Richard R. Treumann

MPI-IO/GPFS, an Optimized Implementation of MPI-IO on Top of GPFS

MPI-IO/GPFS is an optimized prototype implementation of the I/O chapter of the Message Passing Interface (MPI) 2 standard. It uses the IBM General Parallel File System (GPFS) Release 3 as the underlying file system. This paper describes optimization features of the prototype that take advantage of new GPFS programming interfaces. It also details how collective data access operations have been optimized by minimizing the number of messages exchanged in sparse accesses and by increasing the overlap of communication with file access. Experimental results show a performance gain. A study of the impact of varying the number of tasks running on the same node is also presented.

Power shifting in Thrifty Interconnection Network

This paper presents two complementary techniques to manage the power consumption of large-scale systems with a packet-switched interconnection network. First, we propose Thrifty Interconnection Network (TIN), where the network links are activated and de-activated dynamically with little or no overhead by using inherent system events to timely trigger link activation or de-activation. Second, we propose Network Power Shifting (NPS) that dynamically shifts the power budget between the compute nodes and their corresponding network components. TIN activates and trains the links in the interconnection network, just-in-time before the network communication is about to happen, and thriftily puts them into a low-power mode when communication is finished, hence reducing unnecessary network power consumption. Furthermore, the compute nodes can absorb the extra power budget shifted from its attached network components and increase their processor frequency for higher performance with NPS. Our simulation results on a set of real-world workload traces show that TIN can achieve on average 60% network power reduction, with the support of only one low-power mode. When NPS is enabled, the two together can achieve 12% application performance improvement and 13% overall system energy reduction. Further performance improvement is possible if the compute nodes can speed up more and fully utilize the extra power budget reinvested from the thrifty network with more aggressive cooling support.

Towards a High-Performance Implementation of MPI-IO on Top of GPFS

MPI-IO/GPFS is a prototype implementation of the I/O chapter of the Message Passing Interface (MPI) 2 standard. It uses the IBM General Parallel File System (GPFS) as the underlying file system. This paper describes the features of this prototype which support its high performance. The use of hints allows tailoring the use of the file system to the application needs.

Thrifty interconnection network for HPC systems

We propose Thrifty Interconnection Network (TIN), where the network links are activated and de-activated dynamically to save power with little or no overhead by using inherent system events to overlap the link activation or de-activation time. Our simulation results on a set of real world HPC workload traces show on average 35% network power reduction.