3.5 Enhancing DEC C Performance

The following sections include information on system tuning and explains how to install DEC C as a shared image.

3.5.1 Tuning Your System

After you install DEC C, you might want to adjust your system to enhance performance or lower the use of some system resources. General information about tuning an OpenVMS system is included in the Guide to OpenVMS Performance Management.

3.5.2 Installing DEC C as a Shared Image

If you expect DEC C to be used extensively on your system, you can reduce the system overhead and memory requirements by installing it as a shared image. To install DEC C as a shared image on a system that is currently running, use the OpenVMS INSTALL utility. It is recommended that you install DEC C as shared on a system that has been rebooted recently, because the available space in the global page table is less likely to be fragmented.

To install DEC C as a shared image:

1. Determine the number of available global pagelets and global sections on your system. You will need to increase them. Section 1.4.2 contains guidelines for showing and setting these parameters.

2. After you have reset the system parameter values, invoke the OpenVMS INSTALL utility from a privileged account and install DEC C as a shared image by entering the following commands:

   $ INSTALL
   INSTALL> ADD SYS$SYSTEM:DECC$COMPILER.EXE/OPEN/SHARED/HEADER_RESIDENT
   INSTALL> ADD SYS$MESSAGE:DECC$COMPILER_MSG.EXE/OPEN/SHARED/HEADER_RESIDENT
   INSTALL> EXIT
   

3. Add the following lines to the appropriate system startup command file so that DEC C is available as a shared image each time the system is started. (If your site has modularized its startup procedures, be sure you add the lines to the correct file.) The default startup command file for OpenVMS is SYS$MANAGER:SYSTARTUP_VMS.COM.

   $ INSTALL :== $INSTALL/COMMAND_MODE
   $ INSTALL
   ADD SYS$SYSTEM:DECC$COMPILER.EXE/OPEN/SHARED/HEADER_RESIDENT
   ADD SYS$MESSAGE:DECC$COMPILER_MSG.EXE/OPEN/SHARED/HEADER_RESIDENT
   EXIT