Speed up TCP retransmits (violates RFC)

Christoph Lameter (chris@lameter.com)
Mon, 14 Sep 1998 22:49:49 -0700 (PDT)


Here is a simple patch to speed up your tcp if you have to cross an ATM
network (which usually looses 10% of the packets)

The initial tcp timeout is reduced from 3 seconds to .5 seconds.

With this patch you have to wait .5 seconds for the first restransmit
instead of 3 seconds. A loss of a single packet does not have such a huge
impact anymore. I was rather frustrated with constant stalls especially
when remotely sysadmining Solaris boxes.

--- tcp.h Mon Sep 14 20:33:44 1998
+++ tcp.h~ Wed Sep 9 19:53:23 1998
@@ -283,7 +283,7 @@
* destroying a socket */
#define TCP_WRITE_TIME (30*HZ) /* initial time to wait for an ACK,
* after last transmit */
-#define TCP_TIMEOUT_INIT (HZ/2) /* RFC 1122 initial timeout value */
+#define TCP_TIMEOUT_INIT (3*HZ) /* RFC 1122 initial timeout value */
#define TCP_SYN_RETRIES 10 /* number of times to retry opening a
* connection (TCP_RETR2-....) */
#define TCP_PROBEWAIT_LEN (1*HZ)/* time to wait between probes when

-
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