This topic describes how to tune Windows® 2000, Windows XP, Windows 2003, Windows 2008
and Windows Vista operating systems to optimize
the performance of WebSphere® Application Server.
Because Windows operating systems are
not WebSphere Application Server products,
be aware that the products can change and results can vary.
About this task
When you have a performance concern, check the operating
system settings to determine if they are appropriate for your application.
Procedure
Configure the following settings or variables according
to your specific tuning needs:
- TcpTimedWaitDelay
- Description: Determines the time that must elapse before
TCP/IP can release a closed connection and reuse its resources. This
interval between closure and release is known as the TIME_WAIT state
or twice the maximum segment lifetime (2MSL) state. During this time,
reopening the connection to the client and server costs less than
establishing a new connection. By reducing the value of this entry,
TCP/IP can release closed connections faster and provide more resources
for new connections. Adjust this parameter if the running application
requires rapid release, the creation of new connections, or an adjustment
because of a low throughput caused by multiple connections in the
TIME_WAIT state.
- How to view or set:
- Use the regedit command, access the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TCPIP\Parameters registry subkey, and create a new REG_DWORD
value named TcpTimedWaitDelay.
- Set the value to decimal 30, which is Hex 0x0000001e.
This value sets the wait time to 30 seconds.
- Stop and restart the system.
- Default value: 0xF0, which sets the wait time
to 240 seconds (4 minutes).
- Recommended value: A minimum value of 0x1E, which
sets the wait time to 30 seconds.
- MaxUserPort
Avoid trouble: ![[Updated in December 2010]](../../delta.gif)
This
setting is not needed for the Windows 2008
and Windows Vista operating systems. The default
start port for these operating systems is 49152, and the default end
port is 65535. See the Microsoft Support web site for more information.
![[Updated in December 2010]](../../deltaend.gif)
dec2010
gotcha
- Description: Determines the highest port number that TCP/IP
can assign when an application requests an available user port from
the system.
- How to view or set:
- Use the regedit command, access the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TCPIP\Parameters registry subkey, and create a new REG_DWORD
value named MaxUserPort.
- Set this value to at least decimal 32768.
- Stop and restart the system.
- Default value: None
- Recommended value: At least decimal 32768.
- MaxConnect Backlog
- Description: If many connection attempts are received
simultaneously, increase the default number of pending connections
that are supported by the operating system.
- How to view or set:
- Use the regedit command and access the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters
registry subkey
- Create and set (and create if necessary) the following values:
"EnableDynamicBacklog"=dword:00000001
"MinimumDynamicBacklog"=dword:00000020
"MaximumDynamicBacklog"=dword:00001000
"DynamicBacklogGrowthDelta"=dword:00000010
- These values request a minimum of 20 and a maximum of 1000 available
connections. The number of available connections is increased by
10 each time that there are fewer than the minimum number of available
connections.
- Stop and restart the system.
- TPC/IP acknowledgements
TCP/IP can be the source of some significant remote method
delays. You can increase TCP performance by immediately acknowledging
incoming TCP segments, in all situations.
Complete the following
steps to immediately acknowledge incoming TCP segments on a server
that runs a Microsoft Windows 2000 operating system:
- Start the Registry Editor (regedit.exe).
- Locate and click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\
- On the Edit menu, click Add Value, and create the following
registry value:
Value name: TcpDelAckTicks
Data type: REG_DWORD
Value data: 0
Quit Registry Editor.
- Restart your Windows operating system.
Similarly, to immediately acknowledge incoming TCP segments
on a server that runs a Microsoft Windows XP or Windows Server 2003
operating system:
- Start the Registry Editor (regedit.exe).
- Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\
- On the Edit menu, click New > DWORD Value.
- Name the new value, TcpAckFrequency, and assign it a
value of 1.
- Close the Registry Editor.
- Restart your Windows operating system.
- Large page support
- Description: Using large pages can reduce the CPU overhead
of managing a large JVM heap.
- How to view or set: The Windows operating system provides
large page support by default. Use the -Xlp JVM option to
make use of this support.
Results
This tuning procedure improves performance of WebSphere Application
Server on Windows 2000, Windows XP, and Windows 2003 operating systems.
What to do next
After tuning your operating system for performance, consult
other tuning topics for various tuning tips.