BEA WebLogic Server Tuning Guide

The size of the QIO segment is determined by the configured physical memory on the system. For a system

configured with 4GB of physical memory, 512 MB of QIO segment is used. In addition, 512 MB of the process

address space is reserved for QIO segment, if the process is also a QIO client.

To overcome the problem of losing address space to QIO, the QIO segment can be configured to be moved to the

KSEG2

region. This means that the maximum size of the QIO segment is restricted to 128MB (instead of the

default 512 MB). Before making the decision to move QIO to KSEG2, check the current maximum QIO segment

size in use. If it is within 128 MB (optionally allowing for future requirements that might increase the QIO segment

size), QIO can be moved to KSEG2.

To determine the QIO segment size in use, use the following SCF command:

$ gtacl -p scf

SCF - T9082G02 - (30APR03) (01APR03) - 08/18/2003 08:45:04 System \TUXDV1

(Invoking \TUXDV1.$DATA02.VENKATR.SCFCSTM)

1-> status segment $ZM00,detail

QIO Detailed Status SEGMENT \TUXDV1.$ZM00

State.................. DEFINED

Segment State.......... STARTED

Segment Type........... RESIDENT

Segment Size........... 134217728

MDs in Use............. 3782

Max MDs Used........... 4752

Last Fail Size......... 0

Current Pool Size...... 16774788 Initial Pool Size...... 16776992

Max Pool Size.......... 16776992 Min Pool Size.......... 16776992

Current Pool Alloc..... 13910656 Max Pool Alloc......... 14254080

Current Pool Frags..... 126 Max Pool Frags......... 1056

The maximum QIO space used in this case is roughly 16MB, which is well below the 128MB limit. So, this can be

moved to KSEG2. In fact, the QIO segments in this system have already been moved to QIO based on the value of

Segment Type. The value is RESIDENT if QIO is moved to KSEG2 and FLAT_UA, if it has not been moved to

KSEG2.

Configuring the iTP WebServer and Plug-ins

When configuring iTP WebServer and the plug-in processes, make sure that the tuning information as provided in

the Tuning Guide for iTP WebServer is followed. A few key points are provided below. For more information on

these recommendations, see the iTP WebServer Tuning Guide.

1) Make sure that your iTP WebServer is configured to listen only on the TCP/IPV6 stack.

2) Make sure that the receive depth for the HTTPD servers are not over-configured. The recommended

depth is 50.

3) The maximum number of HTTP processes can be configured to be more than the number of processors

to provide for peak usage scenarios.

4) The plug-in processes are single-threaded. Therefore, there is a need to configure more plug-in

processes to handle the HTTP requests into WebLogic server.

When configuring QIO in KSEG2, carefully consider all the processes that will use the TCP/IP V6 stack and their

requirements. As mentioned above, when a process uses TCP/IP V6 stack, it becomes a QIO client. The iTP

WebServer and the WebLogic Server Plug-in for iTP WebServer are configured as Pathway serverclasses. iTP

KSEG2 is a special region of the privileged address space.