X86 virtualization

Résumé

x86 virtualization is the use of hardware-assisted virtualization capabilities on an x86/x86-64 CPU. In the late 1990s x86 virtualization was achieved by complex software techniques, necessary to compensate for the processor's lack of hardware-assisted virtualization capabilities while attaining reasonable performance. In 2005 and 2006, both Intel (VT-x) and AMD (AMD-V) introduced limited hardware virtualization support that allowed simpler virtualization software but offered very few speed benefits. Greater hardware support, which allowed substantial speed improvements, came with later processor models. Software-based virtualization The following discussion focuses only on virtualization of the x86 architecture protected mode. In protected mode the operating system kernel runs at a higher privilege such as ring 0, and applications at a lower privilege such as ring 3. In software-based virtualization, a host OS has direct access to hardware while the guest OSs have limite

Source officielle

https://en.wikipedia.org/wiki/X86_virtualization

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Publications associées (9)

Publications associées

Chargement

Personnes associées (1)

Personnes associées

Chargement

Unités associées (2)

Unités associées

Chargement

Concepts associés (29)

La famille x86 regroupe les microprocesseurs compatibles avec le jeu d'instructions de l'Intel 8086. Cette série est nommée IA-32 (pour Intel architecture 32 bits) par Intel pour ses processeurs à pa

x86-64, ou x64, est une extension du jeu d'instructions x86 d'Intel, introduite par la société AMD avec la gamme AMD64. Intel utilisera cette extension en l'appelant initialement EM64T renommé aujourd

Intel Corporation est une entreprise américaine fondée en 1968 par Gordon Moore, Robert Noyce et Andrew Grove. Elle est le second fabricant mondial de semi-conducteurs après Samsung si on se fonde sur

Afficher plus

Concepts associés

Chargement

Cours associés (1)

Introduction to basic concepts of operating systems.

Cours associés

Chargement

Séances de cours associées (2)

Séances de cours associées

Chargement

Performance Profiling of Virtual Machines

Jiaqing Du, Willy Zwaenepoel

Profilers based on hardware performance counters are indispensable for performance debugging of complex software systems. All modern processors feature hardware performance counters, but current virtual machine monitors (VMMs) do not properly expose them to the guest operating systems. Existing profiling tools require privileged access to the VMM to profile the guest and are only available for VMMs based on paravirtualization. Diagnosing performance problems of software running in a virtualized environment is therefore quite difficult. This paper describes how to extend VMMs to support performance profiling. We present two types of profiling in a virtualized environment: guest-wide profiling and system-wide profiling. Guest-wide profiling shows the runtime behavior of a guest. The profiler runs in the guest and does not require privileged access to the VMM. System-wide profiling exposes the runtime behavior of both the VMM and any number of guests. It requires profilers both in the VMM and in those guests. Not every VMM has the right architecture to support both types of profiling. We determine the requirements for each of them, and explore the possibilities for their implementation in virtual machines using hardware assistance, paravirtualization, and binary translation. We implement both guest-wide and system-wide profiling for a VMM based on the x86 hardware virtualization extensions and system-wide profiling for a VMM based on binary translation. We demonstrate that these profilers provide good accuracy with only limited overhead.

2011

Chargement

HAVC-II - Idiap Private Cloud (Technical Inside-Out)

Virtualizing resources – servers, storage, networks – is now part of every IT departments life. The benefits of virtualization no longer need to be demonstrated and, when played upon in a large scale, provide both the saddle and spurs with which the Cloud mantra has been riding towards its success. This document shall describe how Idiap took advantage of its infrastructure to build its own virtualization farm, which shall (shamelessly) be referred to as Idiap Private Cloud.

Idiap2015

Chargement

In recent years, there has been a rapid growth in the adoption of virtual machine technology in data centers and cluster environments. This trend towards server virtualization is driven by two main factors: the savings in hardware cost that can be achieved through the use of virtualization, and the increased flexibility in the management of hardware resources in a cluster environment. An important consequence of server virtualization is the negative impact it has on the networking performance of server applications running in virtual machines (VMs). In this thesis, we address the problem of efficiently virtualizing the network interface in Type-II virtual machine monitors. In the Type-II architecture, the VMM relies on a special, 'host' operating system to provide the device drivers to access I/O devices, and executes the drivers within the host operating system. Using the Xen VMM as an example of this architecture, we identify fundamental performance bottlenecks in the network virtualization architecture of Type-II VMMs. We show that locating the device drivers in a separate host VM is the primary reason for performance degradation in Type-II VMMs, because of two reasons: a) the switching between the guest and the host VM for device driver invocation, and, b) I/O virtualization operations required to transfer packets between the guest and the host address spaces. We present a detailed analysis of the virtualization overheads in the Type-II I/O architecture, and we present three solutions which explore the performance that can be achieved while performing network virtualization at three different levels: in the host OS, in the VMM, and in the NIC hardware. Our first solution consists of a set of packet aggregation optimizations that explores the performance achievable while retaining the Type-II I/O architecture in the Xen VMM. This solution retains the core functionality of I/O virtualization, including device driver execution, in the Xen 'driver domain'. With this set of optimizations, we achieve an improvement by a factor of two to four in the networking performance of Xen guest domains. In our second solution, we move the task of I/O virtualization and device driver execution from the host OS to the Xen hypervisor. We propose a new I/O virtualization architecture, called the TwinDrivers framework, which combines the performance advantages of Type-I VMMs with the safety and software engineering benefits of Type-II VMMs. (In a Type-I VMM, the device driver executes directly in the hypervisor, and gives much better performance than a Type-II VMM). The TwinDrivers architecture results in another factor of two improvements in networking performance for Xen guest domains. Finally, in our third solution, we describe a hardware based approach to network virtualization, in which we move the task of network virtualization into the network interface card (NIC). We develop a specialized network interface (CDNA) which allows guest operating systems running in VMs to directly access a private, virtual context on the NIC for network I/O, bypassing the host OS entirely. This approach also yields performance benefits similar to the TwinDrivers software-only approach. Overall, our solutions help significantly bridge the gap between the network performance in a virtualized environment and a native environment, eventually achieving network performance in a virtual machine within 70% of the native performance.

EPFL2009

Chargement

EPFL2009