From 78227847a6c17d890b405b057fc87e651de31604 Mon Sep 17 00:00:00 2001 From: Remi Gacogne Date: Fri, 27 Apr 2018 18:49:33 +0200 Subject: [PATCH] rec: Clarify a bit what an incomning UDP queries processing round is --- pdns/pdns_recursor.cc | 2 +- pdns/recursordist/docs/settings.rst | 7 +++++-- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/pdns/pdns_recursor.cc b/pdns/pdns_recursor.cc index 4cb9df415..159680227 100644 --- a/pdns/pdns_recursor.cc +++ b/pdns/pdns_recursor.cc @@ -3646,7 +3646,7 @@ int main(int argc, char **argv) ::arg().set("max-qperq", "Maximum outgoing queries per query")="50"; ::arg().set("max-total-msec", "Maximum total wall-clock time per query in milliseconds, 0 for unlimited")="7000"; ::arg().set("max-recursion-depth", "Maximum number of internal recursion calls per query, 0 for unlimited")="40"; - ::arg().set("max-udp-queries-per-round", "Maximum number of UDP queries processed per round, before returning back to normal processing")="10000"; + ::arg().set("max-udp-queries-per-round", "Maximum number of UDP queries processed per recvmsg() round, before returning back to normal processing")="10000"; ::arg().set("include-dir","Include *.conf files from this directory")=""; ::arg().set("security-poll-suffix","Domain name from which to query security update notifications")="secpoll.powerdns.com."; diff --git a/pdns/recursordist/docs/settings.rst b/pdns/recursordist/docs/settings.rst index 8e2004e59..9432d3b50 100644 --- a/pdns/recursordist/docs/settings.rst +++ b/pdns/recursordist/docs/settings.rst @@ -777,8 +777,11 @@ Total maximum number of milliseconds of wallclock time the server may use to ans - Integer - Default: 10000 -Maximum number of DNS queries processed in a single round after being woken up by the multiplexer, before -returning back to normal processing to handle other events. +Under heavy load the recursor might be busy processing incoming UDP queries for a long while before there is no more of these, and might therefore +neglect scheduling new ``mthreads``, handling responses from authoritative servers or responding to :doc:`rec_control ` +requests. +This setting caps the maximum number of incoming UDP DNS queries processed in a single round of looping on ``recvmsg()`` after being woken up by the multiplexer, before +returning back to normal processing and handling other events. .. _setting-minimum-ttl-override: -- 2.40.0