Technical Documentation

Configuring Memory Settings

Configuring memory can help tune application performance. Four memory settings are available for SDK applications: object cache, forwarding database, policy database, and wired process memory.

[edit chassis fpc slot-number pic pic-number adaptive-services service-package]extension-provider {forwarding-db-size size;object-cache-size value;policy-db-size size;wired-process-mem-size size;}

Note: You need to include the sampling statement at the [edit forwarding-options] hierarchy level for the forwarding database to be created. For information on configuring this statement, see Configuring Traffic Sampling for JUNOS SDK Applications.

The policy-db-size statement defines the size of policies that providers expect to be present in their system. It is configured in megabytes (MB). The forwarding database, also configured in MB, provides access to route information. Both the forwarding database and the policy database are carved out of object cache. So both databases should be less than object cache and their total size together should also be less than the value for the object-cache-size statement (PDB + FDB <= object cache). Wired process memory is memory used by the operating system that is generally “off limits” to another application.

For the object cache, specify a value that is a multiple of 128 MB and up to 512 MB for the Multiservices 100 PIC or up to 1280 MB for the Multiservices 400 PIC. However, if you set wired process memory as well, the maximum value for the object cache on the Multiservices 100 PIC is 128 MB and 768 MB on the Multiservices 400 PIC.

For the policy database, the current recommendations when configuring Multiservices PICs are:

  • Do not exceed a policy database size of 64 MB.
  • Stay with one rule per term.
  • Keep the object cache size high (1280 MB on Multiservices 400 PICs and DPCs and 512 MB on Multiservices 100 PICs).
  • Do not configure anything for forwarding database.
  • Keep the number of service sets per Multiservices PIC below 1000. (For more on service sets, see Configuring Service Sets for JUNOS SDK Applications.)

To configure wired process memory size, specify 512 MB for the wired-process-mem-size statement at the [edit chassis fpc slot-number pic pic-number adaptive-services service-package extension-provider] hierarchy level. In addition, you can also configure the object cache.

Note: When the extension-provider statement is first configured, the PIC reboots. Changing the object cache size, the policy database size, or the FDB size on a running system causes the PIC to reboot.


Published: 2010-05-09