernel(&xsk->umem->fq, descs, rcvd);
> +		xsk->outstanding_tx -= rcvd;
> +		xsk->tx_npkts += rcvd;
> +	}
> +}
> +
> +static inline void complete_tx_only(struct xdpsock *xsk)
> +{
> +	u32 descs[BATCH_SIZE];
> +	unsigned int rcvd;
> +
> +	if (!xsk->outstanding_tx)
> +		return;
> +
> +	kick_tx(xsk->sfd);
> +
> +	rcvd = umem_complete_from_kernel(&xsk->umem->cq, descs, BATCH_SIZE);
> +	if (rcvd > 0) {
> +		xsk->outstanding_tx -= rcvd;
> +		xsk->tx_npkts += rcvd;
> +	}
> +}
> +
> +static void rx_drop(struct xdpsock *xsk)
> +{
> +	struct xdp_desc descs[BATCH_SIZE];
> +	unsigned int rcvd, i;
> +
> +	rcvd = xq_deq(&xsk->rx, descs, BATCH_SIZE);
> +	if (!rcvd)
> +		return;
> +
> +	for (i = 0; i < rcvd; i++) {
> +		u32 idx = descs[i].idx;
> +
> +		lassert(idx < NUM_FRAMES);
> +#if DEBUG_HEXDUMP
> +		char *pkt;
> +		char buf[32];
> +
> +		pkt = xq_get_data(xsk, idx, descs[i].offset);
> +		sprintf(buf, "idx=%d", idx);
> +		hex_dump(pkt, descs[i].len, buf);
> +#endif
> +	}
> +
> +	xsk->rx_npkts += rcvd;
> +
> +	umem_fill_to_kernel_ex(&xsk->umem->fq, descs, rcvd);
> +}
> +
> +static void rx_drop_all(void)
> +{
> +	struct pollfd fds[MAX_SOCKS + 1];
> +	int i, ret, timeout, nfds = 1;
> +
> +	memset(fds, 0, sizeof(fds));
> +
> +	for (i = 0; i < num_socks; i++) {
> +		fds[i].fd = xsks[i]->sfd;
> +		fds[i].events = POLLIN;
> +		timeout = 1000; /* 1sn */
> +	}
> +
> +	for (;;) {
> +		if (opt_poll) {
> +			ret = poll(fds, nfds, timeout);
> +			if (ret <= 0)
> +				continue;
> +		}
> +
> +		for (i = 0; i < num_socks; i++)
> +			rx_drop(xsks[i]);
> +	}
> +}
> +
> +static void tx_only(struct xdpsock *xsk)
> +{
> +	int timeout, ret, nfds = 1;
> +	struct pollfd fds[nfds + 1];
> +	unsigned int idx = 0;
> +
> +	memset(fds, 0, sizeof(fds));
> +	fds[0].fd = xsk->sfd;
> +	fds[0].events = POLLOUT;
> +	timeout = 1000; /* 1sn */
> +
> +	for (;;) {
> +		if (opt_poll) {
> +			ret = poll(fds, nfds, timeout);
> +			if (ret <= 0)
> +				continue;
> +
> +			if (fds[0].fd != xsk->sfd ||
> +			    !(fds[0].revents & POLLOUT))
> +				continue;
> +		}
> +
> +		if (xq_nb_free(&xsk->tx, BATCH_SIZE) >= BATCH_SIZE) {
> +			lassert(xq_enq_tx_only(&xsk->tx, idx, BATCH_SIZE) == 0);
> +
> +			xsk->outstanding_tx += BATCH_SIZE;
> +			idx += BATCH_SIZE;
> +			idx %= NUM_FRAMES;
> +		}
> +
> +		complete_tx_only(xsk);
> +	}
> +}
> +
> +static void l2fwd(struct xdpsock *xsk)
> +{
> +	for (;;) {
> +		struct xdp_desc descs[BATCH_SIZE];
> +		unsigned int rcvd, i;
> +		int ret;
> +
> +		for (;;) {
> +			complete_tx_l2fwd(xsk);
> +
> +			rcvd = xq_deq(&xsk->rx, descs, BATCH_SIZE);
> +			if (rcvd > 0)
> +				break;
> +		}
> +
> +		for (i = 0; i < rcvd; i++) {
> +			char *pkt = xq_get_data(xsk, descs[i].idx,
> +						descs[i].offset);
> +
> +			swap_mac_addresses(pkt);
> +#if DEBUG_HEXDUMP
> +			char buf[32];
> +			u32 idx = descs[i].idx;
> +
> +			sprintf(buf, "idx=%d", idx);
> +			hex_dump(pkt, descs[i].len, buf);
> +#endif
> +		}
> +
> +		xsk->rx_npkts += rcvd;
> +
> +		ret = xq_enq(&xsk->tx, descs, rcvd);
> +		lassert(ret == 0);
> +		xsk->outstanding_tx += rcvd;
> +	}
> +}
> +
> +int main(int argc, char **argv)
> +{
> +	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
> +	char xdp_filename[256];
> +	int i, ret, key = 0;
> +	pthread_t pt;
> +
> +	parse_command_line(argc, argv);
> +
> +	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
> +		fprintf(stderr, "ERROR: setrlimit(RLIMIT_MEMLOCK) \"%s\"\n",
> +			strerror(errno));
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	snprintf(xdp_filename, sizeof(xdp_filename), "%s_kern.o", argv[0]);
> +
> +	if (load_bpf_file(xdp_filename)) {
> +		fprintf(stderr, "ERROR: load_bpf_file %s\n", bpf_log_buf);
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	if (!prog_fd[0]) {
> +		fprintf(stderr, "ERROR: load_bpf_file: \"%s\"\n",
> +			strerror(errno));
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	if (bpf_set_link_xdp_fd(opt_ifindex, prog_fd[0], opt_xdp_flags) < 0) {
> +		fprintf(stderr, "ERROR: link set xdp fd failed\n");
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	ret = bpf_map_update_elem(map_fd[0], &key, &opt_queue, 0);
> +	if (ret) {
> +		fprintf(stderr, "ERROR: bpf_map_update_elem qidconf\n");
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	/* Create sockets... */
> +	xsks[num_socks++] = xsk_configure(NULL);
> +
> +#if RR_LB
> +	for (i = 0; i < MAX_SOCKS - 1; i++)
> +		xsks[num_socks++] = xsk_configure(xsks[0]->umem);
> +#endif
> +
> +	/* ...and insert them into the map. */
> +	for (i = 0; i < num_socks; i++) {
> +		key = i;
> +		ret = bpf_map_update_elem(map_fd[1], &key, &xsks[i]->sfd, 0);
> +		if (ret) {
> +			fprintf(stderr, "ERROR: bpf_map_update_elem %d\n", i);
> +			exit(EXIT_FAILURE);
> +		}
> +	}
> +
> +	signal(SIGINT, int_exit);
> +	signal(SIGTERM, int_exit);
> +	signal(SIGABRT, int_exit);
> +
> +	setlocale(LC_ALL, "");
> +
> +	ret = pthread_create(&pt, NULL, poller, NULL);
> +	lassert(ret == 0);
> +
> +	prev_time = get_nsecs();
> +
> +	if (opt_bench == BENCH_RXDROP)
> +		rx_drop_all();
> +	else if (opt_bench == BENCH_TXONLY)
> +		tx_only(xsks[0]);
> +	else
> +		l2fwd(xsks[0]);
> +
> +	return 0;
> +}
> -- 
> 2.14.1