Re: [PATCH v6 2/2] Add l2reflect measurement application

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi Felix,

First, I support the idea of having the l2reflect application part of
the DPDK repository.

Please note CI failed to build it on different platforms:
http://mails.dpdk.org/archives/test-report/2022-September/304617.html

It also fails to build on my Fc35 machine:
[3237/3537] Compiling C object app/dpdk-l2reflect.p/l2reflect_main.c.o
../app/l2reflect/main.c: In function ‘l2reflect_main_loop’:
../app/l2reflect/main.c:560:19: warning: array subscript ‘uint64_t {aka 
long unsigned int}[0]’ is partly outside array bounds of ‘struct 
rte_ether_addr[1]’ [-Warray-bounds]
   560 |         i_win = ((*((uint64_t *)&l2reflect_port_eth_addr)   & 
MAC_ADDR_CMP) >
       |                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../app/l2reflect/main.c:110:23: note: while referencing 
‘l2reflect_port_eth_addr’
   110 | struct rte_ether_addr l2reflect_port_eth_addr;
       |                       ^~~~~~~~~~~~~~~~~~~~~~~
../app/l2reflect/main.c:561:27: warning: array subscript ‘uint64_t {aka 
long unsigned int}[0]’ is partly outside array bounds of ‘struct 
rte_ether_addr[1]’ [-Warray-bounds]
   561 |                          (*((uint64_t 
*)&l2reflect_remote_eth_addr) & MAC_ADDR_CMP));
       |                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../app/l2reflect/main.c:111:23: note: while referencing 
‘l2reflect_remote_eth_addr’
   111 | struct rte_ether_addr l2reflect_remote_eth_addr;
       |                       ^~~~~~~~~~~~~~~~~

Some more comments inline:

On 9/2/22 10:45, Felix Moessbauer wrote:
> The l2reflect application implements a ping-pong benchmark to
> measure the latency between two instances. For communication,
> we use raw ethernet and send one packet at a time. The timing data
> is collected locally and min/max/avg values are displayed in a TUI.
> Finally, a histogram of the latencies is printed which can be
> further processed with the jitterdebugger visualization scripts.
> To debug latency spikes, a max threshold can be defined.
> If it is hit, a trace point is created on both instances.
> 
> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> Signed-off-by: Henning Schild <henning.schild@siemens.com>
> ---
>   app/l2reflect/colors.c    |   34 ++
>   app/l2reflect/colors.h    |   19 +
>   app/l2reflect/l2reflect.h |   53 ++
>   app/l2reflect/main.c      | 1007 +++++++++++++++++++++++++++++++++++++
>   app/l2reflect/meson.build |   21 +
>   app/l2reflect/payload.h   |   26 +
>   app/l2reflect/stats.c     |  225 +++++++++
>   app/l2reflect/stats.h     |   67 +++
>   app/l2reflect/utils.c     |   67 +++
>   app/l2reflect/utils.h     |   20 +
>   app/meson.build           |    1 +
>   11 files changed, 1540 insertions(+)
>   create mode 100644 app/l2reflect/colors.c
>   create mode 100644 app/l2reflect/colors.h
>   create mode 100644 app/l2reflect/l2reflect.h
>   create mode 100644 app/l2reflect/main.c
>   create mode 100644 app/l2reflect/meson.build
>   create mode 100644 app/l2reflect/payload.h
>   create mode 100644 app/l2reflect/stats.c
>   create mode 100644 app/l2reflect/stats.h
>   create mode 100644 app/l2reflect/utils.c
>   create mode 100644 app/l2reflect/utils.h

If we agree to have this application in app/ directory,
I think you'll have to add documentation for this new tool in
doc/guides/tools/.

> diff --git a/app/l2reflect/colors.c b/app/l2reflect/colors.c
> new file mode 100644
> index 0000000000..af881d8788
> --- /dev/null
> +++ b/app/l2reflect/colors.c
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + */
> +
> +#include "colors.h"
> +
> +const struct color_palette *colors;
> +
> +static const struct color_palette color_palette_default = {
> +	.red = "\x1b[01;31m",
> +	.green = "\x1b[01;32m",
> +	.yellow = "\x1b[01;33m",
> +	.blue = "\x1b[01;34m",
> +	.magenta = "\x1b[01;35m",
> +	.cyan = "\x1b[01;36m",
> +	.reset = "\x1b[0m"
> +};
> +
> +static const struct color_palette color_palette_bw = { .red = "",
> +						       .green = "",
> +						       .yellow = "",
> +						       .blue = "",
> +						       .magenta = "",
> +						       .cyan = "",
> +						       .reset = "" };
> +
> +void
> +enable_colors(int enable)
> +{
> +	if (enable)
> +		colors = &color_palette_default;
> +	else
> +		colors = &color_palette_bw;
> +}
> diff --git a/app/l2reflect/colors.h b/app/l2reflect/colors.h
> new file mode 100644
> index 0000000000..346547138b
> --- /dev/null
> +++ b/app/l2reflect/colors.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + */
> +#ifndef _L2REFLECT_COLORS_H_
> +#define _L2REFLECT_COLORS_H_
> +
> +/* posix terminal colors */
> +struct color_palette {
> +	const char *red, *green, *yellow, *blue, *magenta, *cyan, *reset;
> +};
> +
> +/* ptr to the current tui color palette */
> +extern const struct color_palette *colors;
> +
> +/* disable colored output */
> +void
> +enable_colors(int enable);
> +
> +#endif /* _L2REFLECT_COLORS_H_ */
> diff --git a/app/l2reflect/l2reflect.h b/app/l2reflect/l2reflect.h
> new file mode 100644
> index 0000000000..922bd7c281
> --- /dev/null
> +++ b/app/l2reflect/l2reflect.h
> @@ -0,0 +1,53 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + */
> +
> +#include <stdatomic.h>
> +
> +#ifndef _L2REFLECT_L2REFLECT_H_
> +#define _L2REFLECT_L2REFLECT_H_
> +
> +#define RTE_LOGTYPE_L2REFLECT RTE_LOGTYPE_USER1
> +
> +/* max size that common 1G NICs support */
> +#define MAX_JUMBO_PKT_LEN 9600
> +
> +/* Used to compare MAC addresses. */
> +#define MAC_ADDR_CMP 0xFFFFFFFFFFFFull
> +
> +#define MAX(x, y) (((x) > (y)) ? (x) : (y))
> +#define MIN(x, y) (((x) < (y)) ? (x) : (y))
> +
> +enum {
> +	TRACE_TYPE_DATA,
> +	TRACE_TYPE_HELO,
> +	TRACE_TYPE_EHLO,
> +	TRACE_TYPE_RSET,
> +	TRACE_TYPE_QUIT,
> +};
> +
> +enum STATE {
> +	/* elect the initial sender */
> +	S_ELECT_LEADER = 1,
> +	/* reset the counters */
> +	S_RESET_TRX = 2,
> +	/* measurement S_RUNNING */
> +	S_RUNNING = 4,
> +	/* terminated by local event */
> +	S_LOCAL_TERM = 8,
> +	/* terminated by remote event */
> +	S_REMOTE_TERM = 16
> +};
> +
> +extern int l2reflect_hist;
> +extern unsigned int l2reflect_hist_buckets;
> +extern atomic_int l2reflect_output_hist;
> +extern int l2reflect_interrupt;
> +extern uint64_t l2reflect_sleep_msec;
> +extern uint64_t l2reflect_pkt_bytes;
> +extern uint16_t l2reflect_port_number;
> +extern atomic_int l2reflect_state;
> +extern struct rte_ether_addr l2reflect_port_eth_addr;
> +extern struct rte_ether_addr l2reflect_remote_eth_addr;
> +
> +#endif /* _L2REFLECT_L2REFLECT_H_ */
> diff --git a/app/l2reflect/main.c b/app/l2reflect/main.c
> new file mode 100644
> index 0000000000..33a87e8fad
> --- /dev/null
> +++ b/app/l2reflect/main.c
> @@ -0,0 +1,1007 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + *
> + * The l2reflect application implements a ping-pong benchmark to
> + * measure the latency between two instances. For communication,
> + * we use raw ethernet and send one packet at a time. The timing data
> + * is collected locally and min/max/avg values are displayed in a TUI.
> + * Finally, a histogram of the latencies is printed which can be
> + * further processed with the jitterdebugger visualization scripts.
> + * To debug latency spikes, a max threshold can be defined.
> + * If it is hit, a trace point is created on both instances.
> + *
> + * Examples:
> + *   launch (non-rt kernel): l2reflect --lcores 0@0,1@6 -n 1
> + *   launch (rt kernel): l2reflect --lcores 0@0,1@6 -n 1 -- -P 50 -r -l
> + *
> + * For histogram data, launch with -H <usec> -F <output file>, e.g.
> + * -H 10 -F histogram.json for a histogram with 10 usec buckets which
> + * is written to a histogram.json file. This file can then be visualized
> + * using the jitterdebugger plotting scripts:
> + *   jitterplot hist histogram.json
> + *
> + * While the application is running, it can be controlled by sending
> + * signals to one of the processes:
> + * - SIGUSR1: reset the min/max/avg on both instances
> + * - SIGUSR2: output / write the current histogram
> + * - SIGHUP/SIGINT: gracefully terminate both instances
> + *
> + * Note on wiring:
> + * The l2reflect application sends the packets via a physical ethernet
> + * interface. When running both instances on a single system, at least
> + * two dedicated physical ports and a (physical) loopback between them
> + * is required.

Above text could be used as a basis for the documentation.

> + */
> +
> +#include <stdio.h>
> +#include <errno.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <stdint.h>
> +#include <time.h>
> +#include <inttypes.h>
> +#include <getopt.h>
> +#include <sys/signal.h>
> +#include <assert.h>
> +#include <unistd.h>
> +#ifdef HAS_SYS_IO
> +#include <sys/io.h>
> +#endif
> +#include <sched.h>
> +#include <sys/mman.h>
> +#include <stdatomic.h>
> +
> +#include <rte_common.h>
> +#include <rte_errno.h>
> +#include <rte_log.h>
> +#include <rte_memory.h>
> +#include <rte_memcpy.h>
> +#include <rte_memzone.h>
> +#include <rte_eal.h>
> +#include <rte_eal_trace.h>
> +#include <rte_per_lcore.h>
> +#include <rte_launch.h>
> +#include <rte_atomic.h>
> +#include <rte_cycles.h>
> +#include <rte_prefetch.h>
> +#include <rte_lcore.h>
> +#include <rte_per_lcore.h>
> +#include <rte_branch_prediction.h>
> +#include <rte_interrupts.h>
> +#include <rte_random.h>
> +#include <rte_debug.h>
> +#include <rte_ether.h>
> +#include <rte_ethdev.h>
> +#include <rte_ring.h>
> +#include <rte_mempool.h>
> +#include <rte_mbuf.h>
> +
> +#include "l2reflect.h"
> +#include "payload.h"
> +#include "utils.h"
> +#include "colors.h"
> +#include "stats.h"
> +
> +#define NSEC_PER_SEC 1000000000
> +
> +#define NB_MBUF 2047
> +
> +#define MAX_PKT_BURST 32
> +/* warmup a few round before starting the measurement */
> +#define WARMUP_ROUNDS 42

Would it make sense to have this as default value and provide the user
with the possibility to configure it via command line?

> +
> +/* break after one second */
> +#define DEFAULT_BREAKVAL_USEC 1000000ull
> +/* break if no rx for more than this rounds */
> +#define RX_TIMEOUT_MASK ~0xFFFFFull
> +
> +/* delay between two election packets */
> +#define DELAY_ELECTION_MS 500
> +
> +int l2reflect_hist;
> +unsigned int l2reflect_hist_buckets = HIST_NUM_BUCKETS_DEFAULT;
> +atomic_int l2reflect_output_hist;
> +int l2reflect_fake_mac;
> +int l2reflect_interrupt;
> +uint64_t l2reflect_sleep_msec;
> +uint64_t l2reflect_pkt_bytes = 64;
> +uint16_t l2reflect_port_number;
> +atomic_int l2reflect_state;
> +struct rte_ether_addr l2reflect_port_eth_addr;
> +struct rte_ether_addr l2reflect_remote_eth_addr;
> +
> +static struct timespec last_sent, last_recv;
> +static int quiet, disable_int, priority, policy, l2reflect_mlock;
> +
> +static atomic_int sleep_start;
> +static uint64_t rounds;
> +
> +/* Configurable number of RX/TX ring descriptors */
> +#define RTE_TEST_RX_DESC_DEFAULT 128
> +#define RTE_TEST_TX_DESC_DEFAULT 128
> +static uint16_t nb_rxd = RTE_TEST_RX_DESC_DEFAULT;
> +static uint16_t nb_txd = RTE_TEST_TX_DESC_DEFAULT;
> +
> +static struct rte_eth_conf port_conf = {
> +	.rxmode = {
> +		.split_hdr_size = 0,
> +	},
> +	.txmode = {
> +		.mq_mode = RTE_ETH_MQ_TX_NONE,
> +	},
> +};
> +
> +static uint32_t l2reflect_q;
> +static uint64_t l2reflect_break_usec = DEFAULT_BREAKVAL_USEC;
> +
> +static struct rte_ether_addr ether_bcast_addr = {
> +	.addr_bytes = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }
> +};
> +
> +struct rte_mempool *l2reflect_pktmbuf_pool;
> +
> +static void
> +l2reflect_usage(const char *prgname)
> +{
> +	printf("%s [EAL options] -- [-p PORT] -P [PRIO] [-b USEC] [-n SIZE] [-r] [-f] [-l]"
> +	       "[-q] [-d] [-H USEC] [-B NUM] [-F FILE] [-S] [-i MSEC] [-m] [-c] [-h]\n"
> +	       "  -p PORT: port to configure\n"
> +	       "  -P PRIO: scheduling priority to use\n"
> +	       "  -b USEC: break when latency > USEC\n"
> +	       "  -n SIZE: size of packet in bytes [%i,%i]\n"
> +	       "           (when using jumbo frames, sender and receiver values have to match)\n"
> +	       "  -r: scheduling policy SCHED_RR\n"
> +	       "  -f: scheduling policy SCHED_FIFO\n"
> +	       "  -l: lock memory (mlockall)\n"
> +	       "  -q: quiet, do not print stats\n"
> +#ifdef HAS_SYS_IO
> +	       "  -d: ignore maskable interrupts\n"
> +#endif
> +	       "  -H USEC: create histogram of latencies with USEC time slices\n"
> +	       "  -B NUM: number of histogram buckets\n"
> +	       "  -F FILE: write histogram to file\n"
> +	       "  -S: start processing threads in sleep, wake with SIGCONT\n"
> +	       "  -i MSEC: use interrupts instead of polling (cont. on interrupt or after MSEC)\n"
> +	       "  -m: fake the source mac addr by adding 1 to the last tuple\n"
> +	       "  -c: disable colored output\n"
> +	       "  -h: display help message\n",
> +	       prgname, RTE_ETHER_MIN_LEN, MAX_JUMBO_PKT_LEN);
> +}
> +
> +static int
> +check_opts_for_help(int argc, char **argv, void(*display_help)(const char *))
> +{
> +	if (argc > 2 && !strncmp(argv[1], "--", 3)) {
> +		if (!strncmp(argv[2], "-h", 3) || !strncmp(argv[2], "--help", 7)) {
> +			display_help(argv[0]);
> +			return 1;
> +		}
> +	}
> +	return 0;
> +}
> +
> +/* Parse the argument given in the command line of the application */
> +static int
> +l2reflect_parse_args(int argc, char **argv)
> +{
> +	int opt, ret;
> +	char **argvopt;
> +	int option_index;
> +	int opt_colors = 1;
> +	char *prgname = argv[0];
> +	static struct option lgopts[] = { { NULL, 0, 0, 0 } };
> +
> +	argvopt = argv;
> +	policy = SCHED_OTHER;
> +	hist_filename = NULL;
> +	l2reflect_output_hist = 0;
> +
> +	while ((opt = getopt_long(argc, argvopt, "p:P:b:H:B:F:i:n:qdrflScm", lgopts,
> +				  &option_index)) != EOF) {
> +		switch (opt) {
> +		/* port */
> +		case 'p':
> +			l2reflect_port_number =
> +				(uint16_t)strtoul(optarg, NULL, 10);
> +			break;
> +		case 'P':
> +			priority = strtoul(optarg, NULL, 10);
> +			if (priority > 0) {
> +				if (policy == SCHED_OTHER)
> +					policy = SCHED_RR;
> +				l2reflect_mlock = 1;
> +			}
> +			break;
> +		case 'b':
> +			l2reflect_break_usec = strtoul(optarg, NULL, 10);
> +			break;
> +		case 'S':
> +			sleep_start = 1;
> +			break;
> +		case 'q':
> +			quiet = 1;
> +			break;
> +		case 'd':
> +			disable_int = 1;
> +			break;
> +		case 'r':
> +			policy = SCHED_RR;
> +			break;
> +		case 'f':
> +			policy = SCHED_FIFO;
> +			break;
> +		case 'l':
> +			l2reflect_mlock = 1;
> +			break;
> +		case 'H':
> +			l2reflect_hist = 1;
> +			hist_bucket_usec = strtoul(optarg, NULL, 10);
> +#ifndef RTE_HAS_JANSSON
> +			printf("not compiled with cjson support\n");

s/cjson/jansson/

> +			return -1;
> +#endif
> +			break;
> +		case 'B':
> +			l2reflect_hist_buckets = strtoul(optarg, NULL, 10);
> +			break;
> +		case 'F':
> +			hist_filename = strndup(optarg, 128);
> +			break;
> +		case 'i':
> +			l2reflect_interrupt = 1;
> +			l2reflect_sleep_msec = strtoul(optarg, NULL, 10);
> +			break;
> +		case 'n':
> +			l2reflect_pkt_bytes = strtoull(optarg, NULL, 10);
> +			if (l2reflect_pkt_bytes < RTE_ETHER_MIN_LEN ||
> +			   l2reflect_pkt_bytes > MAX_JUMBO_PKT_LEN) {
> +				printf("packet size %" PRIu64 " not valid\n", l2reflect_pkt_bytes);
> +				return -1;
> +			}
> +			if (l2reflect_pkt_bytes > RTE_MBUF_DEFAULT_DATAROOM) {
> +				printf("NOT IMPLEMENTED. Packet size %" PRIu64 " requires segmented buffers.\n",
> +					l2reflect_pkt_bytes);
> +				return -1;
> +			}
> +			break;
> +		case 'c':
> +			opt_colors = 0;
> +			break;
> +		case 'm':
> +			l2reflect_fake_mac = 1;
> +			break;
> +		default:
> +			l2reflect_usage(prgname);
> +			return -1;
> +		}
> +	}
> +
> +	if (optind >= 0)
> +		argv[optind - 1] = prgname;
> +
> +	if (hist_filename && !l2reflect_hist) {
> +		printf("-F switch requires -H switch as well\n");
> +		return -1;
> +	}
> +
> +	/* output is redirected, disable coloring */
> +	if (!isatty(fileno(stdout)))
> +		opt_colors = 0;
> +
> +	enable_colors(opt_colors);
> +
> +	ret = optind - 1;
> +	optind = 0; /* reset getopt lib */
> +	return ret;
> +}
> +
> +/* Send a burst of one packet */
> +static inline int
> +l2reflect_send_packet(struct rte_mbuf **m, uint16_t port)
> +{
> +	unsigned int ret;
> +	struct rte_ether_hdr *eth;
> +	struct my_magic_packet *pkt;
> +	uint16_t type;
> +
> +	eth = rte_pktmbuf_mtod(*m, struct rte_ether_hdr *);
> +	pkt = (struct my_magic_packet *)eth;
> +	type = pkt->type;
> +
> +	if (likely(type == TRACE_TYPE_DATA))
> +		clock_gettime(CLOCK_MONOTONIC, &last_sent);
> +	ret = rte_eth_tx_burst(port, l2reflect_q, m, 1);
> +	if (unlikely(ret < 1))
> +		rte_pktmbuf_free(*m);
> +	return 0;
> +}
> +
> +static inline void
> +l2reflect_simple_forward(struct rte_mbuf *m)
> +{
> +	struct rte_ether_hdr *eth;
> +	struct my_magic_packet *pkt;
> +
> +	eth = rte_pktmbuf_mtod(m, struct rte_ether_hdr *);
> +	pkt = (struct my_magic_packet *)eth;
> +
> +	/* dst addr */
> +	rte_ether_addr_copy(&eth->src_addr, &eth->dst_addr);
> +	/* src addr */
> +	rte_ether_addr_copy(&l2reflect_port_eth_addr, &eth->src_addr);
> +
> +	if (unlikely(pkt->magic == MAGIC_TRACE_PAYLOAD))
> +		rte_eal_trace_generic_str("sending traced packet");
> +
> +	l2reflect_send_packet(&m, l2reflect_port_number);
> +}
> +
> +static struct rte_mbuf *
> +l2reflect_new_pkt(unsigned int type)
> +{
> +	struct rte_mbuf *m;
> +	struct rte_ether_hdr *eth;
> +	struct my_magic_packet *pkt;
> +	uint64_t frame_bytes = RTE_ETHER_MIN_LEN;
> +
> +	m = rte_pktmbuf_alloc(l2reflect_pktmbuf_pool);
> +	if (m == NULL)
> +		rte_exit(EXIT_FAILURE, "rte_pktmbuf_alloc failed\n");
> +
> +	eth = rte_pktmbuf_mtod(m, struct rte_ether_hdr *);
> +
> +	if (type == TRACE_TYPE_DATA)
> +		frame_bytes = l2reflect_pkt_bytes;
> +
> +	/* zero out packet to make dumps better readable */
> +	memset(eth, 0, frame_bytes - RTE_ETHER_CRC_LEN);
> +
> +	if (type == TRACE_TYPE_HELO)
> +		rte_ether_addr_copy(&ether_bcast_addr, &eth->dst_addr);
> +	else
> +		rte_ether_addr_copy(&l2reflect_remote_eth_addr, &eth->dst_addr);
> +
> +	/* src addr */
> +	rte_ether_addr_copy(&l2reflect_port_eth_addr, &eth->src_addr);
> +	eth->ether_type = rte_cpu_to_be_16(ETHER_TYPE_L2REFLECT);
> +
> +	m->data_len = frame_bytes - RTE_ETHER_CRC_LEN;
> +	m->pkt_len = frame_bytes - RTE_ETHER_CRC_LEN;
> +
> +	pkt = (struct my_magic_packet *)eth;
> +	pkt->type = type;
> +	pkt->breakval = l2reflect_break_usec;
> +	pkt->req_pkt_bytes = l2reflect_pkt_bytes;
> +
> +	return m;
> +}
> +
> +static void
> +l2reflect_send_reset(void)
> +{
> +	struct rte_mbuf *m;
> +	m = l2reflect_new_pkt(TRACE_TYPE_RSET);
> +	l2reflect_send_packet(&m, l2reflect_port_number);
> +}
> +
> +static void
> +l2reflect_send_quit(void)
> +{
> +	struct rte_mbuf *m;
> +	m = l2reflect_new_pkt(TRACE_TYPE_QUIT);
> +	l2reflect_send_packet(&m, l2reflect_port_number);
> +}
> +
> +static void
> +l2reflect_new_ball(void)
> +{
> +	struct rte_mbuf *pnewball;
> +	struct rte_ether_hdr *eth;
> +	struct my_magic_packet *pkt;
> +	char mac_src_str[RTE_ETHER_ADDR_FMT_SIZE];
> +	char mac_dst_str[RTE_ETHER_ADDR_FMT_SIZE];
> +
> +	RTE_LOG(INFO, L2REFLECT, "Should create a packet to play with ...\n");
> +	pnewball = l2reflect_new_pkt(TRACE_TYPE_DATA);
> +
> +	eth = rte_pktmbuf_mtod(pnewball, struct rte_ether_hdr *);
> +
> +	rte_ether_format_addr(mac_src_str, sizeof(mac_src_str), &l2reflect_port_eth_addr);
> +	rte_ether_format_addr(mac_dst_str, sizeof(mac_dst_str), &l2reflect_remote_eth_addr);
> +	RTE_LOG(INFO, L2REFLECT, "from MAC address: %s to %s\n\n", mac_src_str, mac_dst_str);
> +
> +	pkt = (struct my_magic_packet *)eth;
> +
> +	/* we are tracing lets tell the others */
> +	if (l2reflect_break_usec)
> +		pkt->magic = MAGIC_TRACE_PAYLOAD;
> +
> +	l2reflect_send_packet(&pnewball, l2reflect_port_number);
> +}
> +
> +static inline int64_t
> +calcdiff_ns(struct timespec t1, struct timespec t2)
> +{
> +	int64_t diff;
> +	diff = NSEC_PER_SEC * (int64_t)((int)t1.tv_sec - (int)t2.tv_sec);
> +	diff += ((int)t1.tv_nsec - (int)t2.tv_nsec);
> +	return diff;
> +}
> +
> +/* filter the received packets for actual l2reflect messages */
> +static inline unsigned int
> +l2reflect_rx_filter(
> +	struct rte_mbuf *buf)
> +{
> +	struct rte_ether_hdr *eth;
> +	eth = rte_pktmbuf_mtod(buf, struct rte_ether_hdr *);
> +
> +	if (unlikely(buf->nb_segs > 1))
> +		RTE_LOG(WARNING, L2REFLECT, "Segmented packet: data-len: %i, pkt-len: %i, #seg: %i\n",
> +			buf->data_len, buf->pkt_len, buf->nb_segs);
> +
> +	/* check for the l2reflect ether type */
> +	if (unlikely(eth->ether_type != rte_cpu_to_be_16(ETHER_TYPE_L2REFLECT)))
> +		return 0;
> +
> +	/*
> +	 * if the packet is not from our partner
> +	 * (and we already have a partner), drop it
> +	 */
> +	if (unlikely(l2reflect_state != S_ELECT_LEADER &&
> +		!rte_is_same_ether_addr(&eth->src_addr, &l2reflect_remote_eth_addr)))
> +		return 0;
> +
> +	/* filter bounce-back packets */
> +	if (unlikely(rte_is_same_ether_addr(&eth->src_addr, &l2reflect_port_eth_addr)))
> +		return 0;
> +
> +	return 1;
> +}
> +
> +/*
> + * automatically elect the leader of the benchmark by
> + * sending out HELO packets and waiting for responses.
> + * On response, the mac addresses are compared and the
> + * numerically larger one becomes the leader.
> + */
> +static int
> +elect_leader(uint16_t portid)
> +{
> +	struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
> +	struct rte_mbuf *m;
> +	struct rte_ether_hdr *eth;
> +	struct rte_ether_addr *src_addr;
> +	struct rte_eth_dev_info dev_info;
> +	struct my_magic_packet *pkt;
> +	unsigned int i, nb_rx;
> +	int ehlo_send = 0;
> +	int i_win;
> +
> +	while (l2reflect_state == S_ELECT_LEADER) {
> +		/* send a packet to make sure the MAC addr of this interface is publicly known */
> +		m = l2reflect_new_pkt(TRACE_TYPE_HELO);
> +		RTE_LOG(INFO, L2REFLECT, "looking for player HELO\n");
> +		l2reflect_send_packet(&m, l2reflect_port_number);
> +		rte_delay_ms(DELAY_ELECTION_MS);
> +
> +		/* receive election packets */
> +		nb_rx = rte_eth_rx_burst(portid, l2reflect_q, pkts_burst,
> +					 MAX_PKT_BURST);
> +
> +		/* note: do not short-circuit as otherwise the mbufs are not freed */
> +		for (i = 0; i < nb_rx; i++) {
> +			m = pkts_burst[i];
> +			eth = rte_pktmbuf_mtod(m, struct rte_ether_hdr *);
> +			src_addr = &eth->src_addr;
> +			pkt = (struct my_magic_packet *)eth;
> +
> +			if (!l2reflect_rx_filter(m)) {
> +				rte_pktmbuf_free(m);
> +				continue;
> +			}
> +
> +			if (pkt->type == TRACE_TYPE_EHLO && l2reflect_state == S_ELECT_LEADER) {
> +				/* check if both modes are equal */
> +				if (((l2reflect_pkt_bytes <= RTE_ETHER_MTU)
> +				   != (pkt->req_pkt_bytes <= RTE_ETHER_MTU))) {
> +					l2reflect_state = S_LOCAL_TERM;
> +					m = l2reflect_new_pkt(TRACE_TYPE_QUIT);
> +					l2reflect_send_packet(&m, l2reflect_port_number);
> +					rte_exit(EXIT_FAILURE,
> +						"remote and local jumbo config does not match "
> +						"(%" PRIu64 " vs %" PRIu64 ")\n",
> +						l2reflect_pkt_bytes, pkt->req_pkt_bytes);
> +				}
> +				if (l2reflect_pkt_bytes != pkt->req_pkt_bytes) {
> +					l2reflect_pkt_bytes = MAX(l2reflect_pkt_bytes,
> +								  pkt->req_pkt_bytes);
> +					rte_eth_dev_info_get(l2reflect_port_number, &dev_info);
> +					const uint32_t overhead_len = eth_dev_get_overhead_len(
> +									dev_info.max_rx_pktlen,
> +									dev_info.max_mtu);
> +					const uint16_t mtu = MAX(l2reflect_pkt_bytes - overhead_len,
> +								 dev_info.min_mtu);
> +					RTE_LOG(INFO, L2REFLECT,
> +						"update frame sizes: frame: %" PRIu64 ", MTU %d\n",
> +						l2reflect_pkt_bytes, mtu);
> +					const int ret = rte_eth_dev_set_mtu(
> +								l2reflect_port_number,
> +								mtu);
> +					if (ret < 0)
> +						rte_exit(EXIT_FAILURE, "failed to update MTU: %s\n",
> +								 strerror(-ret));
> +				}
> +
> +				if (ehlo_send) {
> +					l2reflect_state = S_RUNNING;
> +					RTE_LOG(INFO, L2REFLECT, "Enter running state\n");
> +				}
> +			}
> +			/* we got a HELO packet, respond with EHLO */
> +			if (pkt->type == TRACE_TYPE_HELO) {
> +				char mac_str_other[RTE_ETHER_ADDR_FMT_SIZE];
> +				rte_ether_addr_copy(src_addr, &l2reflect_remote_eth_addr);
> +				m = l2reflect_new_pkt(TRACE_TYPE_EHLO);
> +				rte_ether_format_addr(
> +				  mac_str_other, sizeof(mac_str_other), &l2reflect_remote_eth_addr);
> +				RTE_LOG(INFO, L2REFLECT, "found one HELO from %s\n", mac_str_other);
> +				l2reflect_send_packet(&m, l2reflect_port_number);
> +				ehlo_send = 1;
> +			}
> +			rte_pktmbuf_free(m);

The loop content could be moved in a dedicated function, it would
improve the readability.

> +		}
> +	}
> +
> +	if (rte_is_same_ether_addr(&l2reflect_port_eth_addr, &l2reflect_remote_eth_addr))
> +		rte_exit(EXIT_FAILURE, "talking to myself ... confused\n");
> +
> +	/* the one with the bigger MAC is the leader */
> +	i_win = ((*((uint64_t *)&l2reflect_port_eth_addr)   & MAC_ADDR_CMP) >
> +			 (*((uint64_t *)&l2reflect_remote_eth_addr) & MAC_ADDR_CMP));
> +
> +	RTE_LOG(INFO, L2REFLECT, "i am the \"%s\"\n", i_win ? "rick" : "morty");
> +
> +	return i_win;
> +}
> +
> +/*
> + * add the measured time diff to the statistics.
> + * return false if threshold is hit
> + */
> +static inline int
> +add_to_record(const uint64_t diff)
> +{
> +	record.rounds++;
> +	/* do not count the first rounds, diff would be too high */
> +	if (record.rounds < WARMUP_ROUNDS)
> +		return 1;
> +
> +	if (l2reflect_hist) {
> +		const uint64_t bucket =
> +			MIN(diff / (hist_bucket_usec * 1000), l2reflect_hist_buckets-1);
> +		record.hist[bucket]++;
> +	}
> +
> +	record.avg_round_ns += (double)diff;
> +	if (diff < record.min_round_ns)
> +		record.min_round_ns = diff;
> +	if (diff > record.max_round_ns) {
> +		record.max_round_ns = diff;
> +		if (l2reflect_break_usec &&
> +		   (record.max_round_ns > (l2reflect_break_usec * 1000)))
> +			return 0;
> +	}
> +	return 1;
> +}
> +
> +/*
> + * process a single packet.
> + * return false if latency threshold is hit
> + */
> +static inline int
> +process_packet(
> +	struct my_magic_packet *pkt,
> +	struct timespec *rx_time,
> +	uint64_t *diff)
> +{
> +	if (pkt->type == TRACE_TYPE_DATA) {
> +		rte_memcpy(&last_recv, rx_time, sizeof(*rx_time));
> +		*diff = calcdiff_ns(last_recv, last_sent);
> +		if (!unlikely(add_to_record(*diff))) {
> +			/* TODO: improve tracing */
> +			rte_eal_trace_generic_u64(record.max_round_ns / 1000);
> +			return 0;
> +		}
> +	}
> +	if (pkt->magic == MAGIC_TRACE_PAYLOAD)
> +		rte_eal_trace_generic_str("received traced packet");
> +
> +	return 1;
> +}
> +
> +/*
> + * free all packet buffers in the range [begin, end[.
> + */
> +static void
> +free_pktbufs(
> +		struct rte_mbuf **bufs,
> +		int begin,
> +		int end)
> +{
> +	int i = begin;
> +	for (; i < end; i++)
> +		rte_pktmbuf_free(bufs[0]);

rte_pktmbuf_free(bufs[i]) ?

> +}
> +
> +/*
> + * return 1 in case the ball was lost (cheap check)
> + */
> +static inline void
> +check_ball_lost(const uint64_t dp_idle) {
> +	/* only check if we are in running state and have a breakval */
> +	if (unlikely(dp_idle & RX_TIMEOUT_MASK) &&
> +	   l2reflect_state == S_RUNNING &&
> +	   l2reflect_break_usec &&
> +	   record.rounds > WARMUP_ROUNDS) {
> +		RTE_LOG(INFO, L2REFLECT, "lost ball after %" PRIu64 " rounds\n", record.rounds);
> +		l2reflect_state = S_LOCAL_TERM;
> +	}
> +}
> +
> +/* main processing loop */
> +static void
> +l2reflect_main_loop(void)
> +{
> +	struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
> +	struct rte_mbuf *m;
> +	unsigned int lcore_id;
> +	unsigned int j, nb_rx, nb_evt;
> +	uint16_t portid;
> +	/* number of consequent idle passes */
> +	uint64_t dp_idle = 0;
> +	uint64_t diff = 0;
> +	int sender;
> +	struct my_magic_packet *pkt;
> +	struct rte_ether_hdr *eth;
> +	struct rte_epoll_event event;
> +
> +	lcore_id = rte_lcore_id();
> +
> +	RTE_LOG(INFO, L2REFLECT, "entering main loop on lcore %u\n", lcore_id);
> +
> +	portid = l2reflect_port_number;
> +	RTE_LOG(INFO, L2REFLECT, " -- lcoreid=%u portid=%u\n", lcore_id,
> +		portid);
> +	assert_link_status(portid);
> +
> +restart:
> +	init_record();
> +	rte_eth_stats_reset(portid);
> +	l2reflect_state = S_ELECT_LEADER;
> +	sender = elect_leader(portid);
> +
> +	if (l2reflect_break_usec)
> +		rte_eal_trace_generic_str("hit breakval");
> +
> +	/* the leader election implements a latch (half-barrier).
> +	 * To ensure that the other party is in running state, we
> +	 * have to wait at least a full election period
> +	 */
> +	rte_delay_ms(DELAY_ELECTION_MS * 2);
> +
> +	/* we are the sender so we bring one ball into the game */
> +	if (sender)
> +		l2reflect_new_ball();
> +
> +	/* reset the record */
> +	init_record();
> +	while (l2reflect_state == S_RUNNING) {
> +		struct timespec rx_time;
> +
> +		if (l2reflect_interrupt) {
> +			rte_eth_dev_rx_intr_enable(portid, l2reflect_q);
> +			/* wait for interrupt or timeout */
> +			nb_evt = rte_epoll_wait(RTE_EPOLL_PER_THREAD, &event, 1,
> +						l2reflect_sleep_msec);
> +			rte_eth_dev_rx_intr_disable(portid, l2reflect_q);
> +			if (nb_evt == 0 && rounds > WARMUP_ROUNDS)
> +				++record.timeouts;
> +		}
> +
> +		nb_rx = rte_eth_rx_burst(portid, l2reflect_q, pkts_burst,
> +					 MAX_PKT_BURST);
> +
> +		if (nb_rx) {
> +			clock_gettime(CLOCK_MONOTONIC, &rx_time);
> +			dp_idle = 0;
> +		} else
> +			++dp_idle;
> +
> +		for (j = 0; j < nb_rx; j++) {
> +			m = pkts_burst[j];
> +			eth = rte_pktmbuf_mtod(m, struct rte_ether_hdr *);
> +			pkt = (struct my_magic_packet *)eth;
> +
> +			rte_prefetch0(eth);
> +
> +			if (unlikely(!l2reflect_rx_filter(m))) {
> +				rte_pktmbuf_free(m);
> +				continue;
> +			}
> +
> +			/* remote is telling us to reset or stop */
> +			if (unlikely(pkt->type == TRACE_TYPE_RSET)) {
> +				free_pktbufs(pkts_burst, j, nb_rx);
> +				goto restart;
> +			}
> +			if (unlikely(pkt->type == TRACE_TYPE_QUIT)) {
> +				l2reflect_state = S_REMOTE_TERM;
> +				free_pktbufs(pkts_burst, j, nb_rx);
> +				break;
> +			}
> +
> +			if (likely(l2reflect_state == S_RUNNING)) {
> +				if (unlikely(!process_packet(pkt, &rx_time, &diff))) {
> +					l2reflect_state = S_LOCAL_TERM;
> +					free_pktbufs(pkts_burst, j, nb_rx);
> +					break;
> +				}
> +				l2reflect_simple_forward(m);
> +			}
> +		}
> +		check_ball_lost(dp_idle);
> +	}
> +
> +	const int state_cpy = l2reflect_state;
> +	switch (state_cpy) {
> +	case S_RESET_TRX:
> +		l2reflect_send_reset();
> +		l2reflect_state = S_ELECT_LEADER;
> +		/* fallthrough */
> +	case S_ELECT_LEADER:
> +		goto restart;
> +	}
> +
> +	if (state_cpy == S_LOCAL_TERM) {
> +		rte_eal_trace_generic_str("local termination");
> +		l2reflect_send_quit();
> +	} else if (state_cpy == S_REMOTE_TERM) {
> +		RTE_LOG(INFO, L2REFLECT, "received message that remote hit threshold (or is cancelled)\n");
> +	}
> +}
> +
> +static int
> +l2reflect_launch_one_lcore(__rte_unused void *dummy)
> +{
> +	struct sched_param param;
> +	int err;
> +
> +	if (sleep_start) {
> +		RTE_LOG(INFO, L2REFLECT, "Sleeping and waiting for SIGCONT\n");
> +		while (sleep_start) {
> +			rte_delay_ms(10);
> +			if (l2reflect_state == S_LOCAL_TERM)
> +				rte_exit(EXIT_SUCCESS, "Quit\n");
> +		}
> +		RTE_LOG(INFO, L2REFLECT, "Got SIGCONT, continuing");
> +	}
> +	if (l2reflect_mlock) {
> +		err = mlockall(MCL_CURRENT | MCL_FUTURE);
> +		if (err)
> +			rte_exit(EXIT_FAILURE, "mlockall failed: %s\n",
> +				 strerror(errno));
> +	}
> +	if (priority > 0 || policy != SCHED_OTHER) {
> +		memset(&param, 0, sizeof(param));
> +		param.sched_priority = priority;
> +		err = sched_setscheduler(0, policy, &param);
> +		if (err)
> +			rte_exit(EXIT_FAILURE,
> +				 "sched_setscheduler failed: %s\n",
> +				 strerror(errno));
> +	}
> +	if (l2reflect_interrupt) {
> +		err = rte_eth_dev_rx_intr_ctl_q(l2reflect_port_number,
> +						l2reflect_q,
> +						RTE_EPOLL_PER_THREAD,
> +						RTE_INTR_EVENT_ADD, NULL);
> +		if (err)
> +			rte_exit(EXIT_FAILURE,
> +				 "could not register I/O interrupt\n");
> +	}
> +	l2reflect_main_loop();
> +	return 0;
> +}
> +
> +static void
> +sig_handler(int signum)
> +{
> +	switch (signum) {
> +	case SIGUSR1:
> +		if (l2reflect_state == S_RUNNING)
> +			l2reflect_state = S_RESET_TRX;
> +		break;
> +	case SIGUSR2:
> +		l2reflect_output_hist = 1;
> +		break;
> +	case SIGCONT:
> +		sleep_start = 0;
> +		break;
> +	case SIGHUP:
> +	case SIGINT:
> +		l2reflect_state = S_LOCAL_TERM;
> +		break;
> +	}
> +}
> +
> +int
> +main(int argc, char **argv)
> +{
> +	struct rte_eth_dev_info dev_info;
> +	struct rte_eth_txconf txconf;
> +	int ret;
> +	uint32_t i;
> +	uint16_t nb_ports;
> +	unsigned int lcore_id;
> +	struct sigaction action;
> +	bzero(&action, sizeof(action));
> +	char mempool_name[128];
> +	char mac_str[RTE_ETHER_ADDR_FMT_SIZE];
> +
> +	action.sa_handler = sig_handler;
> +	if (sigaction(SIGHUP, &action, NULL) < 0 ||
> +	    sigaction(SIGUSR1, &action, NULL) < 0 ||
> +	    sigaction(SIGUSR2, &action, NULL) < 0 ||
> +	    sigaction(SIGCONT, &action, NULL) < 0 ||
> +	    sigaction(SIGINT, &action, NULL) < 0) {
> +		rte_exit(EXIT_FAILURE, "Could not register signal handler\n");
> +	}
> +
> +	lcore_id = rte_lcore_id();
> +
> +	if (check_opts_for_help(argc, argv, l2reflect_usage))
> +		return 0;
> +
> +	/* init EAL */
> +	ret = rte_eal_init(argc, argv);
> +	if (ret < 0)
> +		rte_exit(EXIT_FAILURE, "Invalid EAL arguments\n");
> +	argc -= ret;
> +	argv += ret;
> +
> +	/* parse application arguments (after the EAL ones) */
> +	ret = l2reflect_parse_args(argc, argv);
> +	if (ret < 0)
> +		rte_exit(EXIT_FAILURE, "Invalid L2REFLECT arguments\n");
> +
> +	snprintf(mempool_name, sizeof(mempool_name), "mbuf_pool_%d", getpid());
> +	RTE_LOG(DEBUG, L2REFLECT, "About to create mempool \"%s\"\n", mempool_name);
> +	/* create the mbuf pool */
> +	l2reflect_pktmbuf_pool =
> +		rte_pktmbuf_pool_create(mempool_name, NB_MBUF,
> +			MAX_PKT_BURST, 0, RTE_MBUF_DEFAULT_BUF_SIZE,
> +			rte_socket_id());
> +
> +	if (l2reflect_pktmbuf_pool == NULL)
> +		rte_exit(EXIT_FAILURE,
> +			 "Cannot init/find mbuf pool name %s\nError: %d %s\n",
> +			 mempool_name, rte_errno, rte_strerror(rte_errno));
> +
> +	nb_ports = rte_eth_dev_count_avail();
> +	if (nb_ports == 0)
> +		rte_exit(EXIT_FAILURE, "No Ethernet ports - bye\n");
> +	if (l2reflect_port_number + 1 > nb_ports)
> +		rte_exit(EXIT_FAILURE, "Chosen port %d does not exist - bye\n",
> +			 l2reflect_port_number);
> +	RTE_LOG(INFO, L2REFLECT, "We have %d ports and will use port %d\n", nb_ports,
> +	       l2reflect_port_number);
> +
> +	rte_eth_dev_info_get(l2reflect_port_number, &dev_info);
> +	RTE_LOG(INFO, L2REFLECT, "Initializing port %u ...\n", l2reflect_port_number);
> +	fflush(stdout);
> +
> +	if (l2reflect_interrupt)
> +		port_conf.intr_conf.rxq = 1;
> +
> +	ret = config_port_max_pkt_len(&port_conf, &dev_info);
> +	if (ret < 0)
> +		rte_exit(EXIT_FAILURE,
> +			"Invalid max packet length: %u (port %u)\n",
> +			l2reflect_port_number, l2reflect_port_number);
> +
> +	ret = rte_eth_dev_configure(l2reflect_port_number, 1, 1, &port_conf);
> +	if (ret < 0)
> +		rte_exit(EXIT_FAILURE,
> +			"Cannot configure device: err=%s, port=%u\n",
> +			strerror(-ret), l2reflect_port_number);
> +
> +	ret = rte_eth_dev_adjust_nb_rx_tx_desc(l2reflect_port_number, &nb_rxd, &nb_txd);
> +	if (ret != 0)
> +		rte_exit(EXIT_FAILURE,
> +			 "Cannot adjust # of Rx/Tx descriptors to HW limits: err=%s, port=%u\n",
> +			 strerror(-ret), l2reflect_port_number);
> +
> +	/* init RX queues */
> +	for (i = 0; i <= l2reflect_q; i++) {
> +		ret = rte_eth_rx_queue_setup(
> +			l2reflect_port_number, i, nb_rxd,
> +			rte_eth_dev_socket_id(l2reflect_port_number), NULL,
> +			l2reflect_pktmbuf_pool);
> +		if (ret < 0)
> +			rte_exit(
> +				EXIT_FAILURE,
> +				"rte_eth_rx_queue_setup:err=%s, port=%u q=%u\n",
> +				strerror(-ret), l2reflect_port_number, i);
> +	}
> +
> +	/* init one TX queue on each port */
> +	txconf = dev_info.default_txconf;
> +	txconf.offloads = port_conf.txmode.offloads;
> +	ret = rte_eth_tx_queue_setup(
> +		l2reflect_port_number, 0, nb_txd,
> +		rte_eth_dev_socket_id(l2reflect_port_number), &txconf);
> +	if (ret < 0)
> +		rte_exit(EXIT_FAILURE,
> +			 "rte_eth_tx_queue_setup:err=%s, port=%u\n",
> +			 strerror(-ret), (unsigned int)l2reflect_port_number);
> +
> +	/* Start device */
> +	ret = rte_eth_dev_start(l2reflect_port_number);
> +	if (ret < 0)
> +		rte_exit(EXIT_FAILURE, "rte_eth_dev_start:err=%s, port=%u\n",
> +			 strerror(-ret), (unsigned int)l2reflect_port_number);
> +
> +	rte_eth_macaddr_get(l2reflect_port_number, &l2reflect_port_eth_addr);
> +
> +	/*
> +	 * When running on a Tap device, we might want to use a foreign
> +	 * mac address to make sure that the application and the Tap device
> +	 * do not share the same MAC addr. By that, we enforce that the
> +	 * bridge learns this address and correctly forwards unicast packets.
> +	 */
> +	if (l2reflect_fake_mac)
> +		l2reflect_port_eth_addr.addr_bytes[5] += 1;
> +
> +	rte_ether_format_addr(mac_str, sizeof(mac_str),
> +			      &l2reflect_port_eth_addr);
> +	RTE_LOG(INFO, L2REFLECT, "Port %u, MAC address: %s\n\n",
> +	       (unsigned int)l2reflect_port_number, mac_str);
> +
> +	/*
> +	 * in quiet mode the primary executes the main packet loop
> +	 * otherwise the one worker does it and the primary prints stats
> +	 */
> +	if (quiet) {
> +		assert(rte_lcore_count() == 1);
> +#ifdef HAS_SYS_IO
> +		if (disable_int) {
> +			iopl(3);
> +			asm("cli");
> +		}
> +#endif
> +		RTE_LOG(INFO, L2REFLECT, "PID %i, Parent %i\n", getpid(), getppid());
> +		l2reflect_launch_one_lcore(NULL);
> +	} else {
> +		assert(rte_lcore_count() == 2);
> +		/* the worker reflects the packets */
> +		RTE_LCORE_FOREACH_WORKER(lcore_id)
> +		{
> +			rte_eal_remote_launch(l2reflect_launch_one_lcore, NULL,
> +					      lcore_id);
> +		}
> +
> +		/* the primary prints the stats */
> +		init_record();
> +		l2reflect_stats_loop();
> +		rte_eal_mp_wait_lcore();
> +	}
> +	rte_eal_cleanup();
> +
> +	if (l2reflect_hist)
> +		output_histogram_snapshot();
> +
> +	cleanup_record();
> +
> +	return 0;
> +}
> diff --git a/app/l2reflect/meson.build b/app/l2reflect/meson.build
> new file mode 100644
> index 0000000000..14b154ef06
> --- /dev/null
> +++ b/app/l2reflect/meson.build
> @@ -0,0 +1,21 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2022 Siemens AG
> +
> +cc = meson.get_compiler('c')
> +
> +jansson = dependency('libjansson', required: false)
> +
> +if not jansson.found()
> +    jansson = cc.find_library('jansson', required: false)
> +endif
> +
> +if cc.has_header('sys/io.h')
> +    cflags += '-DHAS_SYS_IO'
> +endif
> +
> +sources = files('main.c', 'utils.c', 'stats.c', 'colors.c')
> +deps += ['ethdev']

I think some dependecies are missing:
ring, mbuf, mempool

> +if jansson.found()
> +    ext_deps += jansson
> +    cflags += '-DRTE_HAS_JANSSON'
> +endif
> diff --git a/app/l2reflect/payload.h b/app/l2reflect/payload.h
> new file mode 100644
> index 0000000000..c1fae5d5e4
> --- /dev/null
> +++ b/app/l2reflect/payload.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2022 Siemens AG
> + */
> +#include <rte_ether.h>
> +
> +#ifndef _L2REFLECT_PAYLOAD_H_
> +#define _L2REFLECT_PAYLOAD_H_
> +
> +#define MAGIC_TRACE_PAYLOAD 0xd00faffeaffed00full
> +/* IEEE Std 802 - Local Experimental Ethertype */
> +#define ETHER_TYPE_L2REFLECT 0x88B5
> +
> +struct my_magic_packet {
> +	/* l2 packet header */
> +	struct rte_ether_hdr eth;
> +	/* type of the l2reflect packet */
> +	uint8_t type;
> +	/* magic easy-to-spot pattern for tracing */
> +	uint64_t magic;
> +	/* break if latency is larger than this */
> +	uint64_t breakval;
> +	/* intended size of the packet */
> +	uint64_t req_pkt_bytes;
> +};
> +
> +#endif /* _L2REFLECT_PAYLOAD_H_ */
> diff --git a/app/l2reflect/stats.c b/app/l2reflect/stats.c
> new file mode 100644
> index 0000000000..6bcbb7a2bf
> --- /dev/null
> +++ b/app/l2reflect/stats.c
> @@ -0,0 +1,225 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + */
> +#include <stdio.h>
> +#include <sys/types.h>
> +#include <unistd.h>
> +#include <time.h>
> +#include <string.h>
> +#ifdef RTE_HAS_JANSSON
> +#include <jansson.h>
> +#endif
> +#include "colors.h"
> +#include "stats.h"
> +
> +unsigned int hist_bucket_usec;
> +struct stats record;
> +char *hist_filename;
> +
> +void
> +init_record(void)
> +{
> +	record.max_round_ns = 0;
> +	record.min_round_ns = MIN_INITIAL;
> +	record.rounds = 0;
> +	record.timeouts = 0;
> +	record.avg_round_ns = 0;
> +	if (l2reflect_hist) {
> +		if (!record.hist_size) {
> +			record.hist =
> +				calloc(l2reflect_hist_buckets, sizeof(uint64_t));
> +			record.hist_size = l2reflect_hist_buckets;
> +		} else {
> +			memset(record.hist, 0,
> +			       record.hist_size * sizeof(uint64_t));
> +		}
> +	}
> +	clock_gettime(CLOCK_MONOTONIC, &record.time_start);
> +}
> +
> +void
> +cleanup_record(void)
> +{
> +	if (l2reflect_hist) {
> +		free(record.hist);
> +		record.hist = NULL;
> +		record.hist_size = 0;
> +	}
> +}
> +
> +void
> +output_histogram_snapshot(void)
> +{
> +	char *json = serialize_histogram(&record);
> +	FILE *fd = stderr;
> +	if (hist_filename)
> +		fd = fopen(hist_filename, "w");
> +	fputs(json, fd);
> +	fputs("\n", fd);
> +	free(json);
> +	if (hist_filename)
> +		fclose(fd);
> +}
> +
> +void
> +print_stats(void)
> +{
> +	const char clr[] = { 27, '[', '2', 'J', '\0' };
> +	const char topLeft[] = { 27, '[', '1', ';', '1', 'H', '\0' };
> +	const uint64_t bytes_in_gib = 0x40000000;
> +	struct rte_eth_stats stats;
> +	char mac_str_me[RTE_ETHER_ADDR_FMT_SIZE];
> +	char mac_str_remote[RTE_ETHER_ADDR_FMT_SIZE];
> +	char timeout_bound_str[32];
> +	const char *str_jumbo = l2reflect_pkt_bytes > RTE_ETHER_MTU ?
> +		"jumbo" : "no-jumbo";
> +	struct timespec time_now;
> +
> +	if (l2reflect_interrupt == 0)
> +		snprintf(timeout_bound_str, sizeof(timeout_bound_str), "     polling");
> +	else if (l2reflect_sleep_msec == -1u)
> +		snprintf(timeout_bound_str, sizeof(timeout_bound_str), ">=  infinite");
> +	else
> +		snprintf(timeout_bound_str, sizeof(timeout_bound_str), ">%9" PRIu64 "ms",
> +			l2reflect_sleep_msec);
> +
> +	rte_eth_stats_get(l2reflect_port_number, &stats);
> +	rte_ether_format_addr(mac_str_me, sizeof(mac_str_me),
> +			      &l2reflect_port_eth_addr);
> +	rte_ether_format_addr(mac_str_remote, sizeof(mac_str_remote),
> +			      &l2reflect_remote_eth_addr);
> +
> +	clock_gettime(CLOCK_MONOTONIC, &time_now);
> +	const uint64_t time_since_start = time_now.tv_sec - record.time_start.tv_sec;
> +
> +	/* Clear screen and move to top left */
> +	printf("%s%s", clr, topLeft);
> +
> +	printf("%sNetworking Roundtrip Test%s\n", colors->green, colors->reset);
> +	printf("\n%sPort statistics ====================================%s",
> +	       colors->magenta, colors->reset);
> +
> +	printf("\nMe: %s <--> Remote: %s", mac_str_me, mac_str_remote);
> +	printf("\nStatistics for port %d PID %d on lcore %d ---------"
> +			"\nState: %-16s %10" PRIu64 " s"
> +			"\nPackets tx: %22" PRIu64 "\nPackets rx: %22" PRIu64
> +			"\nBytes tx: %24" PRIu64 "    (%8.2f GiB)"
> +			"\nBytes rx: %24" PRIu64 "    (%8.2f GiB)"
> +			"\nErrors tx: %23" PRIu64 "\nErrors rx: %23" PRIu64
> +			"\nTimeouts rx: %21" PRIu64 "    (%s)"
> +			"\nPacketsize [Byte]: %15" PRIu64 "    (%12s)",
> +			l2reflect_port_number, getpid(), rte_lcore_id(),
> +			runstate_tostring(l2reflect_state),
> +			time_since_start,
> +			stats.opackets, stats.ipackets, stats.obytes,
> +			(double)stats.obytes / bytes_in_gib, stats.ibytes,
> +			(double)stats.ibytes / bytes_in_gib, stats.oerrors,
> +			stats.ierrors, record.timeouts,
> +			timeout_bound_str, l2reflect_pkt_bytes, str_jumbo);
> +	printf("\n%sPort timing statistics =============================%s",
> +	       colors->magenta, colors->reset);
> +	if (l2reflect_state == S_ELECT_LEADER ||
> +		record.min_round_ns == MIN_INITIAL) {
> +		printf("\n\nBenchmark not started yet...\n");
> +	} else {
> +		printf("\n%sMax%s roundtrip: %19" PRIu64 " us", colors->red,
> +		       colors->reset, record.max_round_ns / 1000);
> +		printf("\n%sAvg%s roundtrip: %19" PRIu64 " us", colors->yellow,
> +		       colors->reset,
> +		       record.rounds ? (uint64_t)(record.avg_round_ns /
> +						  record.rounds / 1000) :
> +				       0);
> +		printf("\n%sMin%s roundtrip: %19" PRIu64 " us", colors->green,
> +		       colors->reset, record.min_round_ns / 1000);
> +	}
> +	printf("\n%s====================================================%s\n",
> +	       colors->magenta, colors->reset);
> +}
> +
> +void
> +l2reflect_stats_loop(void)
> +{
> +	while (!(l2reflect_state & (S_LOCAL_TERM | S_REMOTE_TERM))) {
> +		print_stats();
> +		if (l2reflect_hist && l2reflect_output_hist) {
> +			output_histogram_snapshot();
> +			l2reflect_output_hist = 0;
> +		}
> +		rte_delay_us_sleep(1000000);
> +	}
> +}
> +
> +char *
> +serialize_histogram(__rte_unused const struct stats *record)
> +{
> +#ifndef RTE_HAS_JANSSON
> +	return strdup("to print histogram, build with jansson support");
> +#else
> +	char *str = NULL;
> +	char key[8];
> +	unsigned int i;
> +	json_t *hist0, *cpu0, *all_cpus, *output;
> +
> +	output = json_object();
> +	/* version: 1 */
> +	json_object_set_new(output, "version", json_integer(1));
> +
> +	/* cpu 0 histogram */
> +	hist0 = json_object();
> +	for (i = 0; i < record->hist_size; ++i) {
> +		/* only log positive numbers to meet jitterplot format */
> +		if (record->hist[i] != 0) {
> +			snprintf(key, 8, "%u", i * hist_bucket_usec);
> +			json_object_set(hist0, key,
> +					json_integer(record->hist[i]));
> +		}
> +	}
> +
> +	/* in case of empty histogram, set these values to zero */
> +	const json_int_t min_round_us =
> +		record->rounds ? record->min_round_ns / 1000 : 0;
> +	const json_int_t avg_round_us =
> +		record->rounds ? record->avg_round_ns / record->rounds / 1000 : 0;
> +	const json_int_t max_round_us =
> +		record->rounds ? record->max_round_ns / 1000 : 0;
> +
> +	/* cpu 0 stats */
> +	cpu0 = json_object();
> +	json_object_set_new(cpu0, "histogram", hist0);
> +	json_object_set_new(cpu0, "count", json_integer(record->rounds));
> +	json_object_set_new(cpu0, "min", json_integer(min_round_us));
> +	json_object_set_new(cpu0, "max", json_integer(max_round_us));
> +	json_object_set_new(cpu0, "avg", json_integer(avg_round_us));
> +
> +	/* combine objects */
> +	all_cpus = json_object();
> +	json_object_set_new(all_cpus, "0", cpu0);
> +	json_object_set_new(output, "cpu", all_cpus);
> +
> +	str = json_dumps(output, JSON_ENSURE_ASCII | JSON_INDENT(2));
> +
> +	/* cleanup */
> +	json_decref(output);
> +
> +	return str;
> +#endif
> +}
> +
> +const char *
> +runstate_tostring(int s)
> +{
> +	switch (s) {
> +	case S_ELECT_LEADER:
> +		return "Electing";
> +	case S_RESET_TRX:
> +		return "Resetting";
> +	case S_RUNNING:
> +		return "Running";
> +	case S_LOCAL_TERM:
> +		return "Term. local";
> +	case S_REMOTE_TERM:
> +		return "Term. remote";
> +	default:
> +		return "Preparing";
> +	}
> +}
> diff --git a/app/l2reflect/stats.h b/app/l2reflect/stats.h
> new file mode 100644
> index 0000000000..7f3dd9fffb
> --- /dev/null
> +++ b/app/l2reflect/stats.h
> @@ -0,0 +1,67 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + */
> +#ifndef _L2REFLECT_STATS_H_
> +#define _L2REFLECT_STATS_H_
> +#include <stdint.h>
> +#include <stdatomic.h>
> +#include <limits.h>
> +
> +#include <rte_ethdev.h>
> +
> +#include "l2reflect.h"
> +
> +#define MIN_INITIAL ULONG_MAX
> +#define HIST_NUM_BUCKETS_DEFAULT 128
> +
> +/* runtime statistics */
> +struct stats {
> +	uint64_t max_round_ns;
> +	uint64_t min_round_ns;
> +	uint64_t rounds;
> +	uint64_t timeouts;
> +	double avg_round_ns;
> +	unsigned int hist_size;
> +	/* each slot is 10us */
> +	uint64_t *hist;
> +	struct timespec time_start;
> +};
> +
> +/* size of each histogram bucket in usec */
> +extern unsigned int hist_bucket_usec;
> +extern struct stats record;
> +extern char *hist_filename;
> +
> +void
> +init_record(void);
> +void
> +cleanup_record(void);
> +
> +void
> +l2reflect_stats_loop(void);
> +
> +/*
> + * Write the histogram to file / stdio without any locking.
> + * When called during the measurement, values are approximations
> + * (racy reads).
> + */
> +void
> +output_histogram_snapshot(void);
> +
> +/* Print out statistics on packets dropped */
> +void
> +print_stats(void);
> +
> +/*
> + * get a JSON representation of the record
> + */
> +char *
> +serialize_histogram(const struct stats *record);
> +
> +/*
> + * get a string representation of the current runstate
> + */
> +const char *
> +runstate_tostring(int s);
> +
> +#endif /* _L2REFLECT_STATS_H_ */
> diff --git a/app/l2reflect/utils.c b/app/l2reflect/utils.c
> new file mode 100644
> index 0000000000..4116b986d2
> --- /dev/null
> +++ b/app/l2reflect/utils.c
> @@ -0,0 +1,67 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2021 Siemens AG
> + */
> +
> +#include <rte_ethdev.h>
> +#include <rte_log.h>
> +#include <rte_ethdev.h>
> +
> +#include "utils.h"
> +#include "l2reflect.h"
> +
> +void
> +assert_link_status(int port_id)
> +{
> +	struct rte_eth_link link;
> +	uint8_t rep_cnt = MAX_REPEAT_TIMES;
> +	int link_get_err = -EINVAL;
> +
> +	memset(&link, 0, sizeof(link));
> +	do {
> +		link_get_err = rte_eth_link_get_nowait(port_id, &link);
> +		if (link_get_err == 0 && link.link_status == RTE_ETH_LINK_UP)
> +			break;
> +		rte_delay_ms(CHECK_INTERVAL);
> +		RTE_LOG(INFO, L2REFLECT, "Link not ready yet, try again...\n");
> +	} while (--rep_cnt && (l2reflect_state != S_LOCAL_TERM));
> +
> +	if (link_get_err < 0)
> +		rte_exit(EXIT_FAILURE, "error: link get is failing: %s\n",
> +			 rte_strerror(-link_get_err));
> +	if (link.link_status == RTE_ETH_LINK_DOWN)
> +		rte_exit(EXIT_FAILURE, "error: link is still down\n");
> +
> +	const char *linkspeed_str = rte_eth_link_speed_to_str(link.link_speed);
> +	RTE_LOG(INFO, L2REFLECT,
> +		"Link status on port %d: speed: %s, duplex: %s\n",
> +		port_id, linkspeed_str,
> +		link.link_duplex == RTE_ETH_LINK_FULL_DUPLEX ? "full" : "half");
> +}
> +
> +uint32_t
> +eth_dev_get_overhead_len(uint32_t max_rx_pktlen, uint16_t max_mtu)
> +{
> +	uint32_t overhead_len;
> +	if (max_mtu != UINT16_MAX && max_rx_pktlen > max_mtu)
> +		overhead_len = max_rx_pktlen - max_mtu;
> +	else
> +		overhead_len = RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
> +	return overhead_len;
> +}
> +
> +int
> +config_port_max_pkt_len(struct rte_eth_conf *conf,
> +						struct rte_eth_dev_info *dev_info)
> +{
> +	uint32_t overhead_len;
> +	if (l2reflect_pkt_bytes < RTE_ETHER_MIN_LEN ||
> +		l2reflect_pkt_bytes > MAX_JUMBO_PKT_LEN)
> +		return -1;
> +	overhead_len = eth_dev_get_overhead_len(dev_info->max_rx_pktlen,
> +		dev_info->max_mtu);
> +	conf->rxmode.mtu = MAX(l2reflect_pkt_bytes - overhead_len,
> +			       dev_info->min_mtu);
> +	if (conf->rxmode.mtu > RTE_ETHER_MTU)
> +		conf->txmode.offloads |= RTE_ETH_TX_OFFLOAD_MULTI_SEGS;
> +	return 0;
> +}
> diff --git a/app/l2reflect/utils.h b/app/l2reflect/utils.h
> new file mode 100644
> index 0000000000..177ad8cda6
> --- /dev/null
> +++ b/app/l2reflect/utils.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2021 Siemens AG
> + */
> +
> +#ifndef _L2REFLECT_UTILS_H_
> +#define _L2REFLECT_UTILS_H_
> +
> +#define MAX_REPEAT_TIMES 30
> +#define CHECK_INTERVAL 2000
> +
> +void assert_link_status(int port_id);
> +
> +uint32_t
> +eth_dev_get_overhead_len(uint32_t max_rx_pktlen, uint16_t max_mtu);
> +
> +int
> +config_port_max_pkt_len(struct rte_eth_conf *conf,
> +			struct rte_eth_dev_info *dev_info);
> +
> +#endif /* _L2REFLECT_UTILS_H_ */
> diff --git a/app/meson.build b/app/meson.build
> index 0ea04cadeb..3593322ab2 100644
> --- a/app/meson.build
> +++ b/app/meson.build
> @@ -3,6 +3,7 @@
>   
>   apps = [
>           'dumpcap',
> +        'l2reflect',
>           'pdump',
>           'proc-info',
>           'test-acl',