Example: Configuring Virtual Memory for Process Configuration Data

Requirements

• A Juniper Networks M Series, MX Series, PTX Series, or T Series router

• Junos OS Release 13.2 or later

Overview

Typically, the maximum database size available for storing configuration data per process is 665.99 MB for M, MX, PTX, and T i386 platforms, with certain devices such as the PTX1000 Packet Transport Router having a maximum database size of 409.99 MB. The database size is mapped within the address space reserved for that process. Depending on the process, this database size might impact commit performance for a process that manages many changes at commit. To improve commit performance, you can use virtual-memory-mapping at the [edit system configuration-database] hierarchy level to allocate virtual memory for storing process configuration data on a per-process basis. You can configure a portion of the virtual memory as fixed size and a portion for page-pooling. Page-pooling uses just a small amount of memory to swap pages in or out as needed, rather than mapping the entire configuration database at once.

Using virtual-memory-mapping and enabling page-pooling are methods used to improve commit performance for processes that manage many changes at commit time that negatively impact commit performance.

Additionally, for M, MX, PTX, and T i386 systems, the option extend-size is available at the [edit system configuration-database] hierarchy level to increase the configuration database size, improving commit performance for mgd. The extended default size is based on the original default database size. A device with a default database size of 409.99 MB will extend to a maximum of 1049.99 MB, and a device with a default database size of 665.99 MB will extend to a maximum of 1305.99. The extended size will automatically be used by mgd. Other processes will only be able to access the increased size by using page-pooling. The extend-size option is not available on MX80, MX40, MX10, or MX5 platforms.

The configurations provided here are only examples. The sizes and processes that you configure will be different depending on the needs of your system.

Syntax

The syntax structure used in this example is available in Junos OS Release 13.2 or later.

Configuration

• Configuring Virtual Memory Parameters for a Single Process

• Configuring Virtual Memory Parameters for Multiple Processes

• Configuring Extended Size for the Configuration Database

Configuring Virtual Memory Parameters for a Single Process

Step-by-Step Procedure

1. Set the virtual memory fixed size to 512 KB and the page-pooling size to 512 KB for the interface-control process.
2. Commit the changes.

Results

Verify the setup using the show system configuration-database command.

Configuring Virtual Memory Parameters for Multiple Processes

Step-by-Step Procedure

1. Set the fixed-size to 20480 and set the page-pooling size to 30720 for the interface-control process.
2. Set the fixed-size to 512 and set the page-pooling size to 30720 for the mib-process.
3. Set the fixed-size to 30720 and set the page-pooling size to 1024 for the firewall process.
4. Set the fixed-size to 10240 and set the page-pooling size to 10240 for the snmp process.
5. Commit the changes.

Results

Verify the setup using the show system configuration-database command.

Configuring Extended Size for the Configuration Database

Step-by-Step Procedure

1. Extend the configuration database size.
2. Commit the changes.

Results

Verify the setup using the show system configuration-database command. For brevity, this show output includes only the configuration that is relevant to this example.