Xen Research Papers - Academia.edu (original) (raw)

The Virtualization technology [VT] plays vital role in efficient utilization of computer resources in any organization and is the basic concept used in cloud computing. Main advantage of using VT is that we need less Information technology [IT] infrastructure resources. We prove here that live migration feature provided by XEN hypervisor is quiet useful. It increases availability of application and is transparency to user. We executes live migrate command of XEN, the VM runs on source host till all memory pages are transferred to destination host (pre-copy). We can also observe that during and after migration VM preserves its IP address. The main use of virtualization technology is server consolidation i.e. to run multiple server operating systems (VMs) on single physical hardware. By running multiple VMs on single physical machine we can reduce expenditure on IT hardware.

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- Virtualization, Live Migration, Xen, Hypervisor

Cloud computing is a way of delivering computing power and other resources on pay-per-use basis. Cloud can be of type public or private depending on the type of network is used for delivering the services. A cloud service comes under various categories depending on the level of resource that is Infrastructure, platform or service. Many cloud computing services are available today to fulfill the user needs and demands. Cloud computing has also attracted many researchers for experimentation for new or existing services. Before deployment of actual cloud experimentation can be done with respect to available tools to perform testing and setting up the benchmarks. An analysis by considering various parameters of such tools is presented to provide guidelines about their working with cloud.

- by Rizwana Shaikh
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- Computer Science, Tools, Xen, Simulation Tools
- by Hoa Nhat
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- Computer Engineering, Virtualization, Live Migration, Xen

Eucalyptus is an open-source software platform used to create a virtual IT infrastructure with all facilities like storage, network and security as available in real scenarios in a computer system so that researchers and cloud system developers can test their software with least amount of expenditure. Xen is the underlying Virtual Machine Monitor better known as Hypervisor used to simulate the various virtual machines (hardware or software) to work upon. The main aim is to generate a pool of resources or a ‘cloud’ using the above tools and manage them effectively. less

- by Kaustav Choudhury
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- Network Security, Ubuntu, Cloud Computing, Open Source

Understanding workload performance and resource utilization under full system virtualization is challenging because of the additional Virtual Machine Monitor layer, the sharing of resources across the many virtual machine operating systems, and the alternative mechanism by which several system facilities, such as I/O and interrupts, are handled. New pro ling, characterization, and modeling methodologies are required to shed light on the nature of system behavior under full system virtualization, including the behavior of hardware, system software, and guest software. We demonstrate that such methods are possible through synchronous and vertical data collection and analysis. The resulting pro ling data, characterizations and models enable a multitude of analyses which can better explain the complex transformations in hardware and software interaction brought about by the introduction of system virtualization. Such analyses aid the understanding of virtualized system performance and guide the future development of hardware and software virtualization solutions.

- by Hussam Mousa
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- Virtualization, Benchmarking, VMWare, Performance Counters
- by Tácio Andrade
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- Virtualization, Xen

Purpose To assess the efficacy and safety of the XEN Gel Stent in patients with primary open-angle glaucoma. Materials and methods Twenty eyes of 17 patients (6 males, 11 females) with primary open-angle glaucoma were implanted with XEN Gel Stent. The following data were ascertained in each participant at baseline and at 1, 3, 6, 9 and 12 months following implanting procedure: intraocular pressure, number of anti-glaucoma medications, retinal sensitivity (PS 24/2 w/w), pattern electroretinogram (ISCEV standard), as well as the number of complications. Results The mean intraocular pressure reduction in a 1-year follow-up was 18% (21.56 vs. 17.69 mmHg, p \ 0.001). The mean number of anti-glaucoma medications was reduced from 3.2 to 1.6 (p = 0.001). The PERG parameters at baseline and at 12 months postoperatively included a stable amplitude of P50 (2.55 lV vs. 2.65 lV, p = 0.024) and N95 (3.45 lV vs. 3.38 lV, p = ns) waves. The delta N95 and delta P50 amplitudes remained stable over the follow-up period (p = ns). The mean deviation (MD) of PS 24/2 was-6.54 dB vs.-8.43 dB, p = ns, whereas the pattern standard deviation (PSD) was 6.18 dB vs. 6.91 dB, p = ns. Transient hypotony within the first postoperative week occurred in 18 eyes (90%), whereas hyphema occurred in two eyes (10%). Needle revision of a filtration bleb was performed in five eyes (25%). Conclusions The XEN Gel Stent enables significant reduction in intraocular pressure with very low complication rates. It ensures a stabilization of the retinal function as established with the PERG.

- by Michal Post and +1
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- Ophthalmology, Electrophysiology, Xen, Glaucoma Surgery

If the operating system could be specialized for every application, many applications would run faster. For example, Java virtual machines (JVMs) provide their own threading model and memory protection, so general-purpose operating system implementations of these abstractions are redundant. However, traditional means of transforming existing systems into specialized systems are difficult to adopt because they require replacing the entire operating system. This paper describes Libra, an execution environment specialized for IBM's J9 JVM. Libra does not replace the entire operating system. Instead, Libra and J9 form a single statically-linked image that runs in a hypervisor partition. Libra provides the services necessary to achieve good performance for the Java workloads of interest but relies on an instance of Linux in another hypervisor partition to provide a networking stack, a filesystem, and other services. The expense of remote calls is offset by the fact that Libra's...

- by Eric Van Hensbergen
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- OPERATING SYSTEM, Search Engine, Xen, Experimentation

Virtualization technology is currently widely used due to its benefits on high resource utilization, flexible manageability and powerful system security. However, its use for high performance computing (HPC) is still not popular due to the unclearness of the virtualization overheads. It's worthy to evaluate the virtualization cost and to find the performance bottleneck when running HPC applications in virtual cluster. We first evaluate the basic performance overheads due to virtualization. Then we create a 16-node virtual cluster and perform a performance evaluation for both para-virtualization and full virtualization. After that, we evaluate the MPI (Message Passing Interface) scalability to investigate the impact of MPI and network communication between virtual machines. In addition to the macro assessment, we use the Oprofile/Xenoprof to investigate the architecture characterization like CPU cycle, L2 cache misses, DTLB misses and ITLB misses which is an auxiliary explanation to the performance bottleneck. Experimental results indicate that performance overheads of virtualization are acceptable for HPC, para-virtualization is very suitable for HPC due to the high virtualization efficiency and efficient inter-domain communication. Finally, we use the non-linear regression modeling technology to present a performance model for network latency and bandwidth to predict the performance in virtual cluster environment.

- by Kejiang Ye
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- Performance Studies, Virtual Machines, Performance Modeling, Xen

- by Michal Post
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- Ophthalmology, Electrophysiology, Xen, Clinical Sciences

Xen is one of the most popular open-source virtualization software’s. It supports the two leading virtualization approaches, Full-Virtualization (FV) and Para-Virtualization (PV).Searching the public resources for performance comparison between these two approaches shows that PV performs the best. But most of the answers are theoretical, based on the implementation of both. For instance, Xen community states the following: “PV delivers higher performance than full virtualization because the operating system and hypervisor work together more efficiently, without the overhead imposed by the emulation of the system's resources”.This paper presents an experimental work based on tests and scenarios to compare the quantitative performance between PV and FV. The quantitative results show indeed the predicted performance gap.

- by Martin Timmerman
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- Engineering, Xen, Para Virtualization