From: bert hubert <bert.hubert@netherlabs.nl>
Date: Fri, 5 Oct 2018 10:58:18 +0000 (+0200)
Subject: dnsdist did not set TCP_NODELAY, causing needless latency
X-Git-Tag: dnsdist-1.3.3~62^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=12894ed9b2d568e35c26a1afa14d2bb0a30e8ed3;p=thirdparty%2Fpdns.git

dnsdist did not set TCP_NODELAY, causing needless latency
Winfried and others noted that our TLS responses were super slow. This turned out to be caused by the Nagle
algorithm which we failed to disable. https://en.wikipedia.org/wiki/Nagle%27s_algorithm
---

diff --git a/pdns/dnsdist-tcp.cc b/pdns/dnsdist-tcp.cc
index d7a6e80bd4..0ea59d7911 100644
--- a/pdns/dnsdist-tcp.cc
+++ b/pdns/dnsdist-tcp.cc
@@ -32,6 +32,7 @@
 #include "threadname.hh"
 #include <thread>
 #include <atomic>
+#include <netinet/tcp.h>
 
 using std::thread;
 using std::atomic;
@@ -715,7 +716,7 @@ void* tcpAcceptorThread(void* p)
         continue;
       }
 #endif
-
+      SSetsockopt(ci->fd, SOL_TCP, TCP_NODELAY, 1); // disable NAGLE
       if(g_maxTCPQueuedConnections > 0 && g_tcpclientthreads->getQueuedCount() >= g_maxTCPQueuedConnections) {
         close(ci->fd);
         delete ci;