get_mempolicy - Linux

Overview

get_mempolicy is a system utility designed for inspecting the memory policy settings for a specified process or address range within the process address space. This command grants insights into how the kernel allocates pages of memory and facilitates manipulation of specific memory policies.

Syntax

get_mempolicy [options] PID [addr range]

Options/Flags

Required arguments:

  • PID: Specify the process ID of the process whose memory policy needs to be examined.
  • addr range (optional): Optionally specify the address range within the process’s address space for which memory policy should be retrieved. If omitted, policies for the entire process are displayed.

Other options:

  • -c, --canonical: Display the policy in a canonical format.
  • -f, --force: Force the display of the policy even if the process is running in a non-user namespace and the caller does not have CAP_SYS_ADMIN.
  • -m, --mempolicy: Display the policy in the form of a bitmask.
  • -v, --verbose: Print additional informational messages.
  • -h, --help: Display a help message and exit.
  • -V, --version: Display the version information and exit.

Examples

  • To view the memory policy for a process with PID 1234:
get_mempolicy 1234
  • To display the memory policy for a specific address range within a process:
get_mempolicy 1234 0x10000-0x20000
  • To view the policy in canonical format:
get_mempolicy -c 1234

Common Issues

  • Permission denied: If you do not have sufficient permissions (CAP_SYS_ADMIN) or the process is running in a different user namespace, you may not be able to retrieve the memory policy. Use the -f option to force the display of the policy.
  • Invalid address range: If the specified address range is invalid or outside the process’s address space, the command will return an error.

Integration

get_mempolicy can be integrated with other tools and scripts for advanced tasks:

  • Use the output of get_mempolicy as input to other commands or scripts that require information about the process’s memory policy.
  • Combine get_mempolicy with set_mempolicy to adjust the memory policy for a process or address range.

Related Commands

  • set_mempolicy: Modify the memory policy of a process or address range.
  • mbind: Bind memory pages to specified NUMA nodes.
  • numactl: Control and query NUMA-related settings.

Linux man page for get_mempolicy