Browse Definitions:
Definition

second-level address translation (SLAT)

Contributor(s): Matthew Haughn

Second-level address translation (SLAT) is a hardware virtualization technology that reduces hypervisor overhead.

To do so, SLAT addresses the inefficiencies associated with looking up virtualized memory addresses in software shadow volumes. The technology exists as a CPU feature: an added translation lookaside buffer (TLB) that contains a real-time updated cache of virtualized memory addresses and their corresponding physical addresses.

Virtualization is a core technology for many data centers, but the software layer introduced by a hypervisor imposes computing overhead that reduces the resources available to virtual machines (VMs). Physical computing resources must be presented to VMs as virtualized resources -- this is the essence of abstraction, which insulates workloads from the underlying computing hardware. When retrieved from SLAT rather than through a standard look-up operation, performance is enhanced because the memory address is stored on processor. Latency is reduced and the system only goes through one memory look-up operation rather than two.

As memory is addressed in a virtualized system, values referenced are added to SLAT. The TLB holds recent page table mappings generated by the hypervisor. When a virtual-to-physical address translation is requested, the hypervisor queries the TLB for mapping information. If there's a match, the physical address is returned to the hypervisor -- without the memory and CPU resources that would be required for translation. This is the "second level" of address translation. If there is no match, the hypervisor checks the traditional page table and perform the normal address translation. The hypervisor will then save the new translation to the TLB for future reference. 

Both Intel and AMD support SLAT. Core i3, i5 and i7 all support what Intel calls their technology: extended page table (EPT). AMD processors include SLAT since their Barcelona architecture. AMD calls their SLAT rapid virtualization indexing (RVI). Both can offer performance increases of up to about 40 percent in heavy virtualization situations and even up to 600 percent in micro benchmarks.

There are a number of hypervisors that support SLAT, including KVM 2.6.26, VirtualBox 2 (and later), Vmware ESX 3.5 (and later), Xen 3.2.0 (and later). Bhyve and Windows 8-based systems not only support SLAT but require it.

 

This was last updated in August 2014

Continue Reading About second-level address translation (SLAT)

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

  • cyborg anthropologist

    A cyborg anthropologist is an individual who studies the interaction between humans and technology, observing how technology can ...

  • RegTech

    RegTech, or regulatory technology, is a term used to describe technology that is used to help streamline the process of ...

  • conduct risk

    Conduct risk is the prospect of financial loss to an organization that is caused by the actions of an organization's ...

SearchSecurity

  • security

    Security, in information technology (IT), is the defense of digital information and IT assets against internal and external, ...

  • insider threat

    An insider threat is a malicious hacker (also called a cracker or a black hat) who is an employee or officer of a business, ...

  • virus (computer virus)

    A computer virus is malicious code that replicates by copying itself to another program, computer boot sector or document.

SearchHealthIT

  • HIPAA Privacy Rule

    The Standards for Privacy of Individually Identifiable Health Information, commonly known as the HIPAA Privacy Rule, establishes ...

  • HIPAA business associate agreement (BAA)

    Under the U.S. Health Insurance Portability and Accountability Act of 1996, a HIPAA business associate agreement (BAA) is a ...

  • telemedicine

    Telemedicine is the remote delivery of healthcare services, such as health assessments or consultations, over the ...

SearchDisasterRecovery

  • data recovery

    Data recovery restores data that has been lost, accidentally deleted, corrupted or made inaccessible. Learn how data recovery ...

  • disaster recovery plan (DRP)

    A company's disaster recovery policy is enhanced with a documented DR plan that formulates strategies, and outlines preparation ...

  • fault-tolerant

    Systems with integrated fault tolerance are designed to withstand multiple hardware failures to ensure continuous availability.

SearchStorage

  • Secure Digital card (SD card)

    SD cards use flash memory to provide nonvolatile storage. They are more rugged than traditional storage media and are used in ...

  • data storage

    In a computer, storage is the place where data is held in an electromagnetic or optical form for access by a computer processor.

  • flash storage

    Flash-based storage, based on flash memory, is used for data repositories, storage systems and consumer devices, such as USB ...

SearchSolidStateStorage

  • flash file system

    Flash file systems are designed specifically for memory devices. A well-designed flash device and flash file system ensure ...

  • IOPS (input/output operations per second)

    IOPS measures the maximum number of reads and writes to non-contiguous storage. It is not an actual benchmark since vendor ...

  • eMMC (embedded MultiMediaCard)

    An embedded MultiMediaCard (eMMC) is a small storage device made up of NAND flash memory and a simple storage controller.

SearchCloudStorage

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

  • Zadara VPSA and ZIOS

    Zadara Storage provides block, file or object storage with varying levels of compute and capacity through its ZIOS and VPSA ...

Close