Re: [dpdk-dev] [PATCH v4 2/2] Add l2reflect measurement application

[Henning Schild <henning.schild@siemens.com>]

Thomas,

what is the state on this one? Any more steps to take or people to
involve?

I first showed that in action back in 2016 on FOSDEM.
https://archive.fosdem.org/2016/schedule/event/virt_iaas_real_time_cloud/
After my talk two devs from dpdk approached me because they liked the
idea of a "network cyclictest". It took us some time to finally go
upstream with it, unfortunately i do not recall names.

This application can potentially be integrated into the test-suite for
QA, making sure no changes heavily increase the package transmission
worst case timing.

Sorry for not replying to the cover-letter, i was on Cc just for that
one patch of the series(s).

regards,
Henning

On Wed, 15 Jul 2020 17:54:08 +0200
Felix Moessbauer <felix.moessbauer@siemens.com> 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/Makefile              |   1 +
>  app/l2reflect/Makefile    |  14 +
>  app/l2reflect/l2reflect.h |  62 +++
>  app/l2reflect/main.c      | 872
> ++++++++++++++++++++++++++++++++++++++ app/l2reflect/meson.build |
> 25 ++ app/l2reflect/stats.c     | 205 +++++++++
>  app/l2reflect/stats.h     |  66 +++
>  app/meson.build           |   1 +
>  8 files changed, 1246 insertions(+)
>  create mode 100644 app/l2reflect/Makefile
>  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/stats.c
>  create mode 100644 app/l2reflect/stats.h
> 
> diff --git a/app/Makefile b/app/Makefile
> index 0392a7de0..43563ef0e 100644
> --- a/app/Makefile
> +++ b/app/Makefile
> @@ -7,6 +7,7 @@ DIRS-$(CONFIG_RTE_APP_TEST) += test
>  DIRS-$(CONFIG_RTE_TEST_PMD) += test-pmd
>  DIRS-$(CONFIG_RTE_PROC_INFO) += proc-info
>  DIRS-$(CONFIG_RTE_LIBRTE_PDUMP) += pdump
> +DIRS-$(CONFIG_RTE_LIBRTE_L2REFLECT) += l2reflect
>  DIRS-$(CONFIG_RTE_LIBRTE_ACL) += test-acl
>  DIRS-$(CONFIG_RTE_LIBRTE_CMDLINE) += test-cmdline
>  DIRS-$(CONFIG_RTE_LIBRTE_FIB) += test-fib
> diff --git a/app/l2reflect/Makefile b/app/l2reflect/Makefile
> new file mode 100644
> index 000000000..4e844e35d
> --- /dev/null
> +++ b/app/l2reflect/Makefile
> @@ -0,0 +1,14 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2020 Siemens AG
> +
> +include $(RTE_SDK)/mk/rte.vars.mk
> +
> +APP = l2reflect
> +
> +CFLAGS += $(WERROR_FLAGS)
> +
> +# all source are stored in SRCS-y
> +
> +SRCS-y := main.c stats.c
> +
> +include $(RTE_SDK)/mk/rte.app.mk
> diff --git a/app/l2reflect/l2reflect.h b/app/l2reflect/l2reflect.h
> new file mode 100644
> index 000000000..1d8feaf6d
> --- /dev/null
> +++ b/app/l2reflect/l2reflect.h
> @@ -0,0 +1,62 @@
> +/*
> + * SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + *
> + * authors:
> + *   Felix Moessbauer <felix.moessbauer@siemens.com>
> + *   Henning Schild <henning.schild@siemens.com>
> + */
> +#ifndef _L2REFLECT_H_
> +#define _L2REFLECT_H_
> +#define MAGIC_TRACE_PAYLOAD 0xd00faffeaffed00full
> +/* IEEE Std 802 - Local Experimental Ethertype */
> +#define ETHER_TYPE_L2REFLECT 0x88B5
> +/* Used to compare MAC addresses. */
> +#define MAC_ADDR_CMP 0xFFFFFFFFFFFFull
> +
> +enum {
> +	TRACE_TYPE_DATA,
> +	TRACE_TYPE_HELO,
> +	TRACE_TYPE_EHLO,
> +	TRACE_TYPE_RSET,
> +	TRACE_TYPE_QUIT,
> +};
> +
> +struct my_magic_packet {
> +	struct rte_ether_hdr eth;
> +	uint8_t type;
> +	uint64_t magic;
> +	uint64_t breakval;
> +};
> +
> +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 atomic_int l2reflect_output_hist;
> +extern uint64_t l2reflect_sleep_msec;
> +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;
> +
> +/*
> + * Compares a packet destination MAC address to a device MAC address.
> + */
> +static __rte_always_inline int
> +ether_addr_cmp(struct rte_ether_addr *ea, struct rte_ether_addr *eb)
> +{
> +	return ((*(uint64_t *)ea ^ *(uint64_t *)eb) & MAC_ADDR_CMP)
> == 0; +}
> +
> +#endif /* _L2REFLECT_H_ */
> diff --git a/app/l2reflect/main.c b/app/l2reflect/main.c
> new file mode 100644
> index 000000000..876cd2ea8
> --- /dev/null
> +++ b/app/l2reflect/main.c
> @@ -0,0 +1,872 @@
> +/*
> + * SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + *
> + * authors:
> + *   Felix Moessbauer <felix.moessbauer@siemens.com>
> + *   Henning Schild <henning.schild@siemens.com>
> + *
> + * 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
> + *
> + * 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.
> + */
> +
> +#include <stdio.h>
> +#include <errno.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <stdint.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 <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.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_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 "stats.h"
> +
> +#define RTE_LOGTYPE_L2REFLECT RTE_LOGTYPE_USER1
> +
> +#define NSEC_PER_SEC 1000000000
> +
> +#define MBUF_SIZE (2048 + sizeof(struct rte_mbuf) +
> RTE_PKTMBUF_HEADROOM) +#define NB_MBUF 2047
> +
> +#define MAX_PKT_BURST 32
> +/* warmup a few round before starting the measurement */
> +#define WARMUP_ROUNDS 42
> +
> +#define MAX(x, y) (((x) > (y)) ? (x) : (y))
> +#define MIN(x, y) (((x) < (y)) ? (x) : (y))
> +
> +int l2reflect_hist;
> +atomic_int l2reflect_output_hist;
> +uint64_t l2reflect_sleep_msec;
> +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,
> +	l2reflect_interrupt, trace_fd;
> +
> +static atomic_int sleep_start;
> +
> +static uint64_t rounds;
> +static int quiet, disable_int, priority, policy, l2reflect_mlock,
> +	l2reflect_interrupt, trace_fd;
> +
> +/* Configurable number of RX/TX ring descriptors */
> +#define RTE_TEST_RX_DESC_DEFAULT 128
> +#define RTE_TEST_TX_DESC_DEFAULT 512
> +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 = ETH_MQ_TX_NONE,
> +	},
> +};
> +
> +static uint32_t l2reflect_q;
> +static uint64_t l2reflect_break_usec = UINT64_MAX;
> +static uint64_t l2reflect_break_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]
> [-r] [-f] [-l]"
> +	       "[-s] [-q] [-d] [-S] [-i MSEC]\n"
> +	       "  -p PORT: port to configure\n"
> +	       "  -P PRIO: scheduling priority to use\n"
> +	       "  -b USEC: break when latency > USEC\n"
> +	       "  -r: scheduling policy SCHED_RR\n"
> +	       "  -f: scheduling policy SCHED_FIFO\n"
> +	       "  -l: lock memory (mlockall)\n"
> +	       "  -s: send one packet on startup\n"
> +	       "  -q: quiet, do not print stats\n"
> +#ifdef HAS_SYS_IO
> +	       "  -d: die die die cli\n"
> +#endif
> +	       "  -H USEC: create histogram of latencies with USEC
> time slices\n"
> +	       "  -F FILE: write histogram to file\n"
> +	       "  -S: start processing threads in sleep, wake with
> SIGUSR2\n"
> +	       "  -i MSEC: use interrupts instead of polling (cont.
> on interrupt or after MSEC)\n",
> +	       prgname);
> +}
> +
> +/* 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;
> +	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:F:i:sqdrflS", 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_CJSON
> +			printf("not compiled with cjson support\n");
> +			return -1;
> +#endif
> +			break;
> +		case 'F':
> +			hist_filename = strndup(optarg, 128);
> +			break;
> +		case 'i':
> +			l2reflect_interrupt = 1;
> +			l2reflect_sleep_msec = strtoul(optarg, NULL,
> 10);
> +			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;
> +	}
> +
> +	ret = optind - 1;
> +	optind = 0; /* reset getopt lib */
> +	return ret;
> +}
> +
> +__rte_format_printf(1, 0)
> +static void
> +trace_write(const char *fmt, ...)
> +{
> +	va_list ap;
> +	char buf[256];
> +	int n, err;
> +
> +	if (trace_fd == 0)
> +		trace_fd =
> open("/sys/kernel/debug/tracing/trace_marker",
> +				O_WRONLY);
> +	if (trace_fd < 0)
> +		return;
> +
> +	va_start(ap, fmt);
> +	n = vsnprintf(buf, 256, fmt, ap);
> +	va_end(ap);
> +
> +	err = write(trace_fd, buf, n);
> +	assert(err >= 1);
> +}
> +
> +/* Send a burst of one packet */
> +static 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;
> +
> +	ret = rte_eth_tx_burst(port, l2reflect_q, m, 1);
> +	if (unlikely(ret < 1)) {
> +		rte_pktmbuf_free(*m);
> +	} else {
> +		if (type == TRACE_TYPE_DATA) {
> +			clock_gettime(CLOCK_MONOTONIC, &last_sent);
> +			l2reflect_state = S_RUNNING;
> +		}
> +	}
> +	return 0;
> +}
> +
> +static 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->s_addr, &eth->d_addr);
> +	/* src addr */
> +	rte_ether_addr_copy(&l2reflect_port_eth_addr, &eth->s_addr);
> +
> +	if ((eth->ether_type ==
> rte_cpu_to_be_16(ETHER_TYPE_L2REFLECT)) &&
> +	    (pkt->magic == MAGIC_TRACE_PAYLOAD)) {
> +		/* and the native one */
> +		trace_write("sending traced packet\n");
> +	}
> +
> +	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;
> +
> +	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 (l2reflect_state != S_ELECT_LEADER)
> +		rte_ether_addr_copy(&l2reflect_remote_eth_addr,
> &eth->d_addr);
> +	else
> +		rte_ether_addr_copy(&ether_bcast_addr, &eth->d_addr);
> +
> +	/* src addr */
> +	rte_ether_addr_copy(&l2reflect_port_eth_addr, &eth->s_addr);
> +	eth->ether_type = rte_cpu_to_be_16(ETHER_TYPE_L2REFLECT);
> +
> +	m->data_len = 64;
> +	m->nb_segs = 1;
> +	m->pkt_len = 64;
> +	m->l2_len = sizeof(struct rte_ether_hdr);
> +
> +	pkt = (struct my_magic_packet *)eth;
> +	pkt->type = type;
> +	pkt->breakval = l2reflect_break_usec;
> +
> +	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;
> +
> +	printf("Should create a packet to play with ...\n");
> +	pnewball = l2reflect_new_pkt(TRACE_TYPE_DATA);
> +
> +	eth = rte_pktmbuf_mtod(pnewball, struct rte_ether_hdr *);
> +
> +	printf("from MAC address: %02X:%02X:%02X:%02X:%02X:%02X to"
> +			" %02X:%02X:%02X:%02X:%02X:%02X\n\n",
> +			eth->s_addr.addr_bytes[0],
> eth->s_addr.addr_bytes[1],
> +			eth->s_addr.addr_bytes[2],
> eth->s_addr.addr_bytes[3],
> +			eth->s_addr.addr_bytes[4],
> eth->s_addr.addr_bytes[5],
> +			eth->d_addr.addr_bytes[0],
> eth->d_addr.addr_bytes[1],
> +			eth->d_addr.addr_bytes[2],
> eth->d_addr.addr_bytes[3],
> +			eth->d_addr.addr_bytes[4],
> eth->d_addr.addr_bytes[5]); +
> +	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;
> +}
> +
> +static inline unsigned int
> +l2reflect_rx_filter(
> +	struct rte_mbuf **bufs,
> +	unsigned int nb_rx,
> +	unsigned int data_only)
> +{
> +	struct rte_ether_hdr *eth;
> +	struct my_magic_packet *pkt;
> +	unsigned int i, ret;
> +
> +	ret = 0;
> +	for (i = 0; i < nb_rx; i++) {
> +		eth = rte_pktmbuf_mtod(bufs[i], struct rte_ether_hdr
> *);
> +		if (l2reflect_state != S_ELECT_LEADER &&
> +		    !ether_addr_cmp(&eth->s_addr,
> &l2reflect_remote_eth_addr))
> +			goto drop;
> +
> +		if (eth->ether_type !=
> rte_cpu_to_be_16(ETHER_TYPE_L2REFLECT))
> +			goto drop;
> +
> +		pkt = (struct my_magic_packet *)eth;
> +		if (data_only && (pkt->type != TRACE_TYPE_DATA &&
> +				  pkt->type != TRACE_TYPE_RSET &&
> +				  pkt->type != TRACE_TYPE_QUIT))
> +			goto drop;
> +
> +		bufs[ret++] = bufs[i];
> +		continue;
> +drop:
> +		rte_pktmbuf_free(bufs[i]);
> +	}
> +
> +	return ret;
> +}
> +
> +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 my_magic_packet *pkt;
> +	uint64_t my_mac, other_mac, breakval;
> +	unsigned int i, nb_rx;
> +	int i_win;
> +	int searching = 1;
> +
> +	other_mac = 0ULL;
> +	my_mac = 0ULL;
> +	breakval = 0;
> +
> +	while (l2reflect_state == S_ELECT_LEADER) {
> +		nb_rx = rte_eth_rx_burst(portid, l2reflect_q,
> pkts_burst,
> +					 MAX_PKT_BURST);
> +		nb_rx = l2reflect_rx_filter(pkts_burst, nb_rx, 0);
> +		for (i = 0; i < nb_rx && searching; i++) {
> +			eth = rte_pktmbuf_mtod(pkts_burst[i],
> +					       struct rte_ether_hdr
> *);
> +			pkt = (struct my_magic_packet *)eth;
> +			if (pkt->type == TRACE_TYPE_HELO ||
> +			    pkt->type == TRACE_TYPE_EHLO) {
> +				l2reflect_state = S_RUNNING;
> +				rte_ether_addr_copy(&eth->s_addr,
> +
> &l2reflect_remote_eth_addr);
> +				rte_ether_addr_copy(
> +					&eth->s_addr,
> +					(struct rte_ether_addr
> *)&other_mac);
> +				rte_ether_addr_copy(
> +					&l2reflect_port_eth_addr,
> +					(struct rte_ether_addr
> *)&my_mac);
> +				breakval = pkt->breakval;
> +				/* break, but cleanup */
> +				searching = 0;
> +			}
> +			if (pkt->type == TRACE_TYPE_HELO) {
> +				m =
> l2reflect_new_pkt(TRACE_TYPE_EHLO);
> +				RTE_LOG(INFO, L2REFLECT, "found one
> EHLO\n");
> +				l2reflect_send_packet(&m,
> +
> l2reflect_port_number);
> +			}
> +			rte_pktmbuf_free(pkts_burst[i]);
> +		}
> +		m = l2reflect_new_pkt(TRACE_TYPE_HELO);
> +		RTE_LOG(INFO, L2REFLECT, "looking for player
> HELO\n");
> +		l2reflect_send_packet(&m, l2reflect_port_number);
> +		usleep(500000);
> +	}
> +	/* leave election logic */
> +	if (l2reflect_state != S_RUNNING)
> +		return 0;
> +
> +	if (my_mac == other_mac)
> +		rte_exit(EXIT_FAILURE, "talking to myself ...
> confused\n"); +
> +	/* the one with the bigger MAC is the leader */
> +	i_win = (my_mac > other_mac);
> +
> +	RTE_LOG(INFO, L2REFLECT, "i am the \"%s\"\n", i_win ? "rick"
> : "morty"); +
> +	/* looser takes tracing break value from winner */
> +	if (!i_win)
> +		l2reflect_break_usec = breakval;
> +
> +	return i_win;
> +}
> +
> +/*
> + * add the measured time diff to the statistics.
> + * return false if threshold is hit
> + */
> +static inline bool
> +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) {
> +		if (l2reflect_hist) {
> +			const uint64_t bucket =
> +				MIN(diff / (hist_bucket_usec * 1000),
> +				    HIST_CAP_BUCKET);
> +			record.hist[bucket]++;
> +		}
> +
> +		record.avg_round += (double)diff;
> +		if (diff < record.min_round)
> +			record.min_round = diff;
> +		if (diff > record.max_round) {
> +			record.max_round = diff;
> +			if (l2reflect_break_usec &&
> +				(record.max_round >
> +					l2reflect_break_usec *
> +						1000))
> +				return false;
> +		}
> +	}
> +	return true;
> +}
> +
> +/*
> + * process a single packet.
> + * return false if latency threshold is hit
> + */
> +static inline bool
> +process_packet(
> +	struct my_magic_packet *pkt,
> +	uint64_t *diff)
> +{
> +	if (pkt->type == TRACE_TYPE_DATA) {
> +		clock_gettime(CLOCK_MONOTONIC, &last_recv);
> +		*diff = calcdiff_ns(last_recv, last_sent);
> +		if (!add_to_record(*diff))
> +			return false;
> +	}
> +	if (pkt->magic == MAGIC_TRACE_PAYLOAD) {
> +		/* and the native one */
> +		trace_write("received traced packet\n");
> +	}
> +	return true;
> +}
> +
> +/* 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;
> +	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);
> +
> +restart:
> +	init_record();
> +	l2reflect_state = S_ELECT_LEADER;
> +	sender = elect_leader(portid);
> +
> +	/* we are the sender so we bring one ball into the game */
> +	if (sender)
> +		l2reflect_new_ball();
> +
> +	while (l2reflect_state == S_RUNNING) {
> +		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);
> +
> +		/* TODO use drivers/hw to filter mac */
> +		nb_rx = l2reflect_rx_filter(pkts_burst, nb_rx, 1);
> +
> +		/* remote is telling us to reset or stop */
> +		if (nb_rx) {
> +			eth = rte_pktmbuf_mtod(pkts_burst[0],
> +					       struct rte_ether_hdr
> *);
> +			pkt = (struct my_magic_packet *)eth;
> +			if (eth->ether_type ==
> +
> rte_cpu_to_be_16(ETHER_TYPE_L2REFLECT)) {
> +				if (pkt->type == TRACE_TYPE_RSET) {
> +
> rte_pktmbuf_free(pkts_burst[0]);
> +					goto restart;
> +				}
> +				if (pkt->type == TRACE_TYPE_QUIT) {
> +					l2reflect_state =
> S_REMOTE_TERM;
> +					break;
> +				}
> +			}
> +		}
> +
> +		if (l2reflect_state == S_RUNNING && nb_rx) {
> +			eth = rte_pktmbuf_mtod(pkts_burst[0],
> +					struct rte_ether_hdr *);
> +			pkt = (struct my_magic_packet *)eth;
> +			if (eth->ether_type ==
> +
> rte_cpu_to_be_16(ETHER_TYPE_L2REFLECT)) {
> +				if (!process_packet(pkt, &diff))
> +					break;
> +			}
> +		}
> +		for (j = 0; j < nb_rx; j++) {
> +			m = pkts_burst[j];
> +			rte_prefetch0(rte_pktmbuf_mtod(m, void *));
> +			l2reflect_simple_forward(m);
> +		}
> +	}
> +	const int state_cpy = l2reflect_state;
> +	switch (state_cpy) {
> +	case S_RESET_TRX:
> +		l2reflect_send_reset();
> +		l2reflect_state = S_ELECT_LEADER;
> +	case S_ELECT_LEADER:
> +		goto restart;
> +	}
> +
> +	if (state_cpy == S_LOCAL_TERM) {
> +		l2reflect_send_quit();
> +		if (record.max_round > l2reflect_break_usec) {
> +			printf("hit latency threshold (%" PRIu64
> +			       ".%03u > %" PRIu64 ")\n",
> +			       diff / 1000, (unsigned int)(diff %
> 1000),
> +			       l2reflect_break_usec);
> +		}
> +	} else if (state_cpy == S_REMOTE_TERM) {
> +		printf("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) {
> +		printf("Sleeping and waiting for SIGCONT\n");
> +		while (sleep_start)
> +			usleep(10000);
> +
> +		printf("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;
> +	int ret;
> +	uint32_t i;
> +	uint16_t nb_ports;
> +	unsigned int lcore_id;
> +	struct sigaction action;
> +	bzero(&action, sizeof(action));
> +	char mempool_name[128];
> +
> +	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();
> +	/* 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());
> +	printf("About to create mempool \"%s\"\n", mempool_name);
> +	/* create the mbuf pool */
> +	l2reflect_pktmbuf_pool =
> +		rte_mempool_create(mempool_name, NB_MBUF, MBUF_SIZE,
> +			MAX_PKT_BURST, sizeof(struct
> rte_pktmbuf_pool_private),
> +			rte_pktmbuf_pool_init, NULL,
> +			rte_pktmbuf_init, NULL, rte_socket_id(), 0);
> +
> +	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);
> +	printf("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);
> +	printf("Initializing port %u... ", l2reflect_port_number);
> +	fflush(stdout);
> +
> +	if (l2reflect_interrupt)
> +		port_conf.intr_conf.rxq = 1;
> +	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);
> +
> +	rte_eth_macaddr_get(l2reflect_port_number,
> &l2reflect_port_eth_addr); +
> +	/* init RX queues */
> +	fflush(stdout);
> +	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 */
> +	fflush(stdout);
> +	ret = rte_eth_tx_queue_setup(
> +		l2reflect_port_number, 0, nb_txd,
> +		rte_eth_dev_socket_id(l2reflect_port_number), NULL);
> +	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_promiscuous_enable(l2reflect_port_number);
> +
> +	printf("Port %u, MAC address:
> %02X:%02X:%02X:%02X:%02X:%02X\n\n",
> +	       (unsigned int)l2reflect_port_number,
> +	       l2reflect_port_eth_addr.addr_bytes[0],
> +	       l2reflect_port_eth_addr.addr_bytes[1],
> +	       l2reflect_port_eth_addr.addr_bytes[2],
> +	       l2reflect_port_eth_addr.addr_bytes[3],
> +	       l2reflect_port_eth_addr.addr_bytes[4],
> +	       l2reflect_port_eth_addr.addr_bytes[5]);
> +
> +	/*
> +	 * in quiet mode the master executes the main packet loop
> +	 * otherwise the one slave does it and the master prints
> stats
> +	 */
> +	if (quiet) {
> +		assert(rte_lcore_count() == 1);
> +#ifdef HAS_SYS_IO
> +		if (disable_int) {
> +			iopl(3);
> +			asm("cli");
> +		}
> +#endif
> +		l2reflect_launch_one_lcore(NULL);
> +	} else {
> +		assert(rte_lcore_count() == 2);
> +		/* the slave reflects the packets */
> +		RTE_LCORE_FOREACH_SLAVE(lcore_id)
> +		{
> +
> rte_eal_remote_launch(l2reflect_launch_one_lcore, NULL,
> +					      lcore_id);
> +		}
> +
> +		/* the master prints the stats */
> +		init_record();
> +		l2reflect_stats_loop();
> +		rte_eal_mp_wait_lcore();
> +	}
> +	rte_eal_cleanup();
> +
> +	if (l2reflect_hist)
> +		output_histogram_snapshot();
> +
> +	cleanup_record();
> +
> +	if (trace_fd)
> +		close(trace_fd);
> +
> +	return 0;
> +}
> diff --git a/app/l2reflect/meson.build b/app/l2reflect/meson.build
> new file mode 100644
> index 000000000..d9dd27ed7
> --- /dev/null
> +++ b/app/l2reflect/meson.build
> @@ -0,0 +1,25 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2020 Siemens AG
> +
> +# meson file, for building this example as part of a main DPDK build.
> +cc = meson.get_compiler('c')
> +
> +cjson = dependency('libcjson', required: false)
> +
> +if not cjson.found()
> +    cjson = cc.find_library('cjson', required: false)
> +endif
> +
> +if not is_linux
> +        build = false
> +endif
> +if cc.has_header('sys/io.h')
> +    cflags += '-DHAS_SYS_IO'
> +endif
> +
> +sources = files('main.c', 'stats.c')
> +deps += ['ethdev']
> +if cjson.found()
> +    ext_deps += cjson
> +    cflags += '-DRTE_HAS_CJSON'
> +endif
> diff --git a/app/l2reflect/stats.c b/app/l2reflect/stats.c
> new file mode 100644
> index 000000000..f3759bc4f
> --- /dev/null
> +++ b/app/l2reflect/stats.c
> @@ -0,0 +1,205 @@
> +/*
> + * SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + *
> + * authors:
> + *   Felix Moessbauer <felix.moessbauer@siemens.com>
> + *   Henning Schild <henning.schild@siemens.com>
> + */
> +#include <stdio.h>
> +#include <sys/types.h>
> +#include <unistd.h>
> +#include <string.h>
> +#ifdef RTE_HAS_CJSON
> +#include <cjson/cJSON.h>
> +#endif
> +#include "stats.h"
> +
> +#define ANSI_BOLD_RED "\x1b[01;31m"
> +#define ANSI_BOLD_GREEN "\x1b[01;32m"
> +#define ANSI_BOLD_YELLOW "\x1b[01;33m"
> +#define ANSI_BOLD_BLUE "\x1b[01;34m"
> +#define ANSI_BOLD_MAGENTA "\x1b[01;35m"
> +#define ANSI_BOLD_CYAN "\x1b[01;36m"
> +#define ANSI_RESET "\x1b[0m"
> +
> +unsigned int hist_bucket_usec;
> +struct stats record;
> +char *hist_filename;
> +
> +void
> +init_record(void)
> +{
> +	record.max_round = 0;
> +	record.min_round = MIN_INITIAL;
> +	record.rounds = 0;
> +	record.timeouts = 0;
> +	record.avg_round = 0;
> +	if (l2reflect_hist) {
> +		if (!record.hist_size) {
> +			record.hist =
> +				calloc(HIST_NUM_BUCKETS,
> sizeof(uint64_t));
> +			record.hist_size = HIST_NUM_BUCKETS;
> +		} else {
> +			memset(record.hist, 0,
> +			       record.hist_size * sizeof(uint64_t));
> +		}
> +	}
> +}
> +
> +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 = stdout;
> +	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;
> +
> +	rte_eth_stats_get(l2reflect_port_number, &stats);
> +
> +	/* Clear screen and move to top left */
> +	printf("%s%s", clr, topLeft);
> +
> +	printf(ANSI_BOLD_GREEN "Networking Roundtrip Test\n"
> +			ANSI_RESET);
> +	printf(ANSI_BOLD_MAGENTA
> +			"\nPort statistics
> ===================================="
> +			ANSI_RESET);
> +
> +	printf("\nMe: %02X:%02X:%02X:%02X:%02X:%02X <--> "
> +			"Remote: %02X:%02X:%02X:%02X:%02X:%02X",
> +			l2reflect_port_eth_addr.addr_bytes[0],
> +			l2reflect_port_eth_addr.addr_bytes[1],
> +			l2reflect_port_eth_addr.addr_bytes[2],
> +			l2reflect_port_eth_addr.addr_bytes[3],
> +			l2reflect_port_eth_addr.addr_bytes[4],
> +			l2reflect_port_eth_addr.addr_bytes[5],
> +			l2reflect_remote_eth_addr.addr_bytes[0],
> +			l2reflect_remote_eth_addr.addr_bytes[1],
> +			l2reflect_remote_eth_addr.addr_bytes[2],
> +			l2reflect_remote_eth_addr.addr_bytes[3],
> +			l2reflect_remote_eth_addr.addr_bytes[4],
> +			l2reflect_remote_eth_addr.addr_bytes[5]);
> +	printf("\nStatistics for port %d PID %d on lcore %d
> ---------"
> +			"\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 "    (>%9"
> PRIu64 "ms)",
> +			l2reflect_port_number, getpid(),
> rte_lcore_id(),
> +			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,
> l2reflect_sleep_msec);
> +	printf(ANSI_BOLD_MAGENTA
> +			"\nPort timing statistics
> ============================="
> +			ANSI_RESET);
> +	if (l2reflect_state == S_ELECT_LEADER ||
> +		record.min_round == MIN_INITIAL) {
> +		printf("\n\nBenchmark not started yet...\n");
> +	} else {
> +		printf("\n" ANSI_BOLD_RED "Max" ANSI_RESET
> +				" roundtrip: %19" PRIu64 " us",
> +				record.max_round / 1000);
> +		printf("\n" ANSI_BOLD_YELLOW "Avg" ANSI_RESET
> +				" roundtrip: %19" PRIu64 " us",
> +				record.rounds ?
> (uint64_t)(record.avg_round /
> +				record.rounds / 1000) :
> +				0);
> +		printf("\n" ANSI_BOLD_GREEN "Min" ANSI_RESET
> +				" roundtrip: %19" PRIu64 " us",
> +				record.min_round / 1000);
> +	}
> +	printf(ANSI_BOLD_MAGENTA
> +
> "\n===================================================="
> +			ANSI_RESET "\n");
> +}
> +
> +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;
> +		}
> +		sleep(1);
> +	}
> +}
> +
> +char *
> +serialize_histogram(__rte_unused const struct stats *record)
> +{
> +#ifndef RTE_HAS_CJSON
> +	return strdup("to print histogram, build with cjson
> support"); +#else
> +	char *str = NULL;
> +	char key[8];
> +	unsigned int i;
> +	cJSON *hist0, *cpu0, *all_cpus, *output;
> +
> +	output = cJSON_CreateObject();
> +	/* version: 1 */
> +	cJSON_AddItemToObject(output, "version",
> cJSON_CreateNumber(1)); +
> +	/* cpu 0 histogram */
> +	hist0 = cJSON_CreateObject();
> +	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);
> +			cJSON_AddNumberToObject(hist0, key,
> record->hist[i]);
> +		}
> +	}
> +
> +	/* cpu 0 stats */
> +	cpu0 = cJSON_CreateObject();
> +	cJSON_AddItemToObject(cpu0, "histogram", hist0);
> +	cJSON_AddItemToObject(cpu0, "count",
> +
> cJSON_CreateNumber(record->rounds));
> +	cJSON_AddItemToObject(cpu0, "min",
> +
> cJSON_CreateNumber(record->min_round));
> +	cJSON_AddItemToObject(cpu0, "max",
> +
> cJSON_CreateNumber(record->max_round));
> +	cJSON_AddItemToObject(cpu0, "avg",
> +
> cJSON_CreateNumber((record->avg_round /
> +						record->rounds /
> 1000))); +
> +	/* combine objects */
> +	all_cpus = cJSON_CreateObject();
> +	cJSON_AddItemToObject(all_cpus, "0", cpu0);
> +	cJSON_AddItemToObject(output, "cpu", all_cpus);
> +
> +	str = cJSON_Print(output);
> +
> +	/* cleanup */
> +	cJSON_Delete(output);
> +
> +	return str;
> +#endif
> +}
> diff --git a/app/l2reflect/stats.h b/app/l2reflect/stats.h
> new file mode 100644
> index 000000000..a7d31bbc5
> --- /dev/null
> +++ b/app/l2reflect/stats.h
> @@ -0,0 +1,66 @@
> +/*
> + * SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Siemens AG
> + *
> + * authors:
> + *   Felix Moessbauer <felix.moessbauer@siemens.com>
> + *   Henning Schild <henning.schild@siemens.com>
> + */
> +#ifndef _STATS_H_
> +#define _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 128
> +#define HIST_CAP_BUCKET (HIST_NUM_BUCKETS - 1)
> +
> +/* runtime statistics */
> +struct stats {
> +	uint64_t max_round;
> +	uint64_t min_round;
> +	uint64_t rounds;
> +	uint64_t timeouts;
> +	double avg_round;
> +	unsigned int hist_size;
> +	/* each slot is 10us */
> +	uint64_t *hist;
> +};
> +
> +/* 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);
> +
> +#endif /* _STATS_H_ */
> diff --git a/app/meson.build b/app/meson.build
> index a29eba024..3dfdbb58c 100644
> --- a/app/meson.build
> +++ b/app/meson.build
> @@ -8,6 +8,7 @@ endif
>  apps = [
>  	'pdump',
>  	'proc-info',
> +	'l2reflect',
>  	'test-acl',
>  	'test-bbdev',
>  	'test-cmdline',