free_hugepages - Linux

Overview

free_hugepages is a utility command used to release huge pages from the system back to the hugepage pool. It is designed to enable administrators to reclaim memory resources previously allocated for huge pages and make them available for other applications or use cases.

Syntax

free_hugepages [-d hugepage_size] [-n count] [-a] [-h]

Options/Flags

  • -d hugepage_size (Required): Specifies the size of the huge pages to release. Valid options are 2MB, 1GB, or 2GB.

  • -n count: Specifies the number of huge pages to release. By default, it is set to 0, which releases all huge pages.

  • -a: This option releases all huge pages regardless of their size.

  • -h: Displays help information.

Examples

Release all 2GB huge pages from the system:

free_hugepages -d 2GB

Release 100 1GB huge pages from the system:

free_hugepages -d 1GB -n 100

Common Issues

  • Insufficient privileges: Ensure that the command is run with root privileges or via ‘sudo’.

  • Invalid huge page size: Verify that the specified huge page size is supported by the system.

  • Resource contention: If other applications are still using huge pages, freeing them may fail. Close all applications that may be using huge pages before running the command.

Integration

free_hugepages can be used in conjunction with other commands to create automated scripts for memory management. For example, it can be combined with the hugeadm command to query and monitor huge page usage.

Related Commands

  • hugeadm: Manages huge page memory on Linux systems.
  • top: Displays real-time process and system information.
  • vmstat: Displays virtual memory statistics.