[src/trunk]: src/sys/net Increase default value for IFQ_MAXLEN from 50 to 256.

[jonathan <jonathan%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/292c41aab585
branches:  trunk
changeset: 574456:292c41aab585
user:      jonathan <jonathan%NetBSD.org@localhost>
date:      Mon Feb 28 18:44:45 2005 +0000

description:
Increase default value for IFQ_MAXLEN from 50 to 256.

The value of 50 dates back to 4.3BSD and 10Mbit interfaces.
Gigabit interfaces are 100x faster, and by observation, when heavy
interrupt mitigation is enabled, gigabit interfaces can enqueue 40 packets
or more in a single hardware interrupt.  So IFQ_MAXLEN of 256 is adequate
for at least four gigabit interfaces.

Increasing IFQ_MAXLEN discussed and approved, in priniciple, circa Apr 2004.
The value is sysctl'able, so the default is no longer so critical,
but (imho) best to tune for high-performane systems by default.

diffstat:

 sys/net/if.h |  4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diffs (18 lines):

diff -r c23a9e8e5db3 -r 292c41aab585 sys/net/if.h
--- a/sys/net/if.h      Mon Feb 28 18:04:54 2005 +0000
+++ b/sys/net/if.h      Mon Feb 28 18:44:45 2005 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if.h,v 1.101 2005/02/26 22:45:09 perry Exp $   */
+/*     $NetBSD: if.h,v 1.102 2005/02/28 18:44:45 jonathan Exp $        */
 
 /*-
  * Copyright (c) 1999, 2000, 2001 The NetBSD Foundation, Inc.
@@ -397,7 +397,7 @@
 #define        IF_IS_EMPTY(ifq)        ((ifq)->ifq_len == 0)
 
 #ifndef IFQ_MAXLEN
-#define        IFQ_MAXLEN      50
+#define        IFQ_MAXLEN      256
 #endif
 #define        IFNET_SLOWHZ    1               /* granularity is 1 second */