Rodrigo da Rosa Righi

MigBSP: A Novel Migration Model for Bulk-Synchronous Parallel Processes Rescheduling

We have developed a model called MigBSP that controls processes rescheduling in BSP (Bulk Synchronous Parallel)applications. A BSP application is composed by one or more supersteps, each one containing both computation and communication phases followed by a synchronization barrier. Since the barrier waits for the slowest process, MigBSP’s final idea is to adjust the processes location in order to reduce the supersteps’ times. Considering the scope of the BSP model, the novel ideas of MigBSPare: (i) combination of three metrics - Memory, Computation and Communication - to measure the potential of migration of each BSP process; (ii) use of both Computation and Communication Patterns to control processes’ regularity;(iii) adaptation regarding the periodicity to launch the processes rescheduling. This paper describes MigBSP and presents some experimental results and related work.

OBSERVING THE IMPACT OF MULTIPLE METRICS AND RUNTIME ADAPTATIONS ON BSP PROCESS RESCHEDULING

Process rescheduling is an useful mechanism to offer runtime load balancing, mainly in dynamic and heterogeneous environments. In this context, we developed a model called MigBSP which controls the process migration on BSP (Bulk Synchronous Parallel) applications. A BSP application is divided in one or more supersteps, each one containing both computation and communication phases followed by a barrier synchronization. Since the barrier waits for the slowest process, MigBSPs final objective is to adjust the processes location in order to reduce the supersteps times. Its novel ideas are twofold. The former is represented by the combination of three metrics - Memory, Computation and Communication - in order to measure the Potential of Migration of each BSP process. The second idea consists in offering efficient adaptations that work on the rescheduling frequency. Both ideas turn MigBSP a viable model for getting performance on BSP applications. Meanwhile, it provides a low overhead on application execution when migrations do not take place. This paper presents MigBSPs algorithms, the parallel machine organization, some experimental results and related work.

jMigBSP: Object Migration and Asynchronous One-Sided Communication for BSP Applications

This paper describes the rationale for developing jMigBSP - a Java programming library that offers object rescheduling. It was designed to work on grid computing environments and offers an interface that follows the BSP (Bulk Synchronous Parallel) style. jMigBSPs main contribution focuses on the rescheduling facility in two different ways: (i) by using migration directives on the application code directly and (ii) through automatic load balancing at middleware level. Especially, this second idea is feasible thanks to the Javas inheritance feature, in which transforms a simple jMigBSP application in a migratable one only by changing a single line of code. In addition, the presented library makes the object interaction easier by providing one-sided message passing directives and hides network latency through asynchronous communications. Finally, a BSP-based FFT application was developed and its execution shows jMigBSP as a competitive library when comparing performance with a C-based library called BSPlib. Besides its user-friendly Java interface, the strengths of jMigBSP also considers the migration tests where it outperforms the time spent with BSPlib.

Applying Processes Rescheduling over Irregular BSP Application

This paper shows an evaluation of processes rescheduling over an irregular BSP (Bulk Synchronous Parallel) application. Such application is based on dynamic programming and its irregularity is presented through the variation of computation density along the matrix cells. We are using MigBSP model for processes rescheduling, which combines multiple metrics - Computation, Communication and Memory - to decide about processes migration. The main contribution of this paper includes the viability to use processes migration on irregular BSP applications. Instead to adjust the load of each process by hand, we presented that automatic processes rebalancing is an effortless technique to obtain performance. The results showed gains greater than 10% over our multi-cluster architecture. Moreover, an acceptable overhead from MigBSP was observed when no migrations happen during application execution.

Asynchronous communication in Java over Infiniband and DECK

Java is becoming an attractive and easy to use programming language. It provides two systems for distributed computing, RMI and sockets, which describe a synchronous communication over TCP/IP. These Java core features may not be the best choice for cluster computing environments, since they do not provide high performance, a critical factor in this scenario. In this paper, presented is the development of Aldeia system, a library proposal to provide asynchronous communication in Java for cluster programming. Aldeia has been deployed on SAN hardware through Infiniband and DECK high-speed substrates. This paper shows the rationale for Aldeias creation, its structure and encouraging results in synchronous and asynchronous approaches.

Design of a Grid workflow for a climate application

Grid applications can be modeled as a composition of rather independent tasks. There are two approaches to define such a workflow either by combining multiple applications to build a more complex functionality or by splitting up an existing application. In this paper we analyze the latter process. We present a compute intensive application for climatology simulation and the options available to split it up. Using the simulation mode of our Grid broker, we were able to compare the different workflow specifications before actually executing the workflows. This case study showed, using finer grained workflows—which usually need more adjustments to the software—allows better performance in the Grid.

Process Rescheduling in High Performance Computing Environments

Scheduling is an important tool for manufacturing and engineering, where it can have a major impact on the productivity of a process (Min et al., 2009). In manufacturing, the purpose of production scheduling is to minimize the production time and costs, by informing a production facility when to make, with which staff, and on which equipment (Zhu et al., 2011). Nowadays, it is possible to observe the use of specific computational tools for production scheduling in which greatly outperform older manual scheduling methods. These tools implement mathematical programming methods that model the problem as an optimization issue where some objective, e.g. total duration, must be minimized (or yet maximized) (Yao & Zhu, 2010).

Combining Multiple Metrics to Control BSP Process Rescheduling in Response to Resource and Application Dynamics

This article discusses MigBSP: a rescheduling model that acts on Bulk Synchronous Parallel applications running over computational Grids. It combines the metrics Computation, Communication and Memory to make migration decisions. MigBSP also offers efficient adaptations to reduce its overhead. Additionally, MigBSP is infrastructure and application independent and tries to handle dynamicity on both levels. MigBSPs results show application performance improvements of up to 16% on dynamic environments while maintaining a small overhead when migrations do not take place.

Process Migration: Controlling Application and Resource Dynamics by Combining Computation, Communication and Memory Metrics

In this paper we present MigBSP, a rescheduling mo- del that acts on Bulk Synchronous Parallel applications. It combines the metrics Computation, Communication and Memory to make migration decisions on Computation Grids. MigBSP also offers efficient adaptations to reduce its own overhead. Additionally, MigBSP is infrastructure and application independent and tries to handle dynamicity on both levels. MigBSPs results show performance gains of up to 16% on dynamic environments while maintaining a small overhead when migrations do not take place.

Supporting performance and adaptivity on BSP process rescheduling

In this paper we will describe a model for BSP (Bulk Synchronous Parallel) process rescheduling called MigBSP. Considering the scope of BSP applications, its differential approach is the combination of three metrics - Memory, Computation and Communication - in order to measure the Potential of Migration of each BSP process. In this context, this paper addresses both the efficiency and the adaptivity perspectives of this model over our multi-cluster machine.