[PATCH v5 04/10] net/rtap: add statistics and device info

Stephen Hemminger
2026-02-09T18:41:21Z

Implement basic and per-queue statistics collection and the device
info query.

Stats tracked per rx queue: packets, bytes, errors, and missed.
Stats tracked per tx queue: packets, bytes, errors.

Device info reports:
- Interface index from the kernel TAP device
- Maximum queue counts
- Default burst size and ring size

Enable AUTOFILL_QUEUE_XSTATS for automatic per-queue extended
statistics.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
doc/guides/nics/features/rtap.ini | 2 +
drivers/net/rtap/rtap.h | 2 +
drivers/net/rtap/rtap_ethdev.c | 139 ++++++++++++++++++++++++++++++
3 files changed, 143 insertions(+)

diff --git a/doc/guides/nics/features/rtap.ini b/doc/guides/nics/features/rtap.ini
index c064e1e0b9..9bef9e341d 100644
--- a/doc/guides/nics/features/rtap.ini
+++ b/doc/guides/nics/features/rtap.ini
@@ -5,6 +5,8 @@
;
[Features]
Scattered Rx = P
+Basic stats = Y
+Stats per queue = Y
Linux = Y
ARMv7 = Y
ARMv8 = Y
diff --git a/drivers/net/rtap/rtap.h b/drivers/net/rtap/rtap.h
index a0bbb1a8a0..a93d7dae17 100644
--- a/drivers/net/rtap/rtap.h
+++ b/drivers/net/rtap/rtap.h
@@ -64,6 +64,8 @@ struct rtap_pmd {
int keep_fd; /* keep alive file descriptor */
char ifname[IFNAMSIZ]; /* name assigned by kernel */
struct rte_ether_addr eth_addr; /* address assigned by kernel */
+
+ uint64_t rx_drop_base; /* value of rx_dropped when reset */
};

/* rtap_ethdev.c */
diff --git a/drivers/net/rtap/rtap_ethdev.c b/drivers/net/rtap/rtap_ethdev.c
index a65a8b77ad..a8481d9864 100644
--- a/drivers/net/rtap/rtap_ethdev.c
+++ b/drivers/net/rtap/rtap_ethdev.c
@@ -7,6 +7,7 @@
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
+#include <inttypes.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/if.h>
@@ -30,6 +31,14 @@

#define RTAP_DEFAULT_IFNAME "rtap%d"

+#define RTAP_DEFAULT_BURST 64
+#define RTAP_NUM_BUFFERS 1024
+#define RTAP_MAX_QUEUES 128
+#define RTAP_MIN_RX_BUFSIZE RTE_ETHER_MIN_LEN
+#define RTAP_MAX_RX_PKTLEN RTE_ETHER_MAX_JUMBO_FRAME_LEN
+
+static_assert(RTAP_MAX_QUEUES <= RTE_MP_MAX_FD_NUM, "Max queues exceeds MP fd limit");
+
#define RTAP_IFACE_ARG "iface"
#define RTAP_PERSIST_ARG "persist"

@@ -153,6 +162,132 @@ rtap_dev_configure(struct rte_eth_dev *dev)
return 0;
}

+static int
+rtap_dev_info(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
+{
+ struct rtap_pmd *pmd = dev->data->dev_private;
+
+ dev_info->if_index = if_nametoindex(pmd->ifname);
+ dev_info->max_mac_addrs = 1;
+ dev_info->max_rx_pktlen = RTAP_MAX_RX_PKTLEN;
+ dev_info->min_rx_bufsize = RTAP_MIN_RX_BUFSIZE;
+ dev_info->max_rx_queues = RTAP_MAX_QUEUES;
+ dev_info->max_tx_queues = RTAP_MAX_QUEUES;
+
+ dev_info->default_rxportconf = (struct rte_eth_dev_portconf) {
+ .burst_size = RTAP_DEFAULT_BURST,
+ .ring_size = RTAP_NUM_BUFFERS,
+ .nb_queues = 1,
+ };
+ dev_info->default_txportconf = (struct rte_eth_dev_portconf) {
+ .burst_size = RTAP_DEFAULT_BURST,
+ .ring_size = RTAP_NUM_BUFFERS,
+ .nb_queues = 1,
+ };
+ return 0;
+}
+
+/* Use sysfs to ask kernel what packets were dropped before making it to interface */
+static int
+rtap_get_rx_dropped(const char *ifname, uint64_t *rx_dropped)
+{
+ char path[256];
+
+ snprintf(path, sizeof(path), "/sys/class/net/%s/statistics/rx_dropped",
+ ifname);
+
+ FILE *f = fopen(path, "r");
+ if (f == NULL) {
+ PMD_LOG_ERRNO(NOTICE, "open %s failed", path);
+ return -errno;
+ }
+
+ if (fscanf(f, "%"SCNu64, rx_dropped) != 1) {
+ PMD_LOG(NOTICE, "parse of rx_dropped failed");
+ fclose(f);
+ return -EIO;
+ }
+
+ fclose(f);
+ return 0;
+}
+
+static int
+rtap_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats,
+ struct eth_queue_stats *qstats)
+{
+ struct rtap_pmd *pmd = dev->data->dev_private;
+ uint16_t i;
+
+ for (i = 0; i < dev->data->nb_rx_queues; i++) {
+ struct rtap_rx_queue *rxq = dev->data->rx_queues[i];
+ if (rxq == NULL)
+ continue;
+
+ stats->ipackets += rxq->rx_packets;
+ stats->ibytes += rxq->rx_bytes;
+ stats->ierrors += rxq->rx_errors;
+
+ if (qstats != NULL && i < RTE_ETHDEV_QUEUE_STAT_CNTRS) {
+ qstats->q_ipackets[i] = rxq->rx_packets;
+ qstats->q_ibytes[i] = rxq->rx_bytes;
+ qstats->q_errors[i] = rxq->rx_errors;
+ }
+ }
+
+ for (i = 0; i < dev->data->nb_tx_queues; i++) {
+ struct rtap_tx_queue *txq = dev->data->tx_queues[i];
+ if (txq == NULL)
+ continue;
+
+ stats->opackets += txq->tx_packets;
+ stats->obytes += txq->tx_bytes;
+ stats->oerrors += txq->tx_errors;
+
+ if (qstats != NULL && i < RTE_ETHDEV_QUEUE_STAT_CNTRS) {
+ qstats->q_opackets[i] = txq->tx_packets;
+ qstats->q_obytes[i] = txq->tx_bytes;
+ }
+ }
+
+ uint64_t rx_dropped = 0;
+ if (rtap_get_rx_dropped(pmd->ifname, &rx_dropped) == 0 &&
+ rx_dropped > pmd->rx_drop_base)
+ stats->imissed = rx_dropped - pmd->rx_drop_base;
+
+ return 0;
+}
+
+static int
+rtap_stats_reset(struct rte_eth_dev *dev)
+{
+ struct rtap_pmd *pmd = dev->data->dev_private;
+ uint16_t i;
+
+ for (i = 0; i < dev->data->nb_rx_queues; i++) {
+ struct rtap_rx_queue *rxq = dev->data->rx_queues[i];
+ if (rxq == NULL)
+ continue;
+
+ rxq->rx_packets = 0;
+ rxq->rx_bytes = 0;
+ rxq->rx_errors = 0;
+ }
+
+ for (i = 0; i < dev->data->nb_tx_queues; i++) {
+ struct rtap_tx_queue *txq = dev->data->tx_queues[i];
+ if (txq == NULL)
+ continue;
+
+ txq->tx_packets = 0;
+ txq->tx_bytes = 0;
+ txq->tx_errors = 0;
+ }
+
+ rtap_get_rx_dropped(pmd->ifname, &pmd->rx_drop_base);
+ return 0;
+}
+
static int
rtap_dev_close(struct rte_eth_dev *dev)
{
@@ -231,7 +366,10 @@ static const struct eth_dev_ops rtap_ops = {
.dev_start = rtap_dev_start,
.dev_stop = rtap_dev_stop,
.dev_configure = rtap_dev_configure,
+ .dev_infos_get = rtap_dev_info,
.dev_close = rtap_dev_close,
+ .stats_get = rtap_stats_get,
+ .stats_reset = rtap_stats_reset,
.rx_queue_setup = rtap_rx_queue_setup,
.rx_queue_release = rtap_rx_queue_release,
.tx_queue_setup = rtap_tx_queue_setup,
@@ -245,6 +383,7 @@ rtap_create(struct rte_eth_dev *dev, const char *tap_name, uint8_t persist)
struct rtap_pmd *pmd = data->dev_private;

pmd->keep_fd = -1;
+ pmd->rx_drop_base = 0;

dev->dev_ops = &rtap_ops;

--
2.51.0