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216
Exokernel: An Operating System Architecture for Application-Level Resource Management
, 1995
"... We describe an operating system architecture that securely multiplexes machine resources while permitting an unprecedented degree of application-specific customization of traditional operating system abstractions. By abstracting physical hardware resources, traditional operating systems have signifi ..."
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Cited by 732 (24 self)
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We describe an operating system architecture that securely multiplexes machine resources while permitting an unprecedented degree of application-specific customization of traditional operating system abstractions. By abstracting physical hardware resources, traditional operating systems have significantly limited the performance, flexibility, and functionality of applications. The exokernel architecture removes these limitations by allowing untrusted software to implement traditional operating system abstractions entirely at application-level. We have implemented a prototype exokernel-based system that includes Aegis, an exokernel, and ExOS, an untrusted application-level operating system. Aegis defines the low-level interface to machine resources. Applications can allocate and use machine resources, efficiently handle events, and participate in resource revocation. Measurements show that most primitive Aegis operations are 10–100 times faster than Ultrix,a mature monolithic UNIX operating system. ExOS implements processes, virtual memory, and inter-process communication abstractions entirely within a library. Measurements show that ExOS’s application-level virtual memory and IPC primitives are 5–50 times faster than Ultrix’s primitives. These results demonstrate that the exokernel operating system design is practical and offers an excellent combination of performance and flexibility. 1
A Secure Environment for Untrusted Helper Applications -- Confining the Wily Hacker
"... Many popular programs, such as Netscape, use untrusted helper applications to process data from the network. Unfortunately, the unauthenticated network data they interpret could well have been created by an adversary, and the helper applications are usually too complex to be bug-free. This raises si ..."
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Cited by 462 (7 self)
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Many popular programs, such as Netscape, use untrusted helper applications to process data from the network. Unfortunately, the unauthenticated network data they interpret could well have been created by an adversary, and the helper applications are usually too complex to be bug-free. This raises significant security concerns. Therefore, it is desirable to create a secure environment to contain untrusted helper applications. We propose to reduce therisk of a security breachby restricting the program's access to the operating system. In particular, we intercept and filter dangerous system calls via the Solaris process tracing facility. This enabled us to build a simple, clean, user-mode implementation of as ecure environment for untrusted helper applications. Our implementation has negligible performance impact, and can protect pre-existing applications.
Informed Prefetching and Caching
- In Proceedings of the Fifteenth ACM Symposium on Operating Systems Principles
, 1995
"... The underutilization of disk parallelism and file cache buffers by traditional file systems induces I/O stall time that degrades the performance of modern microprocessor-based systems. In this paper, we present aggressive mechanisms that tailor file system resource management to the needs of I/O-int ..."
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Cited by 402 (10 self)
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The underutilization of disk parallelism and file cache buffers by traditional file systems induces I/O stall time that degrades the performance of modern microprocessor-based systems. In this paper, we present aggressive mechanisms that tailor file system resource management to the needs of I/O-intensive applications. In particular, we show how to use application-disclosed access patterns (hints) to expose and exploit I/O parallelism and to allocate dynamically file buffers among three competing demands: prefetching hinted blocks, caching hinted blocks for reuse, and caching recently used data for unhinted accesses. Our approach estimates the impact of alternative buffer allocations on application execution time and applies a cost-benefit analysis to allocate buffers where they will have the greatest impact. We implemented informed prefetching and caching in DEC’s OSF/1 operating system and measured its performance on a 150 MHz Alpha equipped with 15 disks running a range of applications including text search, 3D scientific visualization, relational database queries, speech recognition, and computational chemistry. Informed prefetching reduces the execution time of the first four of these applications by 20 % to 87%. Informed caching reduces the execution time of the fifth application by up to 30%.
Lightweight remote procedure call
- ACM Transactions on Computer Systems
, 1990
"... Lightweight Remote Procedure Call (LRPC) is a communication facility designed and optimized for communication between protection domains on the same machine. In contemporary small-kernel operating systems, existing RPC systems incur an unnecessarily high cost when used for the type of communication ..."
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Cited by 292 (26 self)
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Lightweight Remote Procedure Call (LRPC) is a communication facility designed and optimized for communication between protection domains on the same machine. In contemporary small-kernel operating systems, existing RPC systems incur an unnecessarily high cost when used for the type of communication that predominates-between protection domains on the same machine. This cost leads system designers to coalesce weakly related subsystems into the same protection domain, trading safety for performance. By reducing the overhead of same-machine communication, LRPC encourages both safety and performance. LRPC combines the control transfer and communication model of capability systems with the programming semantics and large-grained protection model of RPC. LRPC achieves a factor-of-three performance improvement over more traditional approaches based on independent threads exchanging messages, reducing the cost of same-machine communication to nearly the lower bound imposed by conventional hardware. LRPC has been integrated into the Taos operating system of the DEC SRC Firefly multiprocessor workstation.
The Amber System: Parallel Programming on a Network of Multiprocessors
- In Proceedings of the 12th ACM Symposium on Operating Systems Principles
, 1989
"... Microprocessor-based shared-memory multiprocessors are becoming widely available and promise to provide cost-effective high-performance computing. This paper describes a programming system called Amber which permits a single application program to use a homogeneous network of multiprocessors in a un ..."
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Cited by 231 (15 self)
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Microprocessor-based shared-memory multiprocessors are becoming widely available and promise to provide cost-effective high-performance computing. This paper describes a programming system called Amber which permits a single application program to use a homogeneous network of multiprocessors in a uniform way, making the network appear to the application as an integrated, non-uniform memory access, shared-memory multiprocessor. This simplifies the development of applications and allows compute-intensive parallel programs to effectively harness the potential of multiple nodes. Amber programs are written using an object-oriented subset of the C++ programming language, supplemented with primitives for managing concurrency and distribution. Amber provides a network-wide shared-object virtual memory in which coherence is provided by hardware means for locally-executing threads, and by software means for remote accesses. Amber runs on top of the Topaz operating system on a network of DEC SRC ...
Building Secure and Reliable Network Applications
, 1996
"... ly, the remote procedure call problem, which an RPC protocol undertakes to solve, consists of emulating LPC using message passing. LPC has a number of "properties" -- a single procedure invocation results in exactly one execution of the procedure body, the result returned is reliably deliv ..."
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Cited by 230 (16 self)
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ly, the remote procedure call problem, which an RPC protocol undertakes to solve, consists of emulating LPC using message passing. LPC has a number of "properties" -- a single procedure invocation results in exactly one execution of the procedure body, the result returned is reliably delivered to the invoker, and exceptions are raised if (and only if) an error occurs. Given a completely reliable communication environment, which never loses, duplicates, or reorders messages, and given client and server processes that never fail, RPC would be trivial to solve. The sender would merely package the invocation into one or more messages, and transmit these to the server. The server would unpack the data into local variables, perform the desired operation, and send back the result (or an indication of any exception that occurred) in a reply message. The challenge, then, is created by failures. Were it not for the possibility of process and machine crashes, an RPC protocol capable of overcomi...
Exploiting Weak Connectivity for Mobile File Access
, 1995
"... Weak connectivity, in the form of intermittent, low-bandwidth, or expensive networks is a fact of life in mobile computing. In this paper, we describe how the Coda File System has evolved to exploit such networks. The underlying theme of this evolution has been the systematic introduction of adaptiv ..."
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Cited by 197 (22 self)
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Weak connectivity, in the form of intermittent, low-bandwidth, or expensive networks is a fact of life in mobile computing. In this paper, we describe how the Coda File System has evolved to exploit such networks. The underlying theme of this evolution has been the systematic introduction of adaptivity to eliminate hidden assumptions about strong connectivity. Many aspects of the system, including communication, cache validation, update propagation and cache miss handling have been modified. As a result, Coda is able to provide good performance even when network bandwidth varies over four orders of magnitude -- from modem speeds to LAN speeds.
Lightweight recoverable virtual memory
- ACM Transactions on Computer Systems
, 1994
"... Recoverable virtual memory refers to regions of a virtual This combination of circumstances is most likely to be found in situations involving the meta-data of storage address space on which transactional guarantees are repositories. Thus RVM can benefit a wide range of offered. This paper describes ..."
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Cited by 122 (10 self)
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Recoverable virtual memory refers to regions of a virtual This combination of circumstances is most likely to be found in situations involving the meta-data of storage address space on which transactional guarantees are repositories. Thus RVM can benefit a wide range of offered. This paper describes RVM, an efficient, portable, applications from distributed file systems and databases, to and easily used implementation of recoverable virtual object-oriented repositories, CAD tools, and CASE tools. memory for Unix environments. A unique characteristic RVM can also provide runtime support for persistent of RVM is that it allows independent control over the programming languages. Since RVM allows independent transactional properties of atomicity, permanence, and serializability. This leads to considerable flexibility in the use of RVM, potentially enlarging the range of applications than can benefit from transactions. It also control over the basic transactional properties of atomicity,
