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

SearchCompliance

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

  • audit program (audit plan)

    An audit program, also called an audit plan, is an action plan that documents what procedures an auditor will follow to validate ...

SearchSecurity

  • insider threat

    Insider threat is a generic term for a threat to an organization's security or data that comes from within.

  • ransomware

    Ransomware is a subset of malware in which the data on a victim's computer is locked, typically by encryption, and payment is ...

  • hacker

    A hacker is an individual who uses computer, networking or other skills to overcome a technical problem.

SearchHealthIT

SearchDisasterRecovery

  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

SearchStorage

SearchSolidStateStorage

  • 3D XPoint

    3D XPoint is memory storage technology jointly developed by Intel and Micron Technology Inc.

  • RRAM or ReRAM (resistive RAM)

    RRAM or ReRAM (resistive random access memory) is a form of nonvolatile storage that operates by changing the resistance of a ...

  • JEDEC

    JEDEC is a global industry group that develops open standards for microelectronics.

SearchCloudStorage

  • Google Cloud Storage

    Google Cloud Storage is an enterprise public cloud storage platform that can house large unstructured data sets.

  • 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 ...

Close