The Experts below are selected from a list of 53508 Experts worldwide ranked by ideXlab platform
Andrew S Tanenbaum - One of the best experts on this subject based on the ideXlab platform.
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reorganizing unix for reliability
Lecture Notes in Computer Science, 2006Co-Authors: Jorrit N. Herder, Ben Gras, Philip Homburg, Andrew S TanenbaumAbstract:In this paper, we discuss the architecture of a modular UNIX-compatible operating system, MINIX3, that provides reliability beyond that of most other systems. With nearly the entire operating system running as a set of User-Mode servers and drivers atop a minimal kernel, the system is fully compartmentalized. By moving most of the code to unprivileged User-Mode processes and restricting the powers of each one, we gain proper fault isolation and limit the damage bugs can do. Moreover, the system has been designed to survive and automatically recover from failures in critical modules, such as device drivers, transparent to applications and without User intervention. We used this new design to develop a highly reliable, open-source, POSIX-conformant member of the UNIX family. The resulting system is freely available and has been downloaded over 75,000 times since its release.
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Asia-Pacific Computer Systems Architecture Conference - Reorganizing UNIX for reliability
Lecture Notes in Computer Science, 2006Co-Authors: Jorrit N. Herder, Ben Gras, Philip Homburg, Herbert Bos, Andrew S TanenbaumAbstract:In this paper, we discuss the architecture of a modular UNIX-compatible operating system, MINIX3, that provides reliability beyond that of most other systems. With nearly the entire operating system running as a set of User-Mode servers and drivers atop a minimal kernel, the system is fully compartmentalized. By moving most of the code to unprivileged User-Mode processes and restricting the powers of each one, we gain proper fault isolation and limit the damage bugs can do. Moreover, the system has been designed to survive and automatically recover from failures in critical modules, such as device drivers, transparent to applications and without User intervention. We used this new design to develop a highly reliable, open-source, POSIX-conformant member of the UNIX family. The resulting system is freely available and has been downloaded over 75,000 times since its release.
Jorrit N. Herder - One of the best experts on this subject based on the ideXlab platform.
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reorganizing unix for reliability
Lecture Notes in Computer Science, 2006Co-Authors: Jorrit N. Herder, Ben Gras, Philip Homburg, Andrew S TanenbaumAbstract:In this paper, we discuss the architecture of a modular UNIX-compatible operating system, MINIX3, that provides reliability beyond that of most other systems. With nearly the entire operating system running as a set of User-Mode servers and drivers atop a minimal kernel, the system is fully compartmentalized. By moving most of the code to unprivileged User-Mode processes and restricting the powers of each one, we gain proper fault isolation and limit the damage bugs can do. Moreover, the system has been designed to survive and automatically recover from failures in critical modules, such as device drivers, transparent to applications and without User intervention. We used this new design to develop a highly reliable, open-source, POSIX-conformant member of the UNIX family. The resulting system is freely available and has been downloaded over 75,000 times since its release.
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Asia-Pacific Computer Systems Architecture Conference - Reorganizing UNIX for reliability
Lecture Notes in Computer Science, 2006Co-Authors: Jorrit N. Herder, Ben Gras, Philip Homburg, Herbert Bos, Andrew S TanenbaumAbstract:In this paper, we discuss the architecture of a modular UNIX-compatible operating system, MINIX3, that provides reliability beyond that of most other systems. With nearly the entire operating system running as a set of User-Mode servers and drivers atop a minimal kernel, the system is fully compartmentalized. By moving most of the code to unprivileged User-Mode processes and restricting the powers of each one, we gain proper fault isolation and limit the damage bugs can do. Moreover, the system has been designed to survive and automatically recover from failures in critical modules, such as device drivers, transparent to applications and without User intervention. We used this new design to develop a highly reliable, open-source, POSIX-conformant member of the UNIX family. The resulting system is freely available and has been downloaded over 75,000 times since its release.
John Michael Tracey - One of the best experts on this subject based on the ideXlab platform.
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high performance memory based web servers kernel and User space performance
USENIX Annual Technical Conference, 2001Co-Authors: Philippe Joubert, Robert B King, Richard Neves, Mark Russinovich, John Michael TraceyAbstract:Web server performance has steadily improved since the inception of the World Wide Web. We observe performance gains of two orders of magnitude between the original process-based Web servers and today’s threaded Web servers. Commercial and academic Web servers achieved much of these gains using new or improved event-notification mechanisms and techniques to eliminate reading and copying data, both of which required new operating system primitives. More recently, experimental and production Web servers began integrating HTTP processing in the TCP/IP stack and providing zero copy access to a kernel-managed cache. These kernelMode Web servers improved upon newer User-Mode Web servers by a factor of two to six. This paper analyzes the significant performance gap between the newer User-Mode and kernel-Mode Web servers on Linux and Windows 2000. Several User-Mode and kernel-Mode Web servers are compared in three areas: data movement, event notification, and communication code path. To establish a User-Mode baseline, the paper measures the performance of highly optimized Web servers. The paper positions these User-Mode implementations with those from related research projects. In particular, the “Adaptive Fast Path Architecture” (AFPA) is described and then used to implement kernel-Mode Web servers on Linux and Windows 2000. AFPA is a platform for implementing kernel-Mode network servers on production operating systems without kernel modifications. AFPA runs on Linux, Windows 2000, AIX, and S/390. The results show that kernel-Mode performance greatly Philippe Joubert and Rich Neves’ current affiliation is ReefEdge Inc. email: philippe,rich@reefedge.com email: rbking2@us.ibm.com Mark Russinovich’s current affiliation is Winternals Software, 3101 Bee Caves Rd, Austin TX 78746. email: mark@sysinternals.com xemail: traceyj@us.ibm.com exceeds the performance of User-Mode servers implementing a variety of performance optimizations. The paper concludes that significant opportunities remain to bridge the gap between User-Mode and kernel-Mode Web server performance.
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USENIX Annual Technical Conference, General Track - High-Performance Memory-Based Web Servers: Kernel and User-Space Performance
2001Co-Authors: Philippe Joubert, Robert B King, Richard Neves, Mark Russinovich, John Michael TraceyAbstract:Web server performance has steadily improved since the inception of the World Wide Web. We observe performance gains of two orders of magnitude between the original process-based Web servers and today’s threaded Web servers. Commercial and academic Web servers achieved much of these gains using new or improved event-notification mechanisms and techniques to eliminate reading and copying data, both of which required new operating system primitives. More recently, experimental and production Web servers began integrating HTTP processing in the TCP/IP stack and providing zero copy access to a kernel-managed cache. These kernelMode Web servers improved upon newer User-Mode Web servers by a factor of two to six. This paper analyzes the significant performance gap between the newer User-Mode and kernel-Mode Web servers on Linux and Windows 2000. Several User-Mode and kernel-Mode Web servers are compared in three areas: data movement, event notification, and communication code path. To establish a User-Mode baseline, the paper measures the performance of highly optimized Web servers. The paper positions these User-Mode implementations with those from related research projects. In particular, the “Adaptive Fast Path Architecture” (AFPA) is described and then used to implement kernel-Mode Web servers on Linux and Windows 2000. AFPA is a platform for implementing kernel-Mode network servers on production operating systems without kernel modifications. AFPA runs on Linux, Windows 2000, AIX, and S/390. The results show that kernel-Mode performance greatly Philippe Joubert and Rich Neves’ current affiliation is ReefEdge Inc. email: philippe,rich@reefedge.com email: rbking2@us.ibm.com Mark Russinovich’s current affiliation is Winternals Software, 3101 Bee Caves Rd, Austin TX 78746. email: mark@sysinternals.com xemail: traceyj@us.ibm.com exceeds the performance of User-Mode servers implementing a variety of performance optimizations. The paper concludes that significant opportunities remain to bridge the gap between User-Mode and kernel-Mode Web server performance.
Dhabaleswar K Panda - One of the best experts on this subject based on the ideXlab platform.
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high performance mpi datatype support with User Mode memory registration challenges designs and benefits
International Conference on Cluster Computing, 2015Co-Authors: Hari Subramoni, Khaled Hamidouche, Dhabaleswar K PandaAbstract:Noncontiguous data communication has been heavily adopted in scientific applications, especially for those written with MPI. Common strategies to handle noncontiguous data, like packing/unpacking, incur significant performance overhead during communication, which could become as a barrier of using MPI derived datatypes. Recently, a novel feature of Mellanox InfiniBand, called User-Mode Memory Registration (UMR), has been introduced for noncontiguous data communication. UMR has the potential to support MPI derived datatype communication efficiently without the overhead of packing/unpacking. In this paper, we analyze the UMR feature and study its basic performance with InfiniBand verbs-level micro-benchmarks. With this knowledge, we propose UMR-based schemes to support zero-copy datatype communication at MPI level. We show that a naive integration of UMR with an MPI stack could not bring performance benefits over existing schemes. Thus we propose two schemes -- UMR Pool and UMR Cache -- to enable high performance MPI datatype communication with UMR. To the best of our knowledge, this is the first paper to study, analyze, and design MPI noncontiguous data communication using the UMR feature. We propose and implement UMR-based designs on top of MVAPICH2 library. The experimental results at the microbenchmark level show that the proposed UMR-based design is able to deliver 4X performance improvement in latency for large message vector benchmarks over the packing/unpacking scheme. At the application level, for a 3D stencil communication kernel with MPI derived datatype on 512 processes, the optimized UMR-based design outperforms the packing/unpacking scheme by 27% in execution time.
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CLUSTER - High Performance MPI Datatype Support with User-Mode Memory Registration: Challenges, Designs, and Benefits
2015 IEEE International Conference on Cluster Computing, 2015Co-Authors: Hari Subramoni, Khaled Hamidouche, Dhabaleswar K PandaAbstract:Noncontiguous data communication has been heavily adopted in scientific applications, especially for those written with MPI. Common strategies to handle noncontiguous data, like packing/unpacking, incur significant performance overhead during communication, which could become as a barrier of using MPI derived datatypes. Recently, a novel feature of Mellanox InfiniBand, called User-Mode Memory Registration (UMR), has been introduced for noncontiguous data communication. UMR has the potential to support MPI derived datatype communication efficiently without the overhead of packing/unpacking. In this paper, we analyze the UMR feature and study its basic performance with InfiniBand verbs-level micro-benchmarks. With this knowledge, we propose UMR-based schemes to support zero-copy datatype communication at MPI level. We show that a naive integration of UMR with an MPI stack could not bring performance benefits over existing schemes. Thus we propose two schemes -- UMR Pool and UMR Cache -- to enable high performance MPI datatype communication with UMR. To the best of our knowledge, this is the first paper to study, analyze, and design MPI noncontiguous data communication using the UMR feature. We propose and implement UMR-based designs on top of MVAPICH2 library. The experimental results at the microbenchmark level show that the proposed UMR-based design is able to deliver 4X performance improvement in latency for large message vector benchmarks over the packing/unpacking scheme. At the application level, for a 3D stencil communication kernel with MPI derived datatype on 512 processes, the optimized UMR-based design outperforms the packing/unpacking scheme by 27% in execution time.
Wang Lei - One of the best experts on this subject based on the ideXlab platform.
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smartphone multi User Mode permission management method and smartphone multi User Mode permission management system
2013Co-Authors: Yuan Cangzhou, Guo Fei, Wang LeiAbstract:The invention discloses a smartphone multi-User Mode permission management method. According to the smartphone multi-User Mode permission management method, firstly, User permissions are set in four levels, and operation permissions of Users in each level are set; then unlocking codes, smartphone application and resource access permissions are set for the Users in all the levels; and therefore set accessible smartphone applications and set accessible smartphone resources of the Users in all the levels are displayed. The smartphone multi-User Mode permission management method can also be used for providing three switching methods for switching among the Users in all the levels according to a current using state of a smartphone, and when a User in a low permission level is converted to a User in a high permission level, permission validation is needed. The invention further discloses a smartphone multi-User Mode permission management system, and the smartphone multi-User Mode permission management can be realized through a modular design. The smartphone multi-User Mode permission management method and the smartphone multi-User Mode permission management system have the advantage that due to the fact that the using permissions of the different Users are set, the purpose of protecting sensitive information in the smartphone is achieved, and swift switching of the User permissions can also be achieved.
