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What is Oracle Hugepages?

by Lennon Wade

What is Oracle Hugepages?

HugePages is a feature integrated into the Linux kernel 2.6. Enabling HugePages makes it possible for the operating system to support memory pages greater than the default (usually 4 KB).

How do I enable Hugepages in Linux?

Execute ‘sysctl -p’ command to enable the hugepages parameter. Note : It’s recommended to restart the system after configuring hugepages as the chances of having free contiguous memory (for hugepages allocation) is much greater when a system is started.

How do I set up Hugepages?

So lets get started and come to the 7 steps:

  1. Check Physical Memory. First we should check our „physical“ available Memory.
  2. Check Database Parameter. Second check your database parameter.
  3. Check Hugepagesize.
  4. Calculate Hugepages.
  5. Change Server Configuration.
  6. Server Reboot.
  7. Check Configuration.

Does Oracle PGA use HugePages?

The short answer. No, it doesn’t.

Does Oracle PGA use Hugepages?

How do I know if HugePages is enabled?

How to tell if Explicit HugePages is enabled or disabled

  1. If the value of HugePages_Total is greater than “0”, it means HugePages is enabled on the system:
  2. Similarly if the value in /proc/sys/vm/nr_hugepages file or vm.nr_hugepages sysctl parameter is greater than “0”, it means HugePages is enabled on the system:

What are hugepages for Oracle on Linux?

Configuring HugePages for Oracle on Linux (x86-64) Introduction. For large SGA sizes, HugePages can give substantial benefits in virtual memory management. Without HugePages, the memory of the SGA is divided into 4K pages, which have to be managed by the Linux kernel.

What is the maximum size of a huge page in Oracle?

HugePage sizes vary from 2 MB to 256 MB, depending on the kernel version and the hardware architecture. For Oracle Databases, using HugePages reduces the operating system maintenance of page states, and increases Translation Lookaside Buffer (TLB) hit ratio.

What is the maximum size of a hugepage?

HugePages is useful for both 32-bit and 64-bit configurations. HugePage sizes vary from 2 MB to 256 MB, depending on the kernel version and the hardware architecture. For Oracle Databases, using HugePages reduces the operating system maintenance of page states, and increases Translation Lookaside Buffer (TLB) hit ratio.

What are hugepages and how do they work?

Using HugePages, the page size is increased to 2MB (configurable to 1G if supported by the hardware), thereby reducing the total number of pages to be managed by the kernel and therefore reducing the amount of memory required to hold the page table in memory.