[master] delayed-ack is now compiled in by default

    Merges in rt42444.

2 files changed, 17 insertions, 15 deletions

diff --git a/server/dhcp.c b/server/dhcp.c
index bbe97b31..3396ebad 100644
--- a/server/dhcp.c
+++ b/server/dhcp.c
@@ -3574,7 +3574,7 @@ void ack_lease (packet, lease, offer, when, msg, ms_nulltp, hp)
 	} else {
   		lease->cltt = cur_time;
 #if defined(DELAYED_ACK) && !defined(DHCP4o6)
-		if (enqueue)
+		if (enqueue && max_outstanding_acks != 0)
 			delayed_ack_enqueue(lease);
 		else 
 #endif
diff --git a/server/dhcpd.conf.5 b/server/dhcpd.conf.5
index 1ea87396..f2b6fa49 100644
--- a/server/dhcpd.conf.5
+++ b/server/dhcpd.conf.5
@@ -2267,26 +2267,28 @@ statements
 .B max-ack-delay \fImicroseconds\fR\fB;\fR
 .PP
 .I Count
-should be an integer value from zero to 2^16-1, and defaults to 28.  The
-count represents how many DHCPv4 replies maximum will be queued pending
-transmission until after a database commit event.  If this number is
-reached, a database commit event (commonly resulting in fsync() and
-representing a performance penalty) will be made, and the reply packets
-will be transmitted in a batch afterwards.  This preserves the RFC2131
-direction that "stable storage" be updated prior to replying to clients.
-Should the DHCPv4 sockets "go dry" (select() returns immediately with no
-read sockets), the commit is made and any queued packets are transmitted.
+should be an integer value from zero to 2^16-1 and defaults to 0, which means
+that the feature is disabled.  Otherwise, 28 may be a sensible starting point
+for many configurations (SO_SNDBUF size / 576 bytes.)  The count represents how
+many DHCPv4 replies maximum will be queued pending transmission until after a
+database commit event.  If this number is reached, a database commit event
+(commonly resulting in fsync() and representing a performance penalty) will be
+made, and the reply packets will be transmitted in a batch afterwards.  This
+preserves the RFC2131 direction that "stable storage" be updated prior to
+replying to clients.  Should the DHCPv4 sockets "go dry" (select() returns
+immediately with no read sockets), the commit is made and any queued packets
+are transmitted.
 .PP
 Similarly, \fImicroseconds\fR indicates how many microseconds are permitted
 to pass inbetween queuing a packet pending an fsync, and performing the
 fsync.  Valid values range from 0 to 2^32-1, and defaults to 250,000 (1/4 of
 a second).
 .PP
-The delayed-ack feature is not compiled in by default, but must be enabled
-at compile time with \'./configure --enable-delayed-ack\'.  While we no
-longer consider it experimental and we don't know of any issues with it,
-in order to minimize problems with existing configuration files we have
-left it disabled by default.
+The delayed-ack feature is compiled in by default, but can be disabled
+at compile time with \'./configure --disable-delayed-ack\'.  Please note
+that the delayed-ack feature is not currently compatible with support for
+DHPCv4o6 (compiled out by default).  You must compile with one or the
+other but not both.
 .RE
 .PP
 The