--- /dev/null
+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+Interface statistics
+====================
+
+This document is a guide to Linux network interface statistics.
+
+There are two main sources of interface statistics in Linux:
+
+ - standard interface statistics based on
+ :c:type:`struct rtnl_link_stats64 <rtnl_link_stats64>`; and
+ - driver-defined statistics available via ethtool.
+
+There are multiple interfaces to reach the former. Most commonly used
+is the `ip` command from `iproute2`::
+
+ $ ip -s -s link show dev ens4u1u1
+ 6: ens4u1u1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
+ link/ether 48:2a:e3:4c:b1:d1 brd ff:ff:ff:ff:ff:ff
+ RX: bytes packets errors dropped overrun mcast
+ 74327665117 69016965 0 0 0 0
+ RX errors: length crc frame fifo missed
+ 0 0 0 0 0
+ TX: bytes packets errors dropped carrier collsns
+ 21405556176 44608960 0 0 0 0
+ TX errors: aborted fifo window heartbeat transns
+ 0 0 0 0 128
+ altname enp58s0u1u1
+
+Note that `-s` has been specified twice to see all members of
+:c:type:`struct rtnl_link_stats64 <rtnl_link_stats64>`.
+If `-s` is specified once the detailed errors won't be shown.
+
+`ip` supports JSON formatting via the `-j` option.
+
+Ethtool statistics can be dumped using `ethtool -S $ifc`, e.g.::
+
+ $ ethtool -S ens4u1u1
+ NIC statistics:
+ tx_single_collisions: 0
+ tx_multi_collisions: 0
+
+uAPIs
+=====
+
+procfs
+------
+
+The historical `/proc/net/dev` text interface gives access to the list
+of interfaces as well as their statistics.
+
+Note that even though this interface is using
+:c:type:`struct rtnl_link_stats64 <rtnl_link_stats64>`
+internally it combines some of the fields.
+
+sysfs
+-----
+
+Each device directory in sysfs contains a `statistics` directory (e.g.
+`/sys/class/net/lo/statistics/`) with files corresponding to
+members of :c:type:`struct rtnl_link_stats64 <rtnl_link_stats64>`.
+
+This simple interface is convenient especially in constrained/embedded
+environments without access to tools. However, it's inefficient when
+reading multiple stats as it internally performs a full dump of
+:c:type:`struct rtnl_link_stats64 <rtnl_link_stats64>`
+and reports only the stat corresponding to the accessed file.
+
+Sysfs files are documented in
+`Documentation/ABI/testing/sysfs-class-net-statistics`.
+
+
+netlink
+-------
+
+`rtnetlink` (`NETLINK_ROUTE`) is the preferred method of accessing
+:c:type:`struct rtnl_link_stats64 <rtnl_link_stats64>` stats.
+
+Statistics are reported both in the responses to link information
+requests (`RTM_GETLINK`) and statistic requests (`RTM_GETSTATS`,
+when `IFLA_STATS_LINK_64` bit is set in the `.filter_mask` of the request).
+
+ethtool
+-------
+
+Ethtool IOCTL interface allows drivers to report implementation
+specific statistics. Historically it has also been used to report
+statistics for which other APIs did not exist, like per-device-queue
+statistics, or standard-based statistics (e.g. RFC 2863).
+
+Statistics and their string identifiers are retrieved separately.
+Identifiers via `ETHTOOL_GSTRINGS` with `string_set` set to `ETH_SS_STATS`,
+and values via `ETHTOOL_GSTATS`. User space should use `ETHTOOL_GDRVINFO`
+to retrieve the number of statistics (`.n_stats`).
+
+debugfs
+-------
+
+Some drivers expose extra statistics via `debugfs`.
+
+struct rtnl_link_stats64
+========================
+
+.. kernel-doc:: include/uapi/linux/if_link.h
+ :identifiers: rtnl_link_stats64
+
+Notes for driver authors
+========================
+
+Drivers should report all statistics which have a matching member in
+:c:type:`struct rtnl_link_stats64 <rtnl_link_stats64>` exclusively
+via `.ndo_get_stats64`. Reporting such standard stats via ethtool
+or debugfs will not be accepted.
+
+Drivers must ensure best possible compliance with
+:c:type:`struct rtnl_link_stats64 <rtnl_link_stats64>`.
+Please note for example that detailed error statistics must be
+added into the general `rx_error` / `tx_error` counters.
+
+The `.ndo_get_stats64` callback can not sleep because of accesses
+via `/proc/net/dev`. If driver may sleep when retrieving the statistics
+from the device it should do so periodically asynchronously and only return
+a recent copy from `.ndo_get_stats64`. Ethtool interrupt coalescing interface
+allows setting the frequency of refreshing statistics, if needed.
+
+Retrieving ethtool statistics is a multi-syscall process, drivers are advised
+to keep the number of statistics constant to avoid race conditions with
+user space trying to read them.
+
+Statistics must persist across routine operations like bringing the interface
+down and up.
__u32 rx_nohandler; /* dropped, no handler found */
};
-/* The main device statistics structure */
+/**
+ * struct rtnl_link_stats64 - The main device statistics structure.
+ *
+ * @rx_packets: Number of good packets received by the interface.
+ * For hardware interfaces counts all good packets received from the device
+ * by the host, including packets which host had to drop at various stages
+ * of processing (even in the driver).
+ *
+ * @tx_packets: Number of packets successfully transmitted.
+ * For hardware interfaces counts packets which host was able to successfully
+ * hand over to the device, which does not necessarily mean that packets
+ * had been successfully transmitted out of the device, only that device
+ * acknowledged it copied them out of host memory.
+ *
+ * @rx_bytes: Number of good received bytes, corresponding to @rx_packets.
+ *
+ * For IEEE 802.3 devices should count the length of Ethernet Frames
+ * excluding the FCS.
+ *
+ * @tx_bytes: Number of good transmitted bytes, corresponding to @tx_packets.
+ *
+ * For IEEE 802.3 devices should count the length of Ethernet Frames
+ * excluding the FCS.
+ *
+ * @rx_errors: Total number of bad packets received on this network device.
+ * This counter must include events counted by @rx_length_errors,
+ * @rx_crc_errors, @rx_frame_errors and other errors not otherwise
+ * counted.
+ *
+ * @tx_errors: Total number of transmit problems.
+ * This counter must include events counter by @tx_aborted_errors,
+ * @tx_carrier_errors, @tx_fifo_errors, @tx_heartbeat_errors,
+ * @tx_window_errors and other errors not otherwise counted.
+ *
+ * @rx_dropped: Number of packets received but not processed,
+ * e.g. due to lack of resources or unsupported protocol.
+ * For hardware interfaces this counter should not include packets
+ * dropped by the device which are counted separately in
+ * @rx_missed_errors (since procfs folds those two counters together).
+ *
+ * @tx_dropped: Number of packets dropped on their way to transmission,
+ * e.g. due to lack of resources.
+ *
+ * @multicast: Multicast packets received.
+ * For hardware interfaces this statistic is commonly calculated
+ * at the device level (unlike @rx_packets) and therefore may include
+ * packets which did not reach the host.
+ *
+ * For IEEE 802.3 devices this counter may be equivalent to:
+ *
+ * - 30.3.1.1.21 aMulticastFramesReceivedOK
+ *
+ * @collisions: Number of collisions during packet transmissions.
+ *
+ * @rx_length_errors: Number of packets dropped due to invalid length.
+ * Part of aggregate "frame" errors in `/proc/net/dev`.
+ *
+ * For IEEE 802.3 devices this counter should be equivalent to a sum
+ * of the following attributes:
+ *
+ * - 30.3.1.1.23 aInRangeLengthErrors
+ * - 30.3.1.1.24 aOutOfRangeLengthField
+ * - 30.3.1.1.25 aFrameTooLongErrors
+ *
+ * @rx_over_errors: Receiver FIFO overflow event counter.
+ *
+ * Historically the count of overflow events. Such events may be
+ * reported in the receive descriptors or via interrupts, and may
+ * not correspond one-to-one with dropped packets.
+ *
+ * The recommended interpretation for high speed interfaces is -
+ * number of packets dropped because they did not fit into buffers
+ * provided by the host, e.g. packets larger than MTU or next buffer
+ * in the ring was not available for a scatter transfer.
+ *
+ * Part of aggregate "frame" errors in `/proc/net/dev`.
+ *
+ * This statistics was historically used interchangeably with
+ * @rx_fifo_errors.
+ *
+ * This statistic corresponds to hardware events and is not commonly used
+ * on software devices.
+ *
+ * @rx_crc_errors: Number of packets received with a CRC error.
+ * Part of aggregate "frame" errors in `/proc/net/dev`.
+ *
+ * For IEEE 802.3 devices this counter must be equivalent to:
+ *
+ * - 30.3.1.1.6 aFrameCheckSequenceErrors
+ *
+ * @rx_frame_errors: Receiver frame alignment errors.
+ * Part of aggregate "frame" errors in `/proc/net/dev`.
+ *
+ * For IEEE 802.3 devices this counter should be equivalent to:
+ *
+ * - 30.3.1.1.7 aAlignmentErrors
+ *
+ * @rx_fifo_errors: Receiver FIFO error counter.
+ *
+ * Historically the count of overflow events. Those events may be
+ * reported in the receive descriptors or via interrupts, and may
+ * not correspond one-to-one with dropped packets.
+ *
+ * This statistics was used interchangeably with @rx_over_errors.
+ * Not recommended for use in drivers for high speed interfaces.
+ *
+ * This statistic is used on software devices, e.g. to count software
+ * packet queue overflow (can) or sequencing errors (GRE).
+ *
+ * @rx_missed_errors: Count of packets missed by the host.
+ * Folded into the "drop" counter in `/proc/net/dev`.
+ *
+ * Counts number of packets dropped by the device due to lack
+ * of buffer space. This usually indicates that the host interface
+ * is slower than the network interface, or host is not keeping up
+ * with the receive packet rate.
+ *
+ * This statistic corresponds to hardware events and is not used
+ * on software devices.
+ *
+ * @tx_aborted_errors:
+ * Part of aggregate "carrier" errors in `/proc/net/dev`.
+ * For IEEE 802.3 devices capable of half-duplex operation this counter
+ * must be equivalent to:
+ *
+ * - 30.3.1.1.11 aFramesAbortedDueToXSColls
+ *
+ * High speed interfaces may use this counter as a general device
+ * discard counter.
+ *
+ * @tx_carrier_errors: Number of frame transmission errors due to loss
+ * of carrier during transmission.
+ * Part of aggregate "carrier" errors in `/proc/net/dev`.
+ *
+ * For IEEE 802.3 devices this counter must be equivalent to:
+ *
+ * - 30.3.1.1.13 aCarrierSenseErrors
+ *
+ * @tx_fifo_errors: Number of frame transmission errors due to device
+ * FIFO underrun / underflow. This condition occurs when the device
+ * begins transmission of a frame but is unable to deliver the
+ * entire frame to the transmitter in time for transmission.
+ * Part of aggregate "carrier" errors in `/proc/net/dev`.
+ *
+ * @tx_heartbeat_errors: Number of Heartbeat / SQE Test errors for
+ * old half-duplex Ethernet.
+ * Part of aggregate "carrier" errors in `/proc/net/dev`.
+ *
+ * For IEEE 802.3 devices possibly equivalent to:
+ *
+ * - 30.3.2.1.4 aSQETestErrors
+ *
+ * @tx_window_errors: Number of frame transmission errors due
+ * to late collisions (for Ethernet - after the first 64B of transmission).
+ * Part of aggregate "carrier" errors in `/proc/net/dev`.
+ *
+ * For IEEE 802.3 devices this counter must be equivalent to:
+ *
+ * - 30.3.1.1.10 aLateCollisions
+ *
+ * @rx_compressed: Number of correctly received compressed packets.
+ * This counters is only meaningful for interfaces which support
+ * packet compression (e.g. CSLIP, PPP).
+ *
+ * @tx_compressed: Number of transmitted compressed packets.
+ * This counters is only meaningful for interfaces which support
+ * packet compression (e.g. CSLIP, PPP).
+ *
+ * @rx_nohandler: Number of packets received on the interface
+ * but dropped by the networking stack because the device is
+ * not designated to receive packets (e.g. backup link in a bond).
+ */
struct rtnl_link_stats64 {
- __u64 rx_packets; /* total packets received */
- __u64 tx_packets; /* total packets transmitted */
- __u64 rx_bytes; /* total bytes received */
- __u64 tx_bytes; /* total bytes transmitted */
- __u64 rx_errors; /* bad packets received */
- __u64 tx_errors; /* packet transmit problems */
- __u64 rx_dropped; /* no space in linux buffers */
- __u64 tx_dropped; /* no space available in linux */
- __u64 multicast; /* multicast packets received */
+ __u64 rx_packets;
+ __u64 tx_packets;
+ __u64 rx_bytes;
+ __u64 tx_bytes;
+ __u64 rx_errors;
+ __u64 tx_errors;
+ __u64 rx_dropped;
+ __u64 tx_dropped;
+ __u64 multicast;
__u64 collisions;
/* detailed rx_errors: */
__u64 rx_length_errors;
- __u64 rx_over_errors; /* receiver ring buff overflow */
- __u64 rx_crc_errors; /* recved pkt with crc error */
- __u64 rx_frame_errors; /* recv'd frame alignment error */
- __u64 rx_fifo_errors; /* recv'r fifo overrun */
- __u64 rx_missed_errors; /* receiver missed packet */
+ __u64 rx_over_errors;
+ __u64 rx_crc_errors;
+ __u64 rx_frame_errors;
+ __u64 rx_fifo_errors;
+ __u64 rx_missed_errors;
/* detailed tx_errors */
__u64 tx_aborted_errors;
/* for cslip etc */
__u64 rx_compressed;
__u64 tx_compressed;
-
- __u64 rx_nohandler; /* dropped, no handler found */
+ __u64 rx_nohandler;
};
/* The struct should be in sync with struct ifmap */
projects / users / hch / configfs.git / commitdiff