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169
Labels and event processes in the asbestos operating system
- In Proc. 20th ACM Symp. on Operating System Principles (SOSP
, 2005
"... Asbestos, a new prototype operating system, provides novel labeling and isolation mechanisms that help contain the effects of exploitable software flaws. Applications can express a wide range of policies with Asbestos’s kernel-enforced label mechanism, including controls on inter-process communicati ..."
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Cited by 181 (15 self)
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Asbestos, a new prototype operating system, provides novel labeling and isolation mechanisms that help contain the effects of exploitable software flaws. Applications can express a wide range of policies with Asbestos’s kernel-enforced label mechanism, including controls on inter-process communication and systemwide information flow. A new event process abstraction provides lightweight, isolated contexts within a single process, allowing the same process to act on behalf of multiple users while preventing it from leaking any single user’s data to any other user. A Web server that uses Asbestos labels to isolate user data requires about 1.5 memory pages per user, demonstrating that additional security can come at an acceptable cost.
Diagnosing performance overheads in the Xen virtual machine environment
- In VEE ’05: Proc. 1st ACM/USENIX International Conference on Virtual Execution Environments
, 2005
"... Xen) are experiencing a resurgence of interest for diverse uses including server consolidation and shared hosting. An application’s performance in a virtual machine environment can differ markedly from its performance in a nonvirtualized environment because of interactions with the underlying virtua ..."
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Cited by 141 (9 self)
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Xen) are experiencing a resurgence of interest for diverse uses including server consolidation and shared hosting. An application’s performance in a virtual machine environment can differ markedly from its performance in a nonvirtualized environment because of interactions with the underlying virtual machine monitor and other virtual machines. However, few tools are currently available to help debug performance problems in virtual machine environments. In this paper, we present Xenoprof, a system-wide statistical profiling toolkit implemented for the Xen virtual machine environment. The toolkit enables coordinated profiling of multiple VMs in a system to obtain the distribution of hardware events such as clock cycles and cache and TLB misses. We use our toolkit to analyze performance overheads incurred by networking applications running in Xen VMs. We focus on networking applications since virtualizing network I/O devices is relatively expensive. Our experimental results quantify Xen’s performance overheads for network I/O device virtualization in uni- and multi-processor systems. Our results identify the main sources of this overhead which should be the focus of Xen optimization efforts. We also show how our profiling toolkit was used to uncover and resolve performance bugs that we encountered in our experiments which caused unexpected application behavior.
Protothreads: simplifying event-driven programming of memory-constrained embedded systems.
- In SenSys ’06: Proceedings of the 4th international conference on Embedded networked sensor systems
, 2006
"... Abstract Event-driven programming is a popular model for writing programs for tiny embedded systems and sensor network nodes. While event-driven programming can keep the memory overhead down, it enforces a state machine programming style which makes many programs difficult to write, maintain, and d ..."
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Cited by 119 (12 self)
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Abstract Event-driven programming is a popular model for writing programs for tiny embedded systems and sensor network nodes. While event-driven programming can keep the memory overhead down, it enforces a state machine programming style which makes many programs difficult to write, maintain, and debug. We present a novel programming abstraction called protothreads that makes it possible to write eventdriven programs in a thread-like style, with a memory overhead of only two bytes per protothread. We show that protothreads significantly reduce the complexity of a number of widely used programs previously written with event-driven state machines. For the examined programs the majority of the state machines could be entirely removed. In the other cases the number of states and transitions was drastically decreased. With protothreads the number of lines of code was reduced by one third. The execution time overhead of protothreads is on the order of a few processor cycles.
Scala actors: Unifying thread-based and event-based programming
- Theor. Comput. Sci
, 2009
"... doi:10.1016/j.tcs.2008.09.019 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is ..."
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Cited by 103 (9 self)
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doi:10.1016/j.tcs.2008.09.019 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Manuscript
The Architecture of PIER: an Internet-Scale Query Processor
- In CIDR
, 2005
"... This paper presents the architecture of PIER , an Internetscale query engine we have been building over the last three years. PIER is the first general-purpose relational query processor targeted at a peer-to-peer (p2p) architecture of thousands or millions of participating nodes on the Internet. ..."
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Cited by 88 (8 self)
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This paper presents the architecture of PIER , an Internetscale query engine we have been building over the last three years. PIER is the first general-purpose relational query processor targeted at a peer-to-peer (p2p) architecture of thousands or millions of participating nodes on the Internet. It supports massively distributed, database-style dataflows for snapshot and continuous queries. It is intended to serve as a building block for a diverse set of Internet-scale informationcentric applications, particularly those that tap into the standardized data readily available on networked machines, including packet headers, system logs, and file names
An Overview of the Singularity Project
, 2005
"... Singularity is a research project in Microsoft Research that started with the question: what would a software platform look like if it was designed from scratch with the primary goal of dependability? Singularity is working to answer this question by building on advances in programming languages a ..."
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Cited by 82 (7 self)
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Singularity is a research project in Microsoft Research that started with the question: what would a software platform look like if it was designed from scratch with the primary goal of dependability? Singularity is working to answer this question by building on advances in programming languages and tools to develop a new system architecture and operating system (named Singularity), with the aim of producing a more robust and dependable software platform. Singularity demonstrates the practicality of new technologies and architectural decisions, which should lead to the construction of more robust and dependable systems.
Performance of multithreaded chip multiprocessors and implications for operating system design
- In USENIX 2005 Annual Technical Conference
, 2005
"... An operating system’s design is often influenced by the architecture of the target hardware. While uniprocessor and multiprocessor architectures are well understood, such is not the case for multithreaded chip multiprocessors (CMT) – a new generation of processors designed to improve performance of ..."
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Cited by 73 (0 self)
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An operating system’s design is often influenced by the architecture of the target hardware. While uniprocessor and multiprocessor architectures are well understood, such is not the case for multithreaded chip multiprocessors (CMT) – a new generation of processors designed to improve performance of memory-intensive applications. The first systems equipped with CMT processors are just becoming available, so it is critical that we now understand how to obtain the best performance from such systems. The goal of our work is to understand the fundamentals of CMT performance and identify the implications for operating system design. We have analyzed how the performance of a CMT processor is affected by contention for the processor pipeline, the L1 data cache, and the L2 cache, and have investigated operating system approaches to the management of these performance-critical resources. Having found that contention for the L2 cache can have the greatest negative impact on processor performance, we have quantified the potential performance improvement that can be achieved from L2-aware OS scheduling. We evaluated a scheduling policy based on the balance-set principle and found that it has a potential to reduce miss ratios in the L2 by 19-37 % and improve processor throughput by 27-45%. To achieve a similar improvement in hardware requires doubling the size of the L2 cache. 1.
Flexsc: Flexible System Call Scheduling with Exception-Less System Calls
- In 9th USENIX Symposium on Operating Systems Design and Implementation (OSDI) (2010
"... For the past 30+ years, system calls have been the de facto interface used by applications to request services from the operating system kernel. System calls have almost universally been implemented as a synchronous mechanism, where a special processor instruction is used to yield userspace executio ..."
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Cited by 56 (2 self)
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For the past 30+ years, system calls have been the de facto interface used by applications to request services from the operating system kernel. System calls have almost universally been implemented as a synchronous mechanism, where a special processor instruction is used to yield userspace execution to the kernel. In the first part of this paper, we evaluate the performance impact of traditional synchronous system calls on system intensive workloads. We show that synchronous system calls negatively affect performance in a significant way, primarily because of pipeline flushing and pollution of key processor structures (e.g., TLB, data and instruction caches, etc.). We propose a new mechanism for applications to request services from the operating system kernel: exception-less system calls. They improve processor efficiency by enabling flexibility in the scheduling of operating system work, which in turn can lead to significantly increased temporal and spacial locality of execution in both user and kernel space, thus reducing pollution effects on processor structures. Exception-less system calls are particularly effective on multicore processors. They primarily target highly threaded server applications, such as Web servers and database servers. We present FlexSC, an implementation of exceptionless system calls in the Linux kernel, and an accompanying user-mode thread package (FlexSC-Threads), binary compatible with POSIX threads, that translates legacy synchronous system calls into exception-less ones transparently to applications. We show how FlexSC improves performance of Apache by up to 116%, MySQL by up to 40%, and BIND by up to 105 % while requiring no modifications to the applications. 1
The Declarative Imperative Experiences and Conjectures in Distributed Logic
"... The rise of multicore processors and cloud computing is putting enormous pressure on the software community to find solutions to the difficulty of parallel and distributed programming. At the same time, there is more—and more varied—interest in data-centric programming languages than at any time in ..."
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Cited by 50 (5 self)
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The rise of multicore processors and cloud computing is putting enormous pressure on the software community to find solutions to the difficulty of parallel and distributed programming. At the same time, there is more—and more varied—interest in data-centric programming languages than at any time in computing history, in part because these languages parallelize naturally. This juxtaposition raises the possibility that the theory of declarative database query languages can provide a foundation for the next generation of parallel and distributed programming languages. In this paper I reflect on my group’s experience over seven years using Datalog extensions to build networking protocols and distributed systems. Based on that experience, I present a number of theoretical conjectures that may both interest the database community, and clarify important practical issues in distributed computing. Most importantly, I make a case for database researchers to take a leadership role in addressing the impending programming crisis. This is an extended version of an invited lecture at the ACM PODS 2010 conference [32]. 1.
Combining events and threads for scalable network services
- In Proc. 2007 PLDI
, 2007
"... This paper proposes to combine two seemingly opposed programming models for building massively concurrent network services: the event-driven model and the multithreaded model. The result is a hybrid design that offers the best of both worlds—the ease of use and expressiveness of threads and the flex ..."
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Cited by 44 (2 self)
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This paper proposes to combine two seemingly opposed programming models for building massively concurrent network services: the event-driven model and the multithreaded model. The result is a hybrid design that offers the best of both worlds—the ease of use and expressiveness of threads and the flexibility and performance of events. This paper shows how the hybrid model can be implemented entirely at the application level using concurrency monads in Haskell, which provides type-safe abstractions for both events and threads. This approach simplifies the development of massively concurrent software in a way that scales to real-world network services. The Haskell implementation supports exceptions, symmetrical multiprocessing, software transactional memory, asynchronous I/O mechanisms and application-level network protocol stacks. Experimental results demonstrate that this monad-based approach has good performance: the threads are extremely lightweight (scaling to ten million threads), and the I/O performance compares favorably to that of Linux NPTL. Categories and Subject Descriptors D.1.1 [Programming techniques]:
