the proceedings contain 24 papers. the topics discussed include: policies for dynamic clock scheduling;towards higher disk head utilization: extracting free bandwidth from busy disk drives;checking system rules using ...
the proceedings contain 24 papers. the topics discussed include: policies for dynamic clock scheduling;towards higher disk head utilization: extracting free bandwidth from busy disk drives;checking system rules using system-specific, programmer-written compiler extensions;a low-overhead high-performance unified buffer management scheme that exploits sequential and looping references;how to build a trusted database system on untrusted storage;taming the memory hogs: using compiler-inserted releases to manage physical memory intelligently;latency management in storage systems;surplus fair scheduling: a proportional-share CPU scheduling algorithm for symmetric multiprocessors;DEVIL: an IDL for hardware programming;performance-driven processor allocation;end-to-end authorization;system support for bandwidth management and content adaptation in internet applications;operatingsystem management of MEMS-based storage devices;trading capacity for performance in a disk array;exploring failure transparency and the limits of generic recovery;proactive recovery in a byzantine-fault-tolerant system;and design and evaluation of a continuous consistency model for replicated services.
the proceedings contain 24 papers. the topics discussed include: system support for bandwidth management and content adaptation in internet applications;interposed request routing for scalable network storage;processe...
the proceedings contain 24 papers. the topics discussed include: system support for bandwidth management and content adaptation in internet applications;interposed request routing for scalable network storage;processes in KaffeOS: isolation, resource management, and sharing in Java;proactive recovery in a byzantine-fault-tolerant system;surplus fair scheduling: a proportional-share CPU scheduling algorithm for symmetric multiprocessors;and exploring failure transparency and the limits of generic recovery.
Some emerging applications require programs to maintain sensitive state on untrusted hosts. this paper presents the architecture and implementation of a trusted database system, TDB, which leverages a small amount of ...
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Some emerging applications require programs to maintain sensitive state on untrusted hosts. this paper presents the architecture and implementation of a trusted database system, TDB, which leverages a small amount of trusted storage to protect a scalable amount of un-trusted storage. the database is encrypted and validated against a collision-resistant hash kept in trusted storage, so untrusted programs cannot read the database or modify it undetectably. TDB integrates encryption and hashing with a low-level data model, which protects data and metadata uniformly, unlike systems built on top of a conventional database system. the implementation exploits synergies between hashing and log-structured storage. Preliminary performance results show that TDB outperforms an off-the-shelf embedded database system, thus supporting the suitability of the TDB architecture.
MEMS-based storage devices promise significant performance, reliability, and power improvements relative to disk drives. this paper compares and contrasts these two storage technologies and explores how the physical c...
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MEMS-based storage devices promise significant performance, reliability, and power improvements relative to disk drives. this paper compares and contrasts these two storage technologies and explores how the physical characteristics of MEMS-based storage devices change four aspects of operatingsystem (OS) management: request scheduling, data placement, failure management, and power conservation. Straightforward adaptations of existing disk request scheduling algorithms are found to be appropriate for MEMS-based storage devices. A new bipartite data placement scheme is shown to better match these devices' novel mechanical positioning characteristics. With aggressive internal redundancy, MEMS-based storage devices can mask and tolerate failure modes that halt operation or cause data loss for disks. In addition, MEMS-based storage devices simplify power management because the devices can be stopped and started rapidly.
Many boundaries impede the flow of authorization information, forcing applications that span those boundaries into hop-by-hop approaches to authorization. We present a unified approach to authorization. Our approach a...
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Many boundaries impede the flow of authorization information, forcing applications that span those boundaries into hop-by-hop approaches to authorization. We present a unified approach to authorization. Our approach allows applications that span administrative, network, abstraction, and protocol boundaries to understand the end-to-end authority that justifies any given request. the resulting distributed systems are more secure and easier to audit. We describe boundaries that can interfere with end-to-end authorization, and outline our unified approach. We describe the system we built and the applications we adapted to use our unified authorization system, and measure its costs. We conclude that our system is a practical approach to the desirable goal of end-to-end authorization.
this paper describes an asynchronous state-machine replication systemthat tolerates Byzantine faults, which can be caused by malicious attacks or software errors. Our system is the first to recover Byzantine-faulty r...
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this paper describes an asynchronous state-machine replication systemthat tolerates Byzantine faults, which can be caused by malicious attacks or software errors. Our system is the first to recover Byzantine-faulty replicas proactively and it performs well because it uses symmetric rather than public-key cryptography for authentication. the recovery mechanism allows us to tolerate any number of faults over the lifetime of the system provided fewer than 1/3 of the replicas become faulty within a window of vulnerability that is small under normal conditions. the window may increase under a denial-of-service attack but we can detect and respond to such attacks. the paper presents results of experiments showing that overall performance is good and that even a small window of vulnerability has little impact on service latency.
Internet users increasingly rely on publicly avail able data for everything from software installation to investment decisions. Unfortunately, the vast majority of public content on the Internet comes with no integrit...
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Internet users increasingly rely on publicly avail able data for everything from software installation to investment decisions. Unfortunately, the vast majority of public content on the Internet comes with no integrity or authenticity guarantees. this paper presents the self-certifying read-only file system, a content distribution system providing secure, scal able access to public, read-only data. the read-only file system makes the security of published content independent from that of the distribution infrastructure. In a secure area (per haps off-line), a publisher creates a digitally-signed database out of a file system's contents. the publisher then replicates the database on untrusted content-distribution servers, allowing for high availability. the read-only file system protocol furthermore pushes the cryptographic cost of content verification entirely onto clients, allowing servers to scal to a large number of clients. Measurements of an implementation show that an individual server running on a 550 Mhz Pentium III with FreeBSD can support 1, 012 connections per second and 300 concurrent clients compiling a large software package.
systems software such as OS kernels, embedded systems, and libraries must obey many rules for both correctness and performance. Common examples include "accesses to variable A must be guarded by lock B," &qu...
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systems software such as OS kernels, embedded systems, and libraries must obey many rules for both correctness and performance. Common examples include "accesses to variable A must be guarded by lock B," "system calls must check user pointers for validity before using them," and "message handlers should free their buffers as quickly as possible to allow greater parallelism." Unfortunately, adherence to these rules is largely unchecked. this paper attacks this problem by showing how system implementors can use meta-level compilation (MC) to write simple, system-specific compiler extensions that automatically check their code for rule violations. By melding domain-specific knowledge withthe automatic machinery of compilers, MC brings the benefits of language-level checking and optimizing to the higher, "meta" level of the systems implemented in these languages. this paper demonstrates the effectiveness of the MC approach by applying it to four complex, real systems: Linux, OpenBSD, the Xok exokernel, and the FLASH machine's embedded software. MC extensions found roughly 500 errors in these systems and led to numerous kernel patches. Most extensions were less than a hundred lines of code and written by implementors who had a limited understanding of the systems checked.
this paper describes the implementation and evaluation of an operatingsystem module, the Congestion Manager (CM), which provides integrated network flow management and exports a convenient programming interface that ...
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this paper describes the implementation and evaluation of an operatingsystem module, the Congestion Manager (CM), which provides integrated network flow management and exports a convenient programming interface that allows applications to be notified of, and adapt to, changing network conditions. We describe the API by which applications interface withthe CM, and the architectural considerations that factored into the design. To evaluate the architecture and API, we describe our implementations of TCP;a streaming layered audio/video application;and an interactive audio application using the CM, and show that they achieve adaptive behavior without incurring much end-system overhead. All flows including TCP benefit from the sharing of congestion information, and applications are able to incorporate new functionality such as congestion control and adaptive behavior.
MEMS-based storage devices promise significant performance, reliability, and power improvements relative to disk drives. this paper compares and contrasts these two storage technologies and explores how the physical c...
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