Kanaka Juvva

Carnegie Mellon University, Pittsburgh, PA, United States

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Publications (10)0 Total impact

  • K. Juvva
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    ABSTRACT: Push-pull communications is a real-time middleware service that has been implemented on top of a resource kernel operating system. It is a many-to-many communication model that can support multi-participant real-time applications. It covers both “push” (publisher/subscriber model) and “pull” (data transfer initiated by a receiver) communications. Unlike the publisher/subscriber model, different publishers and subscribers can operate at different data rates and also can choose another (intermediate) node to act as their proxy and deliver data at their desired frequency. We specifically address end-to-end predictability of the push-pull model. The scheduling mechanisms in the OS, the middleware architecture and the underlying network QoS support can impact the timeliness of data. We obtain our end-to-end timeliness and bandwidth guarantees by using a resource kernel offering CPU reservations and the use of a guaranteed bandwidth network (DARWIN) between push-pull end-points. We formally analyze the problem of choosing an optimal proxy location within a network. We discuss our implementation of this system and carry out a detailed performance evaluation on an integrated RT-Mach-Darwin testbed at Carnegie Mellon. Our results open up interesting research directions for the scheduling of computation and communication resources for the applications using the push-pull service. The push-pull framework can easily be incorporated in an RT-CORBA Event Service model
    Object-Oriented Real-Time Distributed Computing, 2000. (ISORC 2000) Proceedings. Third IEEE International Symposium on; 02/2000
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    Kanaka Juvva
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    ABSTRACT: In this paper, we extend the Push Pull Communication Model to provide end to end quality of service (QoS) for clients located in distributed and heterogeneous nodes. Push pull communications is a middleware service that has been implemented on top of a Resource Kernel. It is a many to many communication model, which can easily and quickly disseminate information across heterogeneous nodes with flexible communication patterns. It supports both push (data transfer initiated by a sender) and pull (data transfer initiated by a receiver) communications. Nodes with widely differing processing power and networking bandwidth can coordinate and co-exist by the provision of appropriate and automatic support for transformation on data communication frequencies. In particular, different information sources and sinks can operate at different frequencies and also can choose another (intermediate) node to act as their proxy and deliver data at the desired frequency. In this paper, we specifically address the timeliness and bandwidth guarantees of the push pull model. The location of a proxy, the network topology and the underlying network support can impact the timeliness of data. We formally analyze the problem of choosing an optimal proxy location within a network. We obtain the somewhat counter intuitive result that if slightly longer end to end latencies can be tolerated and unicast protocols are used, locating the proxy at the publisher node is the best. The situation turns complex if multicast protocols are used. We show that this problem of optimal proxy allocation can be formulated as a mixed integer programming problem that can be solved efficiently. As an example, we solve the proxy location problem for a high speed vBNS network configuration. We obtain our end to end timeliness and bandwidth guarantees by using a resource kernel offering CPU guarantees at the end points and the use of a guaranteed bandwidth network between push pull clients.
    07/1999;
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    Kanaka Juvva, Raj Rajkumar
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    ABSTRACT: : Current and emerging real-time and multimedia applications like multi-party collaboration, internet telephony and distributed command control systems require the exchange of information over distributed and heterogeneous nodes. Multiple data types including voice, video, sensor data, real-time intelligence data and text are being transported widely across today's information, control and surveillance networks. All such applications can benefit enormously from middleware, operating system and networking services that can support QoS guarantees, high availability, dynamic reconfigurability and scalability. In this paper, we propose a middleware layer called a "Real-Time Push-Pull Communications Service" to easily and quickly disseminate real-time information across heterogeneous nodes. Push-Pull Communications is an extension of the real-time publisher/subscriber model [4], and represents both "push" (data transfer initiated by a sender) and "pull" (data transfer initiated by a receiv...
    04/1999;
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    Kanaka Juvva, Raj Rajkumar
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    ABSTRACT: Real-time and multimedia applications like multi-party collaboration, internet telephony and distributed command control systems require the exchange of information over distributed and heterogeneous nodes. Multiple data types including voice, video, sensor data, real-time intelligence data and text are being transported widely across today's information, control and surveillance networks. All such applications can benefit enormously from middleware, operating system and networking services that can support QoS guarantees, high availability, dynamic reconfigurability and scalability. In this paper, we propose a middleware layer called the "Real-Time Push-Pull Communications Service" to easily and quickly disseminate information across heterogeneous nodes with flexible communication patterns. Realtime push-pull communications is an extension of the real-time publisher/subscriber model, and represents both "push" (data transfer initiated by a sender) and "pull" (data transfer initiated b...
    04/1999;
  • A. Molano, K. Juvva, R. Rajkumar
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    ABSTRACT: Traditional real-time systems have largely avoided the use of disks due to their relative slow speeds and their unpredictability. However, many real-time applications including multimedia systems and real-time database applications benefit significantly from the use of disks to store and access real-time data. We investigate the problem of obtaining guaranteed timely access to files on a disk in a real-time system. Our study focuses on several aspects of this problem of providing a real-time filesystem. First, we consider the use of two real-time disk scheduling algorithms: earliest deadline scheduling and just-in-time scheduling, a variation of aperiodic servers for the disk. The latter algorithm is designed to improve disk throughput that can be hurt when a real-time scheduling algorithm such as EDF is applied directly. Admission control policies with practically acceptable properties of performance and usability are provided. Next, we design and implement a real-time filesystem on the RT-Mach microkernel-based system running a real-time shell. The new interface we develop is based on RT-Mach's resource reservation paradigm and provides guaranteed and timely access for multiple concurrent applications requiring disk bandwidth with different timing and volume requirements. Finally, we perform a detailed performance evaluation of the real-time filesystem including its raw performance. We show the following positive but rather surprising result: our real-time scheduling filesystem not only provides guaranteed and timely access but also does so at relatively high levels of throughput. Traditional disk scheduling algorithms offer completely unacceptable file access latencies for real-time applications and do so only at slightly higher throughput
    Real-Time Systems Symposium, 1997. Proceedings., The 18th IEEE; 01/1998
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    ABSTRACT: The authors focus on two practical considerations that arise in the design of a real-time file system. Firstly, disk bandwidth management should be dynamic, which in turn would allow a QoS manager to dynamically reallocate disk bandwidth to running applications based on their changing needs. Secondly, real-time access to file system data structures should be deterministic, in order to avoid unexpected latencies when accessing files from disk. These issues have implications to the design of the file system and to its schedulability analysis. They address both these problems and present an implementation in RTFS (Real-Time Filesystem Server), a real-time file system supporting disk bandwidth reservation running on top of the Real-Time Mach microkernel. Finally, quantitative comparisons of actual achieved file system bandwidth and response times are used to validate the approach
    10th Euromicro Conference on Real-Time Systems (ECRTS 1998), 17-19 June 1998, berlin, Germany, Proceedings; 01/1998
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    ABSTRACT: We consider the problem of OS resource management for real-time and multimedia systems where multiple activities with different timing constraints must be scheduled concur-rently. Time on a particular resource is shared among its users and must be globally managed in real-time and mul-timedia systems. A resource kernel is meant for use in such systems and is defined to be one which provides timely, guaranteed and protected access to system resources. The resource kernel allows applications to specify only their resource demands leaving the kernel to satisfy those demands using hidden resource management schemes. This separation of resource specification from resource manage-ment allows OS-subsystem-specific customization by extend-ing, optimizing or even replacing resource management schemes. As a result, this resource-centric approach can be implemented with any of several different resource manage-ment schemes. We identify the specific goals of a resource kernel: applica-tions must be able to explicitly state their timeliness require-ments; the kernel must enforce maximum resource usage by applications; the kernel must support high utilization of sys-tem resources; and an application must be able to access different system resources simultaneously. Since the same application consumes a different amount of time on different platforms, the resource kernel must allow such resource consumption times to be portable across platforms, and to be automatically calibrated. Our resource management scheme is based on resource reservation [25] and satisfies these goals. The scheme is not only simple but captures a wide range of solutions developed by the real-time systems community over several years.
    Proc SPIE 12/1997;
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    ABSTRACT: Traditional real-time systems have largely avoided the use of disks due to their relative slow speeds and their unpredictability. However, many real-time applications including multimedia systems and real-time database applications benefit significantly from the use of disks to store and access real-time data. In this paper, we investigate the problem of obtaining guaranteed timely access to files on a disk in a real-time system. Our study focuses on several aspects of this problem of providing a real-time filesystem. First, we consider the use of two real-time disk scheduling algorithms: earliest deadline scheduling and just-in-time scheduling, a variation of aperiodic servers for the disk. The latter algorithm is designed to improve disk throughput that can be hurt when a real-time scheduling algorithm such as EDF is applied directly. Admission control policies with practically acceptable properties of performance and usability are provided. Next, we design and implement a real-time filesystem on the RT-Mach microkernel-based system running a real-time shell. The new interface we develop is based on RT-Mach's resource reservation paradigm and provides guaranteed and timely access for multiple concurrent applications requiring disk bandwidth with different timing and volume requirements. Finally, we perform a detailed performance evaluation of the real-time filesystem including its raw performance. We show the following positive but rather surprising result: our realtime scheduling filesystem not only provides guaranteed and timely access but also does so at relatively high levels of throughput. Traditional disk scheduling algorithms offer completely unacceptable file access latencies for real-time applications and do so only at slightly higher throughput.
    11/1997;
  • A. Molano, K. Juvva, R. Rajkumar