This note is to increase the kernel parameters for better performance in tcp connection on Linux red-hat.
First of all verify the system requirements to install WebCache in oracle.com, and check other required parameters like “kernel.sem” and “kernel.shmall”.
Tuning:
Add in /etc/sysctl.conf
net.ipv4.nonlocal_bind = 1
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_max_tw_buckets = 2000000
net.ipv4.tcp_sack = 0
net.ipv4.tcp_window_scaling = 0
net.ipv4.tcp_keepalive_time = 900
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_keepalive_intvl = 20
net.ipv4.tcp_fin_timeout = 10
net.ipv4.tcp_syn_retries = 5
net.ipv4.tcp_synack_retries = 5
net.ipv4.tcp_retries2 = 15
net.ipv4.tcp_wmem = 10000000 10000000 10000000
net.ipv4.tcp_rmem = 10000000 10000000 10000000
net.ipv4.tcp_mem = 10000000 10000000 10000000
net.core.wmem_default = 10000000
net.core.wmem_max = 10000000
net.core.rmem_default = 10000000
net.core.rmem_max = 10000000
net.core.hot_list_length = 20000
net.core.optmem_max = 10000000
net.core.hot_list_length = 20000
net.core.optmem_max = 10000000
net.core.netdev_max_backlog = 300000
NOTE:
You need to check with your network admin for firewall timeout value. Then you should modify kernel parameter net.ipv4.tcp_keepalive_time to a value lower than the firewall timeout values. This should give the TCP keepalive a chance to keep the connection alive.
On Linux, the keepalive procedures use three user-driven variables:
tcp_keepalive_time : How often TCP sends out keepalive messages when keepalive is enabled. Default is 7200 seconds.
tcp_keepalive_intvl : How frequent probes are retransmitted, when a probe isn’t acknowledged. Default :75 seconds
tcp_keepalive_probes : How many keepalive probes TCP will send, until it decides that the connection is broken. Default:9 seconds
If you need more information about webcache tuning : http://www.help2ora.com/index.php/2011/08/16/oracle-portal-performance
Good Luck !
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Great Article…. do you know of anywhere that has the same information for windows that you provide for Linux for the Webcache?
On Windows, only available kernel resources limit the number of file handles as well as socket handles – the size of paged and non-paged pools. However, the number of TCP ports the system can open restricts the number of active TCP/IP connections.
All versions of Windows, add the keys described below. Certain keys/values depend on the operating system installed (noted in the Value name column where different).
Subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\TCPIP\Parameters
Value name Value data Description
TcpTimedWaitDelay 0x0000001e
(Hex 0x0000001e = decimal 30. This value sets the wait time to 30 seconds.)
This key 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.
MaxUserPort (minimum) 32768 This key determines the highest port number that TCP/IP can assign when an application requests an available user port from the system.
TcpMaxDataRetranmission 5 (seconds) This key determines how many times TCP retransmits an unacknowledged data segment on an existing connection.
Subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters
Value name
Value data
Description
EnableDynamicBacklog 00000001
These keys, if many connection attempts are received simultaneously, increase the default number of pending connections that are supported by the operating system.
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.
MinimumDynamicBacklog 00000020
MaximumDynamicBacklog 00001000
DynamicBacklogGrowthDelta 00000010
KeepAliveInterval 1 (second) This key determines how often TCP repeats keep-alive transmissions when no response is received.
Subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{Interface GUID}*
* {Interface GUID} is different for every system.
Value name
Value data
Description
TcpNoDelay
(Windows 2008 R1 & R2 only) 1 0 to enable Nagle’s algorithm, 1 to disable, not present by default
TcpAckFrequency
(Windows XP, Windows 2003, and Windows 2008 R1 & R2) 1 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.
NOTE: Some documentation states that this value may be placed directly under HKLM\SYSTEM\CurrentControlSet\Services\Tcpip or HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters. After testing, it was determined that the setting only takes effect when placed under the actual {Interface GUID} key.
Your .reg file for Windows 2008 would look something like this:
Remember to reboot the server computer after making the registry changes.
On Windows 2008 (R1&R2), you must also disable autotuning:
Open a command prompt and execute the following command:
netsh int tcp set global autotuninglevel=disabled
The default level is “normal.” The possible settings include:
disabled: uses a fixed value for the tcp receive window. Limits it to 64KB (limited at 65535).
highlyrestricted: allows the receive window to grow beyond its default value, very conservatively
restricted: somewhat restricted growth of the tcp receive window beyond its default value
normal: default value, allows the receive window to grow to accommodate most conditions
experimental: allows the receive window to grow to accommodate extreme scenarios (not recommended as it can degrade performance in common scenarios; only intended for research purposes. It enables RWIN values of over 16 MB)