102 research outputs found
Performance Evaluation of Adaptive Scheduling Algorithm for Shared Heterogeneous Cluster Systems
Cluster computing systems have recently generated enormous interest for providing easily scalable and cost-effective parallel computing solution for processing large-scale applications. Various adaptive space-sharing scheduling algorithms have been proposed to improve the performance of dedicated and homogeneous clusters. But commodity clusters are naturally non-dedicated and tend to be heterogeneous over the time as cluster hardware is usually upgraded and new fast machines are also added to improve cluster performance. The existing adaptive policies for dedicated homogeneous and heterogeneous parallel systems are not suitable for such conditions. Most of the existing adaptive policies assume a priori knowledge of certain job characteristics to take scheduling decisions. However such information is not readily available without incurring great cost. This paper fills these gaps by designing robust and effective space-sharing scheduling algorithm for non-dedicated heterogeneous cluster systems, assuming no job characteristics to reduce mean job response time. Evaluation results show that the proposed algorithm provide substantial improvement over existing algorithms at moderate to high system utilizations
ReSHAPE: A Framework for Dynamic Resizing and Scheduling of Homogeneous Applications in a Parallel Environment
Applications in science and engineering often require huge computational
resources for solving problems within a reasonable time frame. Parallel
supercomputers provide the computational infrastructure for solving such
problems. A traditional application scheduler running on a parallel cluster
only supports static scheduling where the number of processors allocated to an
application remains fixed throughout the lifetime of execution of the job. Due
to the unpredictability in job arrival times and varying resource requirements,
static scheduling can result in idle system resources thereby decreasing the
overall system throughput. In this paper we present a prototype framework
called ReSHAPE, which supports dynamic resizing of parallel MPI applications
executed on distributed memory platforms. The framework includes a scheduler
that supports resizing of applications, an API to enable applications to
interact with the scheduler, and a library that makes resizing viable.
Applications executed using the ReSHAPE scheduler framework can expand to take
advantage of additional free processors or can shrink to accommodate a high
priority application, without getting suspended. In our research, we have
mainly focused on structured applications that have two-dimensional data arrays
distributed across a two-dimensional processor grid. The resize library
includes algorithms for processor selection and processor mapping. Experimental
results show that the ReSHAPE framework can improve individual job turn-around
time and overall system throughput.Comment: 15 pages, 10 figures, 5 tables Submitted to International Conference
on Parallel Processing (ICPP'07
Efficient Algorithms for Scheduling Moldable Tasks
We study the problem of scheduling independent moldable tasks on
processors that arises in large-scale parallel computations. When tasks are
monotonic, the best known result is a -approximation
algorithm for makespan minimization with a complexity linear in and
polynomial in and where is
arbitrarily small. We propose a new perspective of the existing speedup models:
the speedup of a task is linear when the number of assigned
processors is small (up to a threshold ) while it presents
monotonicity when ranges in ; the bound
indicates an unacceptable overhead when parallelizing on too many processors.
For a given integer , let . In this paper, we propose a -approximation algorithm for makespan minimization with a
complexity where
(). As
a by-product, we also propose a -approximation algorithm for
throughput maximization with a common deadline with a complexity
Resource Provisioning Exploiting Cost and Performance Diversity within IaaS Cloud Providers
IaaS platforms such as Amazon EC2 allow clients access to massive computational power in the form of instances. Amazon hosts three different instance purchasing options, each with its own SLA covering pricing and availability. Amazon also offers access to a number of geographical regions, zones, and instance types to select from. In this thesis, the problem of utilizing Spot and On-Demand instances is analyzed and two approaches are presented in order to exploit the cost and performance diversity among different instance types and availability zones, and among the Spot markets they represent. We first develop RAMP, a framework designed to calculate the expected profit of using a specific Spot or On-Demand instance through an evaluation of instance reliability. RAMP is extended to develop RAMC-DC, a framework designed to allocate the most cost effective instance through strategies that facilitate interchangeability of instances among short jobs, reliability of instances among long jobs, and a comparison of the estimated costs of possible allocations. RAMC-DC achieves fault tolerance through comparisons of the price dynamics across instance types and availability zones, and through an examination of three basic checkpointing methods. Evaluations demonstrate that both frameworks take a large step toward low-volatility, high cost-efficiency resource provisioning. While achieving early-termination rates as low as 2.2%, RAMP can completely offset the total cost when charging the user just 17.5% of the On-Demand price. Moreover, the increases in profit resulting from relatively small additional charges to users are notably high, i.e., 100% profit compared to the resource provisioning cost with 35% of the equivalent On-Demand price. RAMC-DC can maintain deadline breaches below 1.8% of all jobs, achieve both early-termination and deadline breach rates as low as 0.5% of all jobs, and lowers total costs by between 80% and 87% compared to using only On-Demand instances
Resource Provisioning Exploiting Cost and Performance Diversity within IaaS Cloud Providers
IaaS platforms such as Amazon EC2 allow clients access to massive computational power in the form of instances. Amazon hosts three different instance purchasing options, each with its own SLA covering pricing and availability. Amazon also offers access to a number of geographical regions, zones, and instance types to select from. In this thesis, the problem of utilizing Spot and On-Demand instances is analyzed and two approaches are presented in order to exploit the cost and performance diversity among different instance types and availability zones, and among the Spot markets they represent. We first develop RAMP, a framework designed to calculate the expected profit of using a specific Spot or On-Demand instance through an evaluation of instance reliability. RAMP is extended to develop RAMC-DC, a framework designed to allocate the most cost effective instance through strategies that facilitate interchangeability of instances among short jobs, reliability of instances among long jobs, and a comparison of the estimated costs of possible allocations. RAMC-DC achieves fault tolerance through comparisons of the price dynamics across instance types and availability zones, and through an examination of three basic checkpointing methods. Evaluations demonstrate that both frameworks take a large step toward low-volatility, high cost-efficiency resource provisioning. While achieving early-termination rates as low as 2.2%, RAMP can completely offset the total cost when charging the user just 17.5% of the On-Demand price. Moreover, the increases in profit resulting from relatively small additional charges to users are notably high, i.e., 100% profit compared to the resource provisioning cost with 35% of the equivalent On-Demand price. RAMC-DC can maintain deadline breaches below 1.8% of all jobs, achieve both early-termination and deadline breach rates as low as 0.5% of all jobs, and lowers total costs by between 80% and 87% compared to using only On-Demand instances
Towards Optimality in Parallel Scheduling
To keep pace with Moore's law, chip designers have focused on increasing the
number of cores per chip rather than single core performance. In turn, modern
jobs are often designed to run on any number of cores. However, to effectively
leverage these multi-core chips, one must address the question of how many
cores to assign to each job. Given that jobs receive sublinear speedups from
additional cores, there is an obvious tradeoff: allocating more cores to an
individual job reduces the job's runtime, but in turn decreases the efficiency
of the overall system. We ask how the system should schedule jobs across cores
so as to minimize the mean response time over a stream of incoming jobs.
To answer this question, we develop an analytical model of jobs running on a
multi-core machine. We prove that EQUI, a policy which continuously divides
cores evenly across jobs, is optimal when all jobs follow a single speedup
curve and have exponentially distributed sizes. EQUI requires jobs to change
their level of parallelization while they run. Since this is not possible for
all workloads, we consider a class of "fixed-width" policies, which choose a
single level of parallelization, k, to use for all jobs. We prove that,
surprisingly, it is possible to achieve EQUI's performance without requiring
jobs to change their levels of parallelization by using the optimal fixed level
of parallelization, k*. We also show how to analytically derive the optimal k*
as a function of the system load, the speedup curve, and the job size
distribution.
In the case where jobs may follow different speedup curves, finding a good
scheduling policy is even more challenging. We find that policies like EQUI
which performed well in the case of a single speedup function now perform
poorly. We propose a very simple policy, GREEDY*, which performs near-optimally
when compared to the numerically-derived optimal policy
Reliable Provisioning of Spot Instances for Compute-intensive Applications
Cloud computing providers are now offering their unused resources for leasing
in the spot market, which has been considered the first step towards a
full-fledged market economy for computational resources. Spot instances are
virtual machines (VMs) available at lower prices than their standard on-demand
counterparts. These VMs will run for as long as the current price is lower than
the maximum bid price users are willing to pay per hour. Spot instances have
been increasingly used for executing compute-intensive applications. In spite
of an apparent economical advantage, due to an intermittent nature of biddable
resources, application execution times may be prolonged or they may not finish
at all. This paper proposes a resource allocation strategy that addresses the
problem of running compute-intensive jobs on a pool of intermittent virtual
machines, while also aiming to run applications in a fast and economical way.
To mitigate potential unavailability periods, a multifaceted fault-aware
resource provisioning policy is proposed. Our solution employs price and
runtime estimation mechanisms, as well as three fault tolerance techniques,
namely checkpointing, task duplication and migration. We evaluate our
strategies using trace-driven simulations, which take as input real price
variation traces, as well as an application trace from the Parallel Workload
Archive. Our results demonstrate the effectiveness of executing applications on
spot instances, respecting QoS constraints, despite occasional failures.Comment: 8 pages, 4 figure
Priority-enabled Scheduling for Resizable Parallel Applications
In this paper, we illustrate the impact of dynamic resizability on parallel scheduling.
Our ReSHAPE framework includes an application scheduler that supports dynamic resizing of parallel applications. We propose and evaluate new scheduling policies made possible by our ReSHAPE framework. The framework also provides a platform to experiment with more interesting and sophisticated scheduling policies and scenarios for resizable parallel applications. The proposed policies support scheduling of parallel applications with and without user assigned priorities. Experimental results show that these scheduling policies significantly improve individual application turn around time as well as overall cluster utilization
Co-scheduling algorithms for high-throughput workload execution
International audienceThis paper investigates co-scheduling algorithms for processing a set of parallel applications. Instead of executing each application one by one, using a maximum degree of parallelism for each of them, we aim at scheduling several applications concurrently. We partition the original application set into a series of packs, which are executed one by one. A pack comprises several applications, each of them with an assigned number of processors, with the constraint that the total number of processors assigned within a pack does not exceed the maximum number of available processors. The objective is to determine a partition into packs, and an assignment of processors to applications, that minimize the sum of the execution times of the packs. We thoroughly study the complexity of this optimization problem , and propose several heuristics that exhibit very good performance on a variety of workloads, whose application execution times model profiles of parallel scientific codes. We show that co-scheduling leads to faster workload completion time (40% improvement on average over traditional scheduling) and to faster response times (50% improvement). Hence co-scheduling increases system throughput and saves energy, leading to significant benefits from both the user and system perspectives
Power-Aware Job Dispatching in High Performance Computing Systems
This works deals with the power-aware job dispatching problem in supercomputers; broadly speaking the dispatching consists of assigning finite capacity resources to a set of activities, with a special concern toward power and energy efficient solutions. We introduce novel optimization approaches to address its multiple aspects.
The proposed techniques have a broad application range but are aimed at applications in the field of High Performance Computing (HPC) systems.
Devising a power-aware HPC job dispatcher is a complex, where contrasting goals must be satisfied. Furthermore, the online nature of the problem request that solutions must be computed in real time respecting stringent limits. This aspect historically discouraged the usage of exact methods and favouring instead the adoption of heuristic techniques. The application of optimization approaches to the dispatching task is still an unexplored area of research and can drastically improve the performance of HPC systems.
In this work we tackle the job dispatching problem on a real HPC machine, the Eurora supercomputer hosted at the Cineca research center, Bologna. We propose a Constraint Programming (CP) model that outperforms the dispatching software currently in use. An essential element to take power-aware decisions during the job dispatching phase is the possibility to estimate jobs power consumptions before their execution. To this end, we applied Machine Learning techniques to create a prediction model that was trained and tested on the Euora supercomputer, showing a great prediction accuracy. Then we finally develop a power-aware solution, considering the same target machine, and we devise different approaches to solve the dispatching problem while curtailing the power consumption of the whole system under a given threshold. We proposed a heuristic technique and a CP/heuristic hybrid method, both able to solve practical size instances and outperform the current state-of-the-art techniques
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