Efficient Scatter Communication in Wormhole k-Ary n-Cubes with Multidestination Message Passing

This paper presents efficient ways to implement one-to-all scatter communication on k-ary n-cubes with multidestination message-passing. Earlier researchers have applied multidestination message-passing to support non-personalized communications. In this paper, for the first time in the literature, we demonstrate that multidestination message-passing can also be used to support efficient personalized communication. Current parallel systems use either a sequential tree-based (ST) scheme or a binomial tree-based (BT) scheme with unicast message-passing to implement scatter. First, we show that the ST scheme achieves the lower bound just for a narrow range of message lengths. Next, we show that the BT scheme has a better overall performance compared to ST but, it can never achieve the lower bound. Finally, we propose a sequential multidestination tree-based (SMT) scheme using multidestination messages which minimizes the scatter latency as well as achieves the lower bound. This scheme a..

Communication Modeling of Heterogeneous Networks of Workstations for Performance Characterization of Collective Operations

Networks of Workstations (NOW) have become an attractive alternative platform for high performance computing. Due to the commodity nature of workstations and interconnects and due to the multiplicity of vendors and platforms, the NOW environments are being gradually redefined as Heterogeneous Networks of Workstations (HNOW). Having an accurate model for the communication in HNOW systems is crucial for design and evaluation of efficient communication layers for such systems. In this paper we present a model for point-to-point communication in HNOW systems and show how it can be used for characterizing the performance of different collective communication operations. In particular, we show how the performance of broadcast, scatter, and gather operations can be modeled and analyzed. We also verify the accuracy of our proposed model by using an experimental HNOW testbed. Furthermore, it is shown how this model can be used for comparing the performance of different collective communication algorithms. We also show how the effect of heterogeneity on the performance of collective communication operations can be predicted

Comparison and Evaluation of Design Choices for Implementing the Virtual Interface Architecture (VIA)

The Virtual Interface Architecture (VIA) specification has been developed to standardize user-level network interfaces that provide low latency, high bandwidth communications. Few hardware and software implementations of VIA exist. Since the VIA specification is flexible, different choices exist for implementing various components of VIA such as doorbells, address translation methods, and completion queues. Although previous studies have evaluated the overall performance of different VIA implementations, there has not been a comparative study on the performance of VIA components. In this paper, we evaluate and compare the performance of different implementations of essential VIA components. We discuss the pros and cons of each design approach and describe the required support for implementing each of them. As a user application, we use the NAS Parallel Benchmarks to study the effect of caching the address translation tables on the NIC and to study design issues involved in implementing completion queues. As a hardware platform we use the IBM Net nity SP cluster running the NT 4.0 operating system and a Myrinet connected cluster of PCs running the Linux operating system

Efficient collective communication on heterogeneous networks of workstations

banikaze,moorthy,panda

Efficient Collective Communication on Heterogeneous Networks of Workstations

Networks of Workstations (NOW) have become an attractive alternative platform for high performance computing. Due to the commodity nature of workstations and interconnects and due to the multiplicity of vendors and platforms, the NOW environments are being gradually redefined as Heterogeneous Networks of Workstations (HNOW) environments. This paper presents a new framework for implementing collective communication operations (as defined by the Message Passing Interface (MPI) standard) efficiently for the emerging HNOW environments. We first classify different types of heterogeneity in HNOW and then focus on one important characteristic: communication capabilities of workstations. Taking this characteristic into account, we propose two new approaches (Speed-Partitioned Ordered Chain (SPOC) and Fastest-Node First (FNF)) to implement collective communication operations with reduced latency. We also investigate methods for deriving optimal trees for broadcast and multicast operations. H..

Efficient Collective Communication on Heterogeneous Networks of Workstations

: Networks of Workstations (NOW) have become an attractive alternative platform for high performance computing. Due to the commodity nature of workstations and interconnects and the multiplicity of vendors and platforms for NOW systems, the NOW environments are being gradually redefined as Heterogeneous Networks of Workstations (HNOW) environments. This paper presents a new framework for implementing collective communication operations (as defined by the Message Passing Interface (MPI) standard) efficiently for the emerging HNOW environments. We first classify different types of heterogeneity in HNOW and then focus on one important characteristic: communication capabilities of workstations. Taking this characteristic into account, we show that the algorithms such as the Binomial-tree based algorithms which are currently used for implementing collective operations are not efficient. We propose two new approaches (Speed-Partitioned Ordered Chain (SPOC) and Fastest-Node First (FNF)) to..

Review of Natural History, Benefits and Risk Factors Pediatric Liver Transplantation

Liver or hepatic transplantation (LT) is the replacement of a diseased liver with part or whole healthy liver from another person (allograft). Human liver transplants were first performed by Thomas Starzl in the United States and Roy Calne in Cambridge, England in 1963 and 1967, respectively. Liver transplantation is a viable treatment option for end-stage liver disease and acute liver failure. Pediatric patients account for about 12.5% of liver transplant recipients. The most commonly used technique is orthotopic transplantation, in which the native liver is removed and replaced by the donor organ in the same anatomic location as the original liver. Cirrhosis, or liver injury, is a common reason why adults need liver transplants and children with bile duct disease issues are often the candidates. Survival statistics depend greatly on the age of donor, age of recipient, skill of the transplant center, compliance of the recipient, whether the organ came from a living or cadaveric donor and overall health of the recipient. Survival rates improve almost yearly, due to improved techniques and medications