svn commit: r360510 - in stable/12: share/man/man7 sys/netinet

[Richard Scheffenegger]

Author: rscheff
Date: Thu Apr 30 21:16:08 2020
New Revision: 360510
URL: https://svnweb.freebsd.org/changeset/base/360510

Log:
  MFC r360010: Reduce the delayed ACK timeout from 100ms to 40ms.
  
  Reviewed by:	kbowling, tuexen
  Approved by:	tuexen (mentor)
  MFC after:	2 weeks
  Sponsored by:	NetApp, Inc.
  Differential Revision:	https://reviews.freebsd.org/D23281

Modified:
  stable/12/share/man/man7/tuning.7
  stable/12/sys/netinet/tcp_timer.h
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/share/man/man7/tuning.7
==============================================================================
--- stable/12/share/man/man7/tuning.7	Thu Apr 30 21:09:01 2020	(r360509)
+++ stable/12/share/man/man7/tuning.7	Thu Apr 30 21:16:08 2020	(r360510)
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 30, 2017
+.Dd April 16, 2020
 .Dt TUNING 7
 .Os
 .Sh NAME
@@ -435,7 +435,7 @@ number of tiny packets flowing across the network in h
 The
 .Fx
 delayed ACK implementation also follows the TCP protocol rule that
-at least every other packet be acknowledged even if the standard 100ms
+at least every other packet be acknowledged even if the standard 40ms
 timeout has not yet passed.
 Normally the worst a delayed ACK can do is
 slightly delay the teardown of a connection, or slightly delay the ramp-up

Modified: stable/12/sys/netinet/tcp_timer.h
==============================================================================
--- stable/12/sys/netinet/tcp_timer.h	Thu Apr 30 21:09:01 2020	(r360509)
+++ stable/12/sys/netinet/tcp_timer.h	Thu Apr 30 21:16:08 2020	(r360510)
@@ -119,7 +119,7 @@
 
 #define	TCP_MAXRXTSHIFT	12			/* maximum retransmits */
 
-#define	TCPTV_DELACK	( hz/10 )		/* 100ms timeout */
+#define	TCPTV_DELACK	( hz/25 )		/* 40ms timeout */
 
 /*
  * If we exceed this number of retransmits for a single segment, we'll consider