From cda8e7ba218e391fdd2459d3fefdbc86db118ce0 Mon Sep 17 00:00:00 2001 From: ClaudioRifo Date: Fri, 29 Apr 2022 18:18:17 -0400 Subject: [PATCH] Update statistics.rst Notes that help understand some UDP counters. Note that help understand that counters from /proc/net/ are global and O.S. related. --- pdns/dnsdistdist/docs/statistics.rst | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/pdns/dnsdistdist/docs/statistics.rst b/pdns/dnsdistdist/docs/statistics.rst index e8d5ba5797..648ef07efa 100644 --- a/pdns/dnsdistdist/docs/statistics.rst +++ b/pdns/dnsdistdist/docs/statistics.rst @@ -21,6 +21,8 @@ Note that packets dropped by eBPF (see :doc:`../advanced/ebpf`) are accounted for in the eBPF statistics, and do not show up in the metrics described on this page. +Note that counters that come from /proc/net/ are O.S. Counters. They do not reset on service restart and they are not only related to DNSDist. + acl-drops --------- The number of packets (or TCP messages) dropped because of the :doc:`ACL `. @@ -312,30 +314,35 @@ udp-in-errors .. versionadded:: 1.5.0 From /proc/net/snmp InErrors. +Incremented in several cases: no memory in the receive queue, when a bad checksum is seen, and if sk_add_backlog fails to add the datagram. udp-noport-errors ----------------- .. versionadded:: 1.5.0 From /proc/net/snmp NoPorts. +Incremented when UDP packets arrive destined for a port where no program is listening. udp-recvbuf-errors ------------------ .. versionadded:: 1.5.0 From /proc/net/snmp RcvbufErrors. +Incremented when sock_queue_rcv_skb reports that no memory is available; this happens if sk->sk_rmem_alloc is greater than or equal to sk->sk_rcvbuf. udp-sndbuf-errors ----------------- .. versionadded:: 1.5.0 From /proc/net/snmp SndbufErrors. +Incremented if the IP protocol layer reported an error when trying to send the packet and no error queue has been setup. Also incremented if no send queue space or kernel memory are available. udp6-in-csum-errors ------------------- .. versionadded:: 1.7.0 From /proc/net/snmp6 InErrors. +Incremented when a UDP checksum failure is detected. Note that in all cases I could find, InCsumErrors is incremented at the same time as InErrors. Thus, InErrors - InCsumErros should yield the count of memory related errors on the receive side. udp6-in-errors -------------- -- 2.47.2