IBM G210-1784-00 manual Tuning the IBM HTTP Server, MaxPoolThreads and PoolThreadLimit parameter

Use the registry editor to set the ListenBackLog parameter located at:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\InetInfo\Parameters\ListenBack Log

The recommended value is 200.

MaxPoolThreads and PoolThreadLimit parameter

The MaxPoolThreads parameter controls the number of threads per CPU in the thread pool available for IIS to run Common Gateway Interface (CGI) processes (each process takes one thread). The PoolThreadLimit parameter specifies the upper limit for MaxPoolThreads.

The default thread limit that IIS can create on a machine is twice the number of MB in RAM on a machine (for example, a server with 512 MB of RAM is limited to1024 threads).

Use the registry editor and adjust the following values:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\InetInfo\Parameters \MaxPoolThreads

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\InetInfo\Parameters \PoolTheadLimit

Tuning the IBM HTTP Server

The IBM HTTP Server (IHS) is a multi-process, single-threaded server. For more information about tuning IHS, see the Hints on Running a high-performance Web server at: http://www.software.ibm.com/webservers/httpservers/doc/v136/misc/perf.html

The configuration takes place in the IHS httpd.conf file located in the confdirectory of the Web server’s installation directory. After setting the described parameters, you have to restart IHS.

Adjust the following IBM HTTP Server properties and parameters to tune your server performance.

MinSpareServers, MaxSpareServers, StartServers, and MaxClients

During heavy load, IHS can use a large amount of the server’s processing time to create and destroy httpd child processes. For optimum performance, even under heavy load, specify the same value for all four parameters. This avoids the time-costly recreation of sub-processes.

Ignore the appearing error message [error] server reached MaxClients setting. Consider raising the MaxClient when restarting IHS.

A too-low number of child processes is as bad as a too-high number, because more processes also means more memory usage and more processor time for managing the processes. You can use the Apache Benchmark (ab) program located in the IHS bin directory to test the impact of different parameter settings.

To simulate 100 concurrent users performing 20 requests to LMS, for example, you can issue the following command:

ab -n 20 -c 100 http://<hostname>/lms-lmm/studentCatalog.do

In the ab command’s summary, some fields of interest may be the following:

•Complete requests

•Failed requests

•Requests per second

Appendix A: LMS Performance and Fine-tuning Information 111