This page describes preliminary SIP servlet tuning for Linux 2.6
kernel.
Before you begin
A Session Initiation Protocol (SIP) servlet under load might retransmit
messages or drop calls. The UDP socket queues might fill. A review of the
verbose garbage collection output might show that there are fairly long garbage
collection times, for example, 0.5 to 1.5 seconds. The cause of this problem
is that the Ethernet driver, Linux® operating system, WebSphere® Application
Server, or any combination of the items are not tuned for SIP applications.
You can apply the following levels of tuning.
Note: The following recommendations
have been tested on Red Hat Enterprise Linux 4 only and are provided as is
without any implied warranty.
About this task
Linux Ethernet driver
Linux Ethernet driver tuning
begins by selecting the best Ethernet driver. For example, the HS20 blades
recommended driver is the tg3-3.43b driver (or later), which can be found
at the Web site for Broadcom Ethernet NIC Driver Downloads. The following
shell commands have been used to tune the Linux kernel Ethernet driver:
/sbin/ifconfig eth0 txqueuelen 2000
/sbin/ifconfig eth1 txqueuelen 2000
ethtool -s eth0 autoneg off speed 1000 duplex full
ethtool -A eth0 autoneg off rx on tx on
ethtool -C eth0 adaptive-rx off adaptive-tx off rx-
usecs 20 rx-frames 5 tx-usecs 60 tx-frames 11
ethtool -G eth0 rx 511 rx-jumbo 255 tx 511
Depending upon the Ethernet driver that is installed, some of these
options might need to change.
Linux kernel
Linux kernel tuning
uses the following commands:
echo 1048576 > /proc/sys/net/core/rmem_max
echo 1048576 > /proc/sys/net/core/rmem_default
echo 1048576 > /proc/sys/net/core/wmem_max
echo 1048576 > /proc/sys/net/core/wmem_default
echo 10000000 > /proc/sys/net/core/optmem_max
echo 262143 262143 262143 > /proc/sys/net/ipv4/tcp_rmem
echo 262143 262143 262143 > /proc/sys/net/ipv4/tcp_wmem
echo 8388608 8388608 8388608 > /proc/sys/net/ipv4/tcp_mem
echo 400 > /proc/sys/net/unix/max_dgram_qlen
echo 400 > /proc/sys/net/core/message_burst
echo 2800 > /proc/sys/net/core/mod_cong
echo 1000 > /proc/sys/net/core/lo_cong
echo 200 > /proc/sys/net/core/no_cong
echo 2900 > /proc/sys/net/core/no_cong_thresh
echo 3000 > /proc/sys/net/core/netdev_max_backlog
This configuration might not be optimum for a given application and
you might need to adjust the configuration to achieve the best performance.
However, you might use these values as a starting point.
SIP for WebSphere
Application Server
SIP tuning for WebSphere Application Server is
completed using the following steps:
- Create a separate thread pool for the SIP servlet container. Follow this
path in the administrative console:
- Click .
- Under Additional properties, click .
- In the Name field, enter SipContainer.
- In the Minimum Size and Maximum Size fields, enter 15.
These values should be adequate for most applications.
- Click .
- Create custom properties for the SIP Servlet container. Follow this path
in the administrative console:
- Click .
- Click .
- Under ,
click .
- In the Name field, enter javax.sip.max.object.pool.size.
- In the Value field, enter 1000.
- Click .
- In the Name field, enter max.tu.pool.size.
- In the Value field, enter 1000.
- Click .
- Create custom properties for the SIPUDP channel if User Datagram Protocol
(UDP) is the primary transport for SIP traffic. Follow this path in the administrative
console:
- Click .
- Click .
- Under ,
click .
- In the Name field, enter receiveBufferSocketSize.
- In the Value field, enter 3000000.
- Click OK.
- In the Name field, enter sendBufferSocketSize.
- In the Value field, enter 3000000.
- Specify the SIP servlet container general properties. Follow this path
in the administrative console:
- Click .
- Enter the Maximum application sessions value. The Maximum application
sessions value can be calculated as: Maximum call hold time or session
timeout x Call rate x Safety factor.
- Enter the Maximum messages per averaging period value. The Maximum messages
per averaging period value can be calculated as: Maximum call hold
time or session timeout x Maximum rate of SIP messages x Safety factor.
- Enter the Maximum dispatch queue size value. The Maximum dispatch queue
size value can be calculated as: Maximum rate of SIP messages x Maximum
latency in SIP processing x Safety factor.
- Set the thread pool to the newly created SIP container thread pool (to
the drop down name "SipContainer").
- Tune the Java virtual machine (JVM) garbage collection policy. Follow
this path in the administrative console:
- Click .
- Under Server Infrastructure, click .
Click Control.
- Under ,
click .
- In the Generic JVM arguments field, enter the following value as one continuous
line: 1"-Xgcpolicy:gencon -Xgc:scvNoAdaptiveTenure,scvTenureAge=8,
stdGlobalCompactToSatisfyAllocate".
Optional: You also might add a value of 768 to the Initial Heap
Size and Maximum Heap Size fields. It is also a good practice to enable the option during
performance testing or tuning operations.