Change defaults to pdns-distributes-queries = no and reuseport = yes

diff --git a/pdns/recursordist/docs/settings.rst b/pdns/recursordist/docs/settings.rst
index ec4c60e65faa7100d05c067a1b48b868df705be8..ba22422f980ee598590ebc6724ec999c89b3a2ce 100644 (file)
--- a/pdns/recursordist/docs/settings.rst
+++ b/pdns/recursordist/docs/settings.rst
@@ -466,8 +466,7 @@ overloaded, but it will be at the cost of an increased latency.
 -  Default: 1 if `pdns-distributes-queries`_ is set, 0 otherwise
 
 If `pdns-distributes-queries`_ is set, spawn this number of distributor threads on startup. Distributor threads
-handle incoming queries and distribute them to other threads based on a hash of the query, to maximize the cache hit
-ratio.
+handle incoming queries and distribute them to other threads based on a hash of the query.
 
 .. _setting-dot-to-auth-names:
 
@@ -1636,12 +1635,17 @@ you can try to enlarge this value or run with fewer threads.
 ``pdns-distributes-queries``
 ----------------------------
 -  Boolean
--  Default: yes
+-  Default: no
 
 If set, PowerDNS will use distinct threads to listen to client sockets and distribute that work to worker-threads using a hash of the query.
-This feature should maximize the cache hit ratio.
-To use more than one thread set `distributor-threads` in version 4.2.0 or newer.
-Enabling should improve performance for medium sized resolvers.
+This feature should maximize the cache hit ratio on versions before 4.9.0.
+To use more than one thread set `distributor-threads`_ in version 4.2.0 or newer.
+Enabling should improve performance on systems where `reuseport`_ does not have the effect of
+balancing the queries evenly over multiple worker threads.
+
+.. versionchanged:: 4.9.0
+
+   Default changed to ``no``, previously it was ``yes``.
 
 .. _setting-protobuf-use-kernel-timestamp:
 
@@ -1801,11 +1805,16 @@ A typical value is 10. If the value is zero, this functionality is disabled.
 ``reuseport``
 -------------
 -  Boolean
--  Default: no
+-  Default: yes
 
 If ``SO_REUSEPORT`` support is available, allows multiple threads and processes to open listening sockets for the same port.
 
-Since 4.1.0, when ``pdns-distributes-queries`` is set to false and ``reuseport`` is enabled, every worker-thread will open a separate listening socket to let the kernel distribute the incoming queries instead of running a distributor thread (which could otherwise be a bottleneck) and avoiding thundering herd issues, thus leading to much higher performance on multi-core boxes.
+Since 4.1.0, when `pdns-distributes-queries`_ is disabled and `reuseport`_ is enabled, every worker-thread will open a separate listening socket to let the kernel distribute the incoming queries instead of running a distributor thread (which could otherwise be a bottleneck) and avoiding thundering herd issues, thus leading to much higher performance on multi-core boxes.
+
+.. versionchanged:: 4.9.0
+
+   The default is changed to ``yes``, previously it was ``no``.
+   If ``SO_REUSEPORT`` support is not available, the setting defaults to ``no``.
 
 .. _setting-rng:
 

diff --git a/pdns/recursordist/rec-main.cc b/pdns/recursordist/rec-main.cc
index 52dfa60d22175ae3979f7c2294f577b5385cf5e5..7de44b7187ca14f50a3a4a97a3215c8ca5fce972 100644 (file)
--- a/pdns/recursordist/rec-main.cc
+++ b/pdns/recursordist/rec-main.cc
@@ -2739,7 +2739,7 @@ int main(int argc, char** argv)
     ::arg().set("ecs-add-for", "List of client netmasks for which EDNS Client Subnet will be added") = "0.0.0.0/0, ::/0, " LOCAL_NETS_INVERSE;
     ::arg().set("ecs-scope-zero-address", "Address to send to allow-listed authoritative servers for incoming queries with ECS prefix-length source of 0") = "";
     ::arg().setSwitch("use-incoming-edns-subnet", "Pass along received EDNS Client Subnet information") = "no";
-    ::arg().setSwitch("pdns-distributes-queries", "If PowerDNS itself should distribute queries over threads") = "yes";
+    ::arg().setSwitch("pdns-distributes-queries", "If PowerDNS itself should distribute queries over threads") = "no";
     ::arg().setSwitch("root-nx-trust", "If set, believe that an NXDOMAIN from the root means the TLD does not exist") = "yes";
     ::arg().setSwitch("any-to-tcp", "Answer ANY queries with tc=1, shunting to TCP") = "no";
     ::arg().setSwitch("lowercase-outgoing", "Force outgoing questions to lowercase") = "no";
@@ -2759,8 +2759,11 @@ int main(int argc, char** argv)
     ::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.";
 
+#ifdef SO_REUSEPORT
+    ::arg().setSwitch("reuseport", "Enable SO_REUSEPORT allowing multiple recursors processes to listen to 1 address") = "yes";
+#else
     ::arg().setSwitch("reuseport", "Enable SO_REUSEPORT allowing multiple recursors processes to listen to 1 address") = "no";
-
+#endif
     ::arg().setSwitch("snmp-agent", "If set, register as an SNMP agent") = "no";
     ::arg().set("snmp-master-socket", "If set and snmp-agent is set, the socket to use to register to the SNMP daemon (deprecated)") = "";
     ::arg().set("snmp-daemon-socket", "If set and snmp-agent is set, the socket to use to register to the SNMP daemon") = "";