Wiki / Configuration Parameters

Controls whether huge pages are requested for the main shared memory area. Valid values are try (the default), on, and off. This parameter can only be set at server start. With huge_pages set to try, the server will try to request huge pages, but fall back to the default if that fails. With on, failure to request huge pages will prevent the server from starting up. With off, huge pages will not be requested. The actual state of huge pages is indicated by the server variable huge_pages_status. At present, this setting is supported only on Linux and Windows. The setting is ignored on other systems when set to try. On Linux, it is only supported when shared_memory_type is set to mmap (the default). The use of huge pages results in smaller page tables and less CPU time spent on memory management, increasing performance. For more details about using huge pages on Linux, see Section 18.4.5. Huge pages are known as large pages on Windows. To use them, you need to assign the user right “Lock pages in memory” to the Windows user account that runs PostgreSQL. You can use Windows Group Policy tool (gpedit.msc) to assign the user right “Lock pages in memory”. To start the database server on the command prompt as a standalone process, not as a Windows service, the command prompt must be run as an administrator or User Access Control (UAC) must be disabled. When the UAC is enabled, the normal command prompt revokes the user right “Lock pages in memory” when started. Note that this setting only affects the main shared memory area. Operating systems such as Linux, FreeBSD, and Illumos can also use huge pages (also known as “super” pages or “large” pages) automatically for normal memory allocation, without an explicit request from PostgreSQL. On Linux, this is called “transparent huge pages” (THP). That feature has been known to cause performance degradation with PostgreSQL for some users on some Linux versions, so its use is currently discouraged (unlike explicit use of huge_pages).

English manual coverage begins with PostgreSQL 7.4. Source history and runtime observations have their own recorded version boundaries.

boot val

try

category

Resource Usage / Memory

context

postmaster

documented

true

enumvals

off, on, try

extra desc

Unknown

lang

en

max val

Unknown

metadata version

18

min val

Unknown

name

huge_pages

short desc

Use of huge pages on Linux or Windows.

source

pg-settings-source-snapshot

unit

Unknown

vartype

enum