Tim Wilkinson, Tom Stiemerling, Peter E. Osmon, Ashley Saulsbury, and Paul Kelly. Angel: A proposed multiprocessor operating system kernel. In European Workshop on Parallel Computing, pages 316--319, Barcelona, Spain, 1992.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....in its own portable format: it compiles them to native code during loading and executes the native code directly. The advantage of Juice is that its portable format is faster to decode and easier to compile than Java s bytecode format. 6.3. 2 Single Address Space Systems Some operating systems [18, 44, 66, 86] decouple the notions of virtual address space and protection domain. Instead, they exploit a single address space for all processes. Placing di#erent processes in di#erent protection domains allows the system to control which pages are accessible to a given process. This control is enforced using ....

....They are therefore not susceptible to sharing attacks. However, because a type safe language is not used, memory protection must be used when untrusted threads access a shared segment, which is not required when di#erent Ka#eOS processes access shared kernel objects. 132 Systems such as Angel [86], Mungi [44] or Opal [18] implement access to secondary storage by allowing shared objects to be made persistent. As a consequence, such systems have to manage the secondary storage resources used. This problem is very similar to the problem of managing shared objects in Ka#eOS. Angel used a form ....

Wilkinson, T., Stiemerling, T., Gull, A., Whitcroft, A., Osmon, P., Saulsbury, A., and Kelly, P. Angel: a proposed multiprocessor operating system kernel. In Proceedings of the European Workshop on Parallel Computing (Barcelona, Spain, 1992), pp. 316--319.

....may be avoided by either synonym prevention, synonym avoidance or synonym detection [8] Physical address K A B Virtual address Virtual address Figure 2.14: A synonym example. Synonyms can be prevented by either using segments for sharing or by single address space operating systems (SASOSes) [49]. Both segments and SASOSes prevent synonyms by having the address that is used in the cache lookup belong to a single global virtual address space. Architectures with segments use some bits in the virtual address generated by the processor to index a set of segment registers which then provide an ....

....the cache lookup belong to a single global virtual address space. Architectures with segments use some bits in the virtual address generated by the processor to index a set of segment registers which then provide an address in the global virtual address space to the cache, see Figure 2.15. SASOSes [49] have a single global virtual address space visible directly to all processes. Sharing is achieved through the same virtual address, therefore no synonyms are necessary in a SASOS. A simple way to avoid synonyms is not to cache synonyms unless they are readonly. This will degrade performance ....

Tim Wilkinson, Tom Stiemerling, Peter E. Osmon, Ashley Saulsbury, and Paul Kelly. Angel: A proposed multiprocessor operating system kernel. In European Workshop on Parallel Computing, pages 316--319, Barcelona, Spain, 1992.

....represented on the Figure 3.1. I also presume a software support of uniform shared memory, where the task migration can be performed in O(1) time. This feature has been implemented for example in the distributed operating system Angel supporting single address space. For more details see [4] [5], 7] I assume that interprocess communication is negligible and processes are independent from each other. 32 MEMORY SHARED Scheduler1 Scheduler2 Microkernel Microkernel Scheduler3 Microkernel User1 USER TASK 2 User2 User3 CPU 1 CPU 2 CPU 3 MIGRATING USER TASK code and data ....

....easy task migration, necessary for my algorithm proposal. Available candidates (for example PVM system) supporting a communication via message passing were not convenient. 45 Among operating systems supporting shared memory, I have chosen OS Angel realising single address space (see [4] [5], 7] but this system, is still under the development, so my measurement would not be ready till the thesis deadline. For this reasons I have decided to develop a simple environment simulating distributed system in the features necessary for trying out my algorithm. The simulations has been ....

T.Wilkinson, T.Stiemerling, P. Osmon, A.Saulsbury, P. Kelly. Angel: a proposed multiprocessor operating system kernel. Tech. Report, City University, 1992

....either accessing a local copy of the memory or by performing a remote access. This mechanism eliminates the translation of addresses above the virtual memory layer when references are exchanged between nodes. Most distributed shared memory systems that are not implemented as SAS operating systems [18], 19] 20] 21] do not map the complete memory of all nodes into a single virtual address space. They rather provide means to map parts of memory of a remote node into the local memory of a node. This makes it necessary for Kaffemik to have an interface that supports this mapping of memory ....

T. J. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: A proposed multiprocessor operating system kernel," Tech. Rep. TCU/CS/

....they rely on the use of custom hardware in order to emulate a large address space on the processor architectures available at the time. The advent of 64 bit computer architectures, such as the HP PA, the MIPS R4000, and the DEC Alpha, has now made the single address space approach feasible [6 8]. A 64 bit address space is big enough to allow the unification of all data on all nodes of a distributed system of thousands of machines. In such a single address space operating system (SASOS) there is a single, system wide name for each object its virtual memory address. Sharing in such a ....

....Recent work In recent years there have been several projects investigating the design and benefits of SASOS. They have in common a 64 bit distributed persistent memory, which is implemented without the use of specialised hardware. The systems differ, however, in interesting ways. The Angel [6, 10] project was the first of these systems. The designers of Angel have studied fault tolerance issues [11] and have shown that, by making the distributed single address space fault tolerant, this reliability is automatically inherited by other software structures built on top. They have furthermore ....

T. Wilkinson, T. Stiemerling, P. E. Osmon, A. Saulsbury, and P. Kelly. Angel: A proposed multiprocessor operating system kernel. In European Workshop on Parallel Computing, pages 316--319, Barcelona, Spain, 1992.

....a single, shared address space, regardless of the real arrangement of memory. This requires remote memory references either to be compiled into messages or to be effected by messages at run time. So far, results have not suggested that this approach is scalable, but it is an ongoing research area [53, 138, 169, 201]. Annotated functional languages make the compiler s job easier by allowing programmers to provide extra information about suitable ways to partition the computation into pieces and place them [129] The same reduction rules apply, so that the communication and synchronization induced by this ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly. Angel: a proposed multiprocessor operating system kernel. In Proceedings of the European Workshops on Parallel Computing (EWPC'92), 23-24 March 1992, Barcelona , Spain, pages 316--319, 1992.

.... A Windowing system for Angel Alan Messer Systems Architecture Research Centre, City University, Northampton Square, London EC1V 0HB, UK April 16, 1997 Abstract This paper describes the Halo windowing system for the Angel [1, 2] operating system currently being developed at City University. The aim of this windowing system is to provide a clean parallel object oriented design utilising the unified resources in the single address space of Angel. Halo provides an object design for a basic window library which can then be ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: A Proposed Multiprocessor Operating System Kernel (Extended Abstract)," in European Workshop on Parallel Computing, March 1992.

....be changed as often this improves cache associativity; RPC can be implemented without explicit data copying thereby improving performance; and the DSM scheme becomes an integral part of the kernel. Thus Angel was born; it was designed around a single address space maintained by DSM techniques [8]. There are three very important features in the design of Angel: ffl minimalism. A micro kernel is provided which supplies only the most basic functionality any required services or additional functionality can be built above it. ffl separation. The separation of protection issues and ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: A Proposed Multiprocessor Operating System Kernel (Extended Abstract)," in European Workshop on Parallel Computing, March 1992.

No context found.

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly. "Angel: A Proposed Multiprocessor Operating System Kernel (Extended Abstract),". In European Workshop on Parallel Computing, March 1992.

....is contrary to the micro kernel philosophy though, and could create synchronisation problems within the region handling code. The DVSM implementation has led us on to investigate whether DVSM could be used as the basis for an operating system system based on a single coherent shared address space [17]. 12 Acknowledgements Topsy and Meshix were written and directed by Phil Winterbottom and Tim Wilkinson, and produced by Peter Osmon. Thanks to Paul Kelly for pointing out that synchronous invalidation was necessary for correct operation, and Martin Cripps for suggesting the correct solution to ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: a proposed multiprocessor operating system," in European Workshops on Parallel Computing 92, March 1992.

....due to the additional remote procedure calls (RPCs) between micro kernel and external servers. Whilst this allows greater flexibility and easy extensibility, the results so far have been slower and more complex than the original monolithic systems they tried to simplify. The Angel operating system [4] was developed as an experimental system to examine the various concepts needed in the construction of large scale parallel and distributed system. Part of this work has allowed us to demonstrate that the traditional compromise between performance, flexibility and security need not apply. In the ....

....an overview of the Angel system. We then describe how it implements the mechanisms to allow simple extension of the system without compromising security and demonstrate how these operate with a simple example. We finish with an analysis of the system and conclusions. 2 Angel The Angel system [4, 5] is an experimental single address space operating system (SASOS) being developed at City University. Angel s design builds on the established micro kernel approach, retaining the flexibility of external servers, but addressing the problems of service and resource complexity as well as the ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: A Proposed Multiprocessor Operating System Kernel (Extended Abstract)," in European Workshop on Parallel Computing, March 1992.

....and capabilities. Then we describe how the sub components of Angel, the micro kernel and system services, are structured and interact to provide this model. Finally we present a plan for further work, and summarise the main points of the paper. An extended abstract of this paper has been published [11]. 2 Lessons from earlier work A DSM system has been prototyped on Meshix as an external pager (using a similar approach to the implementation on Mach [12] The following observations have been made during this work, and also concerning Meshix in general: ffl Monolithic Unix implementations can ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: a proposed multiprocessor operating system," in European Workshops on Parallel Computing 92, March 1992.

....memory system, while in others the necessary kernel support for DVSM must be added by hand. Systems in which the DVSM management has been incorporated into the operating system kernel, and is the basis for all virtual memory management, are also being researched. Examples are Clouds and Angel [6]. Such systems should have higher performance than server implementations due to the reduced message and domain crossing overheads. There are also hardware DVSM systems in which hardware support is provided for DVSM management. Examples are PLUS, DASH and MemNet. Such systems generally provide ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: a proposed multiprocessor operating system," in European Workshops on Parallel Computing 92, March 1992.

....and architecture. Resource unification provides an approach to achieving this goal. This paper examines the reasoning behind resource unification, and why the new generation of processors and networks make it feasible. An overview of the approach is then given, followed by our implementation Angel [11], a Single Address Space Architecture (SASA) The benefits this gives are outlined as well as the problems introduced. 2 Shortcomingsof Meshix and other Microkernels The original goal of Meshix and the Topsy architecture was to produce a scalable, parallel UNIX multicomputer with a simple, ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: A Proposed Multiprocessor Operating System Kernel (Extended Abstract)," in European Workshop on Parallel Computing, March 1992.

....are not reachable by incremental development of Topsy. Therefore, whilst the Unix work will continue, the group is also investigating the design of a new distributed operating system which will provide and an efficient environment for shared memory parallel programming. The project, named Angel [30], proposes a single address space distributed operating system. This greatly simplifies the caching of code, migration of data and coherency of distributed data structures. Angel will support this single address space on a multiprocessor machine which contains both shared and distributed memory. ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: a proposed multiprocessor operating system," Tech. Rep. (forthcoming), City University Computer Science Department, October 1991.

....larger communication overheads due to the additional remote procedure calls (RPCs) between micro kernel and external servers. While more flexible, this can result in a system which is slower and more complicated than the original monolithic system it tries to simplify. The Angel operating system [4] was developed to experiment with various concepts needed in the construction of large scale parallel systems. As part of this work, it was necessary to show that the advantages of an extensible operating system need not be a compromise of performance, flexibility and security. To this end, the ....

....of this work, section 3 describes the problems associated with providing efficient and secure client server kernel interaction, section 4 describes the adopted solution, and section 5 describes how this solution operates in practice and an analysis of its costs. 2 Angel overview The Angel system [4, 5] is an experimental single address space operating system (SASOS) being developed at City University 1 . Angel s design attempts to build on the established micro kernel approach, retaining the flexibility of external servers, but addresses the problems of service and resource complexity and the ....

T. Wilkinson, T. Stiemerling, P. Osmon, A. Saulsbury, and P. Kelly, "Angel: A Proposed Multiprocessor Operating System Kernel (Extended Abstract)," in European Workshop on Parallel Computing, March 1992.

No context found.

Tim Wilkinson, Tom Stiemerling, Peter E. Osmon, Ashley Saulsbury, and Paul Kelly. Angel: A proposed multiprocessor operating system kernel. In European Workshop on Parallel Computing, pages 316--319, Barcelona, Spain, 1992.

No context found.

Tim Wilkinson, Tom Stiemerling, Peter E. Osmon, Ashley Saulsbury, and Paul Kelly. Angel: A proposed multiprocessor operating system kernel. In European Workshop on Parallel Computing, pages 316--319, Barcelona, Spain, 1992.

No context found.

T. Wilkinson, T. Stiemerling, P. Osmon, A Saulsbury, and P. Kelly. Angel: A proposed multiprocessor operating system kernel. Technical Report TCU/CS/1992/10, Department of Computer Science, City University, London, 1992.

No context found.

T. Wilkinson, T. Stiemerling, P. E. Osmon, A. Saulsbury, and P. Kelly. Angel: A proposed multiprocessor operating system kernel. In European Workshop on Parallel Computing, pages 316--319, Barcelona, Spain, 1992.

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