waashk/dblp huggingface dataset:
isolation with flexibility: a resource management framework for central servers. proportional-share resource management is becoming increasingly important in today's computing environments. in particular, the growing use of the computational resources of central service providers argues for a proportional-share approach that allows resource principals to obtain allocations that reflect their relative importance. in such environments, resource principals must be isolated from one another to prevent the activities of one principal from impinging on the resource rights of others. however, such isolation limits the flexibility with which resource allocations can be modified to reflect the actual needs of applications. we present extensions to the lottery-scheduling resource management framework that increase its flexibility while preserving its ability to provide secure isolation. to demonstrate how this extended framework safely overcomes the limits imposed by existing proportional-share schemes, we have implemented a prototype system that uses the framework to manage cpu time, physical memory, and disk bandwidth. we present the results of experiments that evaluate the prototype, and we show that our framework has the potential to enable server applications to achieve significant gains in performance.
scalability in the xfs file system. in this paper we describe the architecture and design of a new file system, xfs, for silicon graphics' irix operating system. it is a general purpose file system for use on both workstations and servers. the focus of the paper is on the mechanisms used by xfs to scale capacity and performance in supporting very large file systems. the large file system support includes mechanisms for managing large files, large numbers of files, large directories, and very high performance i/o. in discussing the mechanisms used for scalability we include both descriptions of the xfs on-disk data structures and analyses of why they were chosen. we discuss in detail our use of b+ trees in place of many of the more traditional linear file system structures. xfs has been shipping to customers since december of 1994 in a version of irix 5.3, and we are continuing to improve its performance and add features in upcoming releases. we include performance results from running on the latest version of xfs to demonstrate the viability of our design.
turning the aix operating system into an mp-capable os. this paper describes those mp features that bull and ibm together introduced into the aix operating system to support the symmetric multiprocessor machine marketed by bull under the escala name and by ibm under the rs/6000 models g30, j30 and r30 names. the powerpc architecture and the aix operating system present some specific challenges. we present the major problems encountered and how they were solved.
time-based fairness improves performance in multi-rate wlans. the performance seen by individual clients on a wireless local area network (wlan) is heavily influenced by the manner in which wireless channel capacity is allocated. the popular mac protocol dcf (distributed coordination function) used in 802.11 networks provides equal long-term transmission opportunities to competing nodes when all nodes experience similar channel conditions. when similar-sized packets are also used, dcf leads to equal achieved throughputs (throughput-based fairness) among contending nodes. because of varying indoor channel conditions, the 802.11 standard supports multiple data transmission rates to exploit the trade-off between data rate and bit error rate. this leads to considerable rate diversity, particularly when the network is congested. under such conditions, throughput-based fairness can lead to drastically reduced aggregate throughput. in this paper, we argue the advantages of time-based fairness, in which each competing node receives an equal share of the wireless channel occupancy time. we demonstrate that this notion of fairness can lead to significant improvements in aggregate performance while still guaranteeing that no node receives worse channel access than it would in a single-rate wlan. we also describe our algorithm, tbr (time-based regulator), which runs on the ap and works with any mac protocol to provide time-based fairness by regulating packets. through experiments, we show that our practical and backward compatible implementation of tbr in conjunction with an existing implementation of dcf achieves time-based fairness.
role classification of hosts within enterprise networks based on connection patterns. role classification involves grouping hosts into related roles. it exposes the logical structure of a network, simplifies network management tasks such as policy checking and network segmentation, and can be used to improve the accuracy of network monitoring and analysis algorithms such as intrusion detection. this paper defines the role classification problem and introduces two practical algorithms that group hosts based on observed connection patterns while dealing with changes in these patterns over time. the algorithms have been implemented in a commercial network monitoring and analysis product for enterprise networks. results from grouping two enterprise networks show that the number of groups identified by our algorithms can be two orders of magnitude smaller than the number of hosts and that the way our algorithms group hosts highly reflect the logical structure of the networks.
simple continuous media storage server on real-time mach. this paper presents the design and implementation of a simple continuous media storage server: cras on real-time mach. cras is a specially optimized storage system for retrieving multiple continuous media streams such as audio and video from a disk at constant rates for small scale distributed multimedia systems. many previous continuous media storage servers have focussed on high throughput for supporting as many video sessions as possible. however, these servers are too big and complicated for playback applications that retrieve continuous media data from the local disks of personal computers. also, there are many continuous media systems requiring small continuous media storage servers that can be shared by a small number of applications. to reduce hardware costs, the servers should run on less powerful computers. this means that the previous big and complicated servers are not appropriate for such small scale environments. we show that our simple continuous media server for small scale systems can guarantee the retrieval of continuous media data at a constant rate, and provide high throughput even though it is compact and simple.
x through the firewall, and other application relay. organizations often impose an administrative security policy when they connect to other organizations on a public network such as the internet. many applications have their own notions of security, or they simply rely on the security of the underlying protocols. using the x window system as a case study, we describe some techniques for building application-specific relays that allow the use of applications across organizational boundaries. in particular, we focus on analyzing administrative and application-specific security policies to construct solutions that satisfy the security requirements while providing the necessary functions of the applications.
email prioritization: reducing delays on legitimate mail caused by junk mail. in recent years the volume of junk email (spam, virus etc.) has increased dramatically. these unwanted messages clutter up users' mailboxes, consume server resources, and cause delays to the delivery of mail. this paper presents an approach that ensures that nonjunk mail is delivered without excessive delay, at the expense of delaying junk mail. using data from two internet-facing mail servers, we show how it is possible to simply and accurately predict whether the next message sent from a particular server will be good or junk, by monitoring the types of messages previously sent. the prediction can be used to delay acceptance of junk mail, and prioritize good mail through the mail server, ensuring that loading is reduced and delays are low, even if the server is overloaded. the paper includes a review of server-based anti-spam techniques, and an evaluation of these against the data. we develop and calibrate a model of mail server performance, and use it to predict the performance of the prioritization scheme. we also describe an implementation on a standard mail server.
phonestation, moving the telephone onto the virtual desktop. phonestation is a system that provides a sun microsystems sparcstation with complete control over an ordinary telephone line. it consists of a telephone line interface unit with loop control and touch tone detection, a suite of supporting software libraries that include digital signal processing for call progress monitoring, text-to-speech conversion, telephone line control, and phonescript, a high level procedural language that uses tcl for building interactive based application.
metadata logging in an nfs server. over the last few years, there have been several efforts to use logging to improve performance, reliability, and recovery times of file systems. the two major techniques are metadata logging, where the log records metadata changes and is a supplement to the on-disk file system, and log-structured file systems, whose log is their only on-disk representation. when the file system is mainly or wholly accessed through the network file system (nfs) protocol, it adds new considerations to the suitability of the logging technique. nfs requires that all operations be updated to stable storage before returning. as a result, file system implementations that were effective for local access may perform poorly on an nfs server. this paper analyzes the issues regarding the use of logging on an nfs server, and describes an implementation of a bsd fast file system (ffs) with metadata logging that performs effectively for a dedicated nfs server.
web++: a system for fast and reliable web service. we describe the design of a system for a fast and reliable http service termed web++. web++ achieves high reliability by dynamically replicating web data among multiple web servers. web++ selects a server which is available and that is expected to provide the fastest response time. furthermore, web++ guarantees data delivery, provided that at least one server containing the requested data is available. after detecting a server failure, web++ client requests are satisfied transparently to the client by another server. web++ is built on top of the standard http protocol and does not require any changes either in existing web browsers, or the installation of any software on the client side. we implement a web++ prototype; performance experiments indicate that web++ improves the client response time on average by 36.6%, and in many cases by as much as 59%, when compared with the current web performance.
implementing real time packet forwarding policies using streams. this paper describes an implementation of the class based queueing (cbq) mechanisms proposed by sally floyd and van jacobson to provide real time policies for packet forwarding. cbq allows the traffic flows sharing a data link to be guaranteed a share of the bandwidth when the link is congested, yet allows flexible sharing of the unused bandwidth when the link is unloaded. in addition, cbq provides mechanisms which give flows requiring low delay priority over other flows. in this way, links can be shared by multiple flows yet still meet the policy and quality of service (qos) requirements of the flows. we present a brief description of the implementation and some preliminary preformance measurements. the problems of packet classification are addressed in a flexible and extensible, yet efficient manner, and whilst the streams implementation cannot cope with very high speed interfaces, it can cope with the serial link speeds that are likely to be loaded.
events in an rpc based distributed system. we show how to build a distributed system allowing objects to register interest in and receive notifications of events in other objects. the system is built on top of a pair of interfaces that are interesting only in their extreme simplicity. we then present a simple and efficient implementation of these interfaces. we then show how more complex functionality can be introduced to the system by adding third-party services. these services can be added without changing the simple interfaces, and without changing the objects in the system that do not need the functionality of those services. finally, we note a number of open issues that remain, and attempt to draw some conclusions based on the work.
reliability and security in the codeen content distribution network. with the advent of large-scale, wide-area networking testbeds, researchers can deploy long-running distributed services that interact with other resources on the web. the codeen content distribution network, deployed on planetlab, uses a network of caching web proxy servers to intelligently distribute and cache requests from a potentially large client population. we have been running this system nearly continuously since june 2003, allowing open access from any client in the world. in that time, it has become the most heavily-used long-running service on planetlab, handling over four million accesses per day. in this paper, we discuss the design of our system, focusing on the reliability and security mechanisms that have kept the service in operation. our reliability mechanisms assess node health, preventing failing nodes from disrupting the operation of the overall system. our security mechanisms protect nodes from being exploited and from being implicated in malicious activities, problems that commonly plague other open proxies. we believe that future services, especially peer-to-peer systems, will require similar mechanisms as more services are deployed on non-dedicated distributed systems, and as their interaction with existing protocols and systems increases. our experiences with codeen and our data on its availability should serve as an important starting point for designers of future systems.
gnu mailman, internationalized. gnu mailman is a mailing list management system that has been in production use since 1998. in december 2002, a version 2.1 was released containing many new features. this paper will describe one of the most important - mailman 2.1's internationalization support. presented here are the tools that were built and the approaches mailman took to marking and translating text, as well a review of some of the benefits and pitfalls of mailman's solution. also presented will be some future directions for internationalized mailman, as well as other complex python applications such as zope.
the case for compressed caching in virtual memory systems. compressed caching uses part of the available ram to hold pages in compressed form, effectively adding a new level to the virtual memory hierarchy. this level attempts to bridge the huge performance gap between normal (uncompressed) ram and disk. unfortunately, previous studies did not show a consistent benefit from the use of compressed virtual memory. in this study, we show that technology trends favor compressed virtual memory--it is attractive now, offering reduction of paging costs of several tens of percent, and it will be increasingly attractive as cpu speeds increase faster than disk speeds. two of the elements of our approach are innovative. first, we introduce novel compression algorithms suited to compressing in-memory data representations. these algorithms are competitive with more mature ziv-lempel compressors, and complement them. second, we adaptively determine how much memory (if at all) should be compressed by keeping track of recent program behavior. this solves the problem of different programs, or phases within the same program, performing best for different amounts of compressed memory.
laddis: the next generation in nfs file server benchmarking. the ability to compare the performance of various nfs(1) file server configurations from several vendors is critically important to a computing facility when selecting an nfs file server. to date, nhfsstone(2) has been a popular means of characterizing nfs file server performance. however, several deficiencies have been found in nhfsstone. the laddis nfs file server benchmark has been developed to resolve nhfsstone's shortcomings and provide new functionality. the standard performance evaluation corporation (spec(3)) released the system file server (sfs) release 1.0 benchmark suite, which contains 097.laddis, as an industry-standard nfs file server benchmark in april 1993. this paper describes the major technical issues involved in developing the benchmark and the rationale used to establish default 097.laddis workload parameter values. where appropriate, areas for further research are identified and encouraged.
latency analysis of tcp on an atm network. in this paper we characterize the latency of the bsd 4.4 alpha implementation of tcp on an atm network. latency reduction is a difficult task, and careful analysis is the first step towards reduction. we investigate the impact of both the network controller and the protocol implementation on latency. we find that a low latency network controller has a significant impact on the overall latency of tcp. we also characterize the impact on latency of some widely discussed improvements to tcp, such as header prediction and the combination of the checksum calculation with data copying.
operating system support for multi-user, remote, graphical interaction. the emergence of thin client computing and multi-user, remote, graphical interaction revives a range of operating system research issues long dormant, and introduces new directions as well. this paper investigates the effect of operating system design and implementation on the performance of thin client service and interactive applications. we contend that the key performance metric for this type of system and its applications is user-perceived latency and we give a structured approach for investigating operating system design with this criterion in mind. in particular, we apply our approach to a quantitative comparison and analysis of windows nt, terminal server edition (tse), and linux with the x windows system, two popular implementations of thin client service. we find that the processor and memory scheduling algorithms in both operating systems are not tuned for thin client service. under heavy cpu and memory load, we observed user-perceived latencies up to 100 times beyond the threshold of human perception. even in the idle state, these systems induce unnecessary latency. tse performs particularly poorly despite scheduler modifications to improve interactive responsiveness. we also show that tse's network protocol outperforms x by up to six times, and also makes use of a bitmap cache which is essential for handling dynamic elements of modern user interfaces and can reduce network load in these cases by up to 2000%.
snp: an interface for secure network programming. snp provides a high-level abstraction for secure end-to-end network communications. it supports both stream and datagram semantics with security guarantees (e.g., data origin authenticity, data integrity and data confidentiality). it is designed to resemble the berkeley sockets interface so that security can be easily retrofitted into existing socket programs with only minor modifications. snp is built on top of gss-api, thus making it relatively portable across different authentication mechanisms conforming to gss-api. snp hides the details of gss-api (e.g., credentials and contexts management), the communication sublayer as well as the cryptographic sublayer from the application programmers. it also encapsulates security sensitive information, thus preventing accidental or intentional disclosure by an application program.
measuring and characterizing system behavior using kernel-level event logging. analyzing the dynamic behavior and performance of complex software systems is diffcult. currently available systems either analyze each process in isolation, only provide system level cumulative statistics, or provide a fixed and limited number of process group related statistics. the linux trace toolkit (ltt) introduced here provides a novel, modular, and extensible way of recording and analyzing complete system behavior. because all significant system events are recorded, it is possible to analyze any desired subset of the running processes, and for instance distinguish between the time spent waiting for some relevant event (data from disk or another process) versus time spent waiting for some unrelated process to use up its time slice. despite the extensive information gathered, experimental results show that the ltt time and memory overhead is minimal (< 2:5% when observing core kernel events). moreover, due to the ltt and linux kernel modularity and open source code availability, the system is easily extended both in terms of system events gathered, and of later post-processing and graphical presentation.
sift - a tool for wide-area information dissemination. the dissemination model is becoming increasingly important in wide-area information system. in this model, the user subscribes to an information dissemination service by submitting profiles that describe his interests. he then passively receives new, filtered information. the stanford information filtering tool (sift) is a tool to help provide such service. it supports full-text filtering using well-known information retrieval models. the sift filtering engine implements novel indexing techniques, capable of processing large volumes of information against a large number of profiles. it runs on several major unix platforms and is freely available to the public. in this paper we present sift's approach to user interest modeling and user-server communication. we demonstrate the processing capability of sift by describing a running server that disseminates usenet news. we present an empirical study of sift's performance, examining its main memory requirement and ability to scale with information volume and user population.
clue tables: a distributed, dynamic-binding naming mechanism. this paper presents a distributed, dynamic naming mechanism called clue tables for building highly scalable, highly available distributed file systems. the clue tables naming mechanism is distinctive in three aspects. first, it is designed to cope well with the hierarchical structure of the modern large-scale computer networks. second, it implicitlycarries out load balancing among servers to improve systemscalability. third, it supports file replication and dynamically designates a primary copy to resolve possible data inconsistency. this paper also reports a performance evaluation of the clue tables mechanism when compared with nfs, a popular distributed file system.
anonymous rpc: low-latency protection in a 64-bit address space. in this paper, we propose a method of reducing the latency of cross-domain remote procedure call (rpc). traditional systems use separate address spaces to provide memory protection between separate processes, but even with a highly optimized rpc system, the cost of switching between address spaces can make cross-domain rpc prohibitively expensive. our approach is to use anonymity instead of hardware page tables for protection. logically independent memory segments are placed at random locations in the same address space and protection domain. with 64-bit virtual addresses, it is unlikely that a process will be able to locate any other segment by accidental or malicious memory probes; it is impossible to corrupt a segment without knowing its location. the benefit is that a cross-domain rpc need not involve a hardware context switch. measurements of our prototype implementation show that a round-trip null rpc takes only 7.7us on an intel 486-33.