B. W. Lampson and R. F. Sproull, "An Open Operating System for a Single-User Machine," Proc 7th Symposium on Operating Systems Principles 9-17, ACM, December 1979.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....delay, it will occasionally expire when there was no transmission error. Protocols which make use of optimization timers are designed to be resistant to the possibility that the timer expires when no error has occurred. A common technique is to use the optimization timer as no more than a hint [15]. In the preceding sections, we have shown that there is a need for two kinds of timers in layered protocol implementations. Death timers are used to avoid a deadlock situation whereby a process hangs on network input forever, locking up system resources that are needed by other processes. ....

B. Lampson, R. Sproull. An Open Operating System for a Single-User Machine. Proceedings of the Seventh Symposium on Operating Systems Principles , ACM Order # 534790 (December 1979). 115

....for a model operating system. Further experience is needed to see if a low level kernel interface is indeed the panacea that can cure current operating system troubles. The open operating system for a single user machine is motived by similar observations as the ones that motivate the exokernel [16]. However, the approach taken to extensibility taken is different. The exokernel s main task is secure multiplexing, while in the open operating system protection is not an issue at all, since it relies on the fact it is designed for a singleuser machine. In addition, the exokernel attempts to ....

B.W. Lampson and R.F. Sproull. An open operating system for a single-user machine. Proceedings of the Seventh ACM Symposium on Operating Systems Principles, pages 98--105, 1979.

....important properties of the Pilot file system is robustness. This is achieved primarily through the use of reconstructable maps. Many previous systems have demonstrated the value of a file scavenger, a utility program which can repair a damaged file system, often on a more or less ad hoc basis [5, 12, 14, 21]. In Pilot, the scavenger is given first class citizenship, in the sense that the file structures were all designed from the beginning with the scavenger in mind. Each file page is self identifying by virtue of its label, written as a separate physical record adjacent to the one holding the actual ....

Lampson, B.W., and Sproull, R.F. An open operating system for a single user machine. Presented at the ACM 7th Symp. Operating System Principles (Operating Syst. Rev. 13, 5), Dec. 1979, pp. 98--105.

....problems are mitigated by automatically limiting the number of versions that are kept. Each local name has a property called its keep, a numeric value that specifies the number of versions of the local name to keep around. Automatically processed keeps first appeared in the Alto operating system [10], although the feature got little use. In CFS, whenever a local name is created its keep is inherited from the highest existing version or set from an argument to the operation doing the creation. Keep processing occurs when creating a new version of a local name. In this case CFS will enumerate ....

Lampson, B.W. and Sproull, R.F., "An Open Operating System for a Single-User Machine," Proc. 7th ACM SIGOPS SOSP, Dec 1979, pp. 98--105.

.... Implementation levels of different services (kernel , user or application level ) ffl Implementation languages: Modula 3 or Java or C 6 Related Work The basic design approach uses the end to end argument [SRC84] The end to end argument has been used for designing operating and file systems [LS79, EKJ95] Other key projects that have influenced this design are: Exokernel Virtual disk [dJKH93] NASD file systems [GNA 97] xFS [ADN 96] Frangipani [TML97] HFS [Kri94] Forum [GSSW95] and Windows NTFS [Nag97, RvIG97] 7 Summary Traditional file systems suffer from the following ....

B. Lampson and R. Sproull. An Open Operating System for a Single-user Machine. ACM Operating Systems Rev., 11(5):98--105, December 1979.

....systems but, importantly, the fact that they are unprivileged will enable them to evolve more readily than traditional systems. 1. 1 Relation to other OS structures There is a large literature on extensible operating systems, starting with the classic rationales by Lampson and Brinch Hansen [41, 53, 54]. Previous approaches to extensibility can be coarsely classified in to three groups: better microkernels, virtual machines, and downloading untrusted code into the kernel. We discuss each in turn and then relate exokernels to recent work in extensible operating systems. The exokernel differs from ....

....(one to fetch the capability and one to fetch the block) While caching can mitigate this problem to a degree, we are nervous about its overhead on disk intensive workloads. An alternative approach is to co locate capabilities with disk blocks by placing them immediately before a disk block s data [54]. Unfortunately, on common hardware, reserving space for a capability would prevent blocks from being multiples of the page size, adding overhead and complexity to disk operations. Self descriptive meta data. Our first serious attempt at efficient disk multiplexing provided a means for each ....

B.W. Lampson and R.F. Sproull. An open operating system for a single-user machine. Proceedings of the Seventh ACM Symposium on Operating Systems Principles, pages 98--105, December 1979.

....was built on hardware, rather than an existing operating system, 32 the mechanisms and implementations are not directly comparable to those in this document. But we have built on their idea of encapsulating resources into fine grained objects. 3.3. 2 Alto Single User System Lampson and Sproull [Lampson, 79] implemented an open operating system for the Alto personal computer. Like DOS (which was developed later) their system did not provide preemptive multitasking or protection. However, it used abstract objects with multiple implementations to provide disciplined flexibility and treated ....

B. W. Lampson & R. F. Sproull, An Open Operating System for a Single-User Machine, Proc. 7th Symposium on Operating Systems Principles, ACM, Operating Systems Review, 13(5), pp. 98-105.

....TCB primitives should be made atomic (if any) or which TCB primitives should only help detect insecure states after crashes (but not be atomic) belongs to the system designers. An example of a file system design allowing the detection of inconsistent states by a scavenging process is provided in [22]. The scavenging process recovers files whose representation is intact, and deletes files whose representations become inconsistent after crashes. To a large extent, the UNIX system calls are designed to ensure that the fsck program can detect a variety of file system inconsistencies after ....

Lampson, B. W., Robert F. Sproull, "An Open Operating System for a Single-User Machine," in Proceedings of the Seventh Symposium on Operating Systems Principles, Pacific Grove, California, December 1979, pp. 98-105.

....quick access to an answer that is likely to be correct can greatly improve efficiency in the normal case, and the cost of dealing with incorrect answers when they do occur is not too high. Lampson [Lam83] describes this kind of mechanism as hints, and describes several systems that use such hints [LS79, MW77, Smi81]. More recently, hints have been used in mobile systems to find more direct routes to the current location of a mobile device [JP96, CP96] 1.1 Related Work Though ours is the first work to study probabilistic quorum systems as such, the use of replicated variables to give probably correct ....

B. Lampson and R. Sproul. An open operating system for a single-user machine. Operating Systems Review, 13(5):98-- 105, 1979.

....anticipate the client s requirements for an esoteric feature will probably miss the target slightly and the client will end up reimplementing that feature anyway. We are indebted to M. Satyanarayanan for pointing out this example. Lampson, in his arguments supporting the open operating system, [9] uses an argument similar to the end to end argument as a justification. Lampson argues against making any function a permanent fixture of lower level modules; the function may be provided by a lower level module but it should always be replaceable by an application s special version of the ....

Lampson, B.W., and Sproull, R.F. An open operating system for a single-user machine. Proc. Seventh Symposium on Operating Systems Principles, Operating Systems Review 13, Special issue (December, 1979), pp.98-105.

....21, 25] 2.2 Exokernels: An End to End Argument The essential observation about core abstractions in traditional operating systems is that they are overly general. Traditional operating systems attempt to provide all the features needed by all applications. As previously noted by Lampson et al. [28], Anderson et al. 3] and Massalin [31] general purpose implementations of core abstractions force applications that do not need a given feature to pay substantial overhead costs. This longstanding problem has become more important with explosive improvements in raw hardware performance and ....

....be used by the window manager to set up a binding between an application and a portion of the frame buffer. The application can access the frame buffer hardware directly because the hardware checks the ownership tag when I O takes place. Similarly, the label feature of the Xerox Alto disk device [28] could be used by an exokernel to cheaply implement secure bindings for individual disk blocks. Multiplexing the Network If there is no hardware capability support that can be used to efficiently multiplex a device, secure bindings can be implemented by the exokernel. We have already seen that ....

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B.W. Lampson and R.F. Sproull. An open operating system for a single-user machine. Proceedings of the Seventh ACM Symposium on Operating Systems Principles, pages 98--105, 1979.

....2.1 The Cost of Fixed High Level Abstractions The essential observation about abstractions in traditional operating systems is that they are overly general. Traditional operating systems attempt to provide all the features needed by all applications. As previously noted by Lampson and Sproul [32], Anderson et al. 4] and Massalin and Pu [36] general purpose implementations of abstractions force applications that do not need a given feature to pay substantial overhead costs. This longstanding problem has becomemore important with explosive improvements in raw hardware performance and ....

....of the design grew. By constructing a domain specific scheduler, these applications can now effectively and accurately schedule subprocesses, greatly improving fault isolation and independence. 8 Related work Many early operating system papers discussed the need for extendible, flexible kernels [32, 42]. Lampson s description of CALTSS [31] and Brinch Hansen s microkernel paper [24] are two classic rationales. Hydra was the most ambitious early system to have the separation of kernel policy and mechanism as one of its central tenets [55] An exokernel takes the elimination of policy one step ....

B.W. Lampson and R.F. Sproull. An open operating system for a single-user machine. Proceedings of the Seventh ACM Symposium on Operating Systems Principles, pages 98--105, December 1979.

....significantly better than Ultrix on microbenchmarks. While the paper provided evidence that the exokernel approach was promising, it left many questions unanswered. There is a large literature on extensible operating systems, starting with the classic rationales by Lampson and Brinch Hansen [19, 25, 26]. Previous approaches to extensibility can be coarsely classified in three groups: better microkernels, virtual machines, and downloading untrusted code into the kernel. We discuss each in turn. The principal goal of an exokernel giving applications control is orthogonal to the question of ....

....(one to fetch the capability and one to fetch the block) While caching can mitigate this problem to a degree, we are nervous about its overhead on disk intensive workloads. An alternative approach is to co locate capabilities with disk blocks by placing them immediately before a disk block s data [26]. Unfortunately, on common hardware, reserving space for a capability would prevent blocks from being multiples of the page size, adding overhead and complexity to disk operations. Self descriptive metadata. Our first serious attempt at efficient disk multiplexing provided a means for each ....

B.W. Lampson and R.F. Sproull. An open operating system for a single-user machine. Proceedings of the Seventh ACM Symposium on Operating Systems Principles, pages 98--105, December 1979.

....is learning how to make better implementations. But since research may well fail, others mustn t depend on its success. Algol 60 was not only an improvement on its predecessors, but also on nearly all its successors. C. Hoare) Examples of offering too much are legion. The Alto operating system [29] has an ordinary read write n bytes interface to files, and was extended for Interlisp D [7] with an ordinary paging system that stores each virtual page on a dedicated disk page. Both have small implementations (about 900 lines of code for files, 500 for paging) and are fast (a page fault takes ....

....is multiplexing a resource, and this necessarily has some cost. But it should be possible to deliver all or nearly all of it to a single client with only slight loss of performance. For example, the Alto disk hardware [53] can transfer a full cylinder at disk speed. The basic file system [29] can transfer successive file pages to client memory at full disk speed, with time for the client to do some computing on each sector; thus with a few sectors of buffering the entire disk can be scanned at disk speed. This facility has been used to write a variety of applications, ranging from a ....

[Article contains additional citation context not shown here]

Lampson, B.W. and Sproull, R.S. An open operating system for a single-user machine. Operating Systems Review 13, 5, Dec. 1979, pp 98-105.

....system has in common only the file system format on the disk and the network protocols. These were established by the BCPL operating system and did not change after 1976; they constitute the interface between the various programming environments. Operating systems The first Alto operating system [29], usually called the OS, is derived from Stoy and Strachey s 056 [47] It provides a disk file and directory system, a keyboard handler, a teletype simulator for the screen, a standard stream abstraction for input output, a program loader, and a free storage allocator. There is no provision for ....

B. W. Lampson and R. F. Sproull. An open operating system for a single-user machine. ACM Operating Systems Review, 13(5), November 1979.

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B. W. Lampson and R. F. Sproull, "An Open Operating System for a Single-User Machine," Proc 7th Symposium on Operating Systems Principles 9-17, ACM, December 1979.

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