Add two loader tuneables that allow one to change the maximum number of

queue items that can be allocated by netgraph and the number of free queue
items that are cached on a private list.

Netgraph places an upper limit on the number of queue items it may allocate.
When there is a large number of netgraph messages travelling through the
system (100k/sec and more) there is a high probability, that messages get
queued at the nodes and netgraph runs out of queue items. In this case the data
flow through netgraph gets blocked. The tuneable for the number of free
items lets one trade memory for performance.

The tunables are also available as read-only sysctls.

PR:		kern/47393
Reviewed by:	julian
Approved by:	jake (mentor)

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/boot/forth/loader.conf b/sys/boot/forth/loader.conf
index 06a76f6b389e..73e42eb789fa 100644
--- a/sys/boot/forth/loader.conf
+++ b/sys/boot/forth/loader.conf
@@ -102,6 +102,8 @@ module_path="/boot/kernel;/boot/modules;/modules"	# Set the module search path
 #debug.ktr.cpumask="0xf"	# Bitmask of CPUs to enable KTR on
 #debug.ktr.mask="0x1200"	# Bitmask of KTR events to enable
 #debug.ktr.verbose="1"		# Enable console dump of KTR events
+#net.graph.maxalloc="128"	# Maximum number of queue items to allocate
+#net.graph.ngqfreemax="64"	# Maximum number of free queue items to cache
 
 
 ##############################################################