The efficient support of cache coherence is extremely important to design and implement many-core processors. In this paper, we propose a synchronization-based coherence (SBC) protocol to efficiently support cache coherence for shared memory many-core architectures. The unique feature of our scheme is that it doesn’t use directory at all. Inspired by scope consistency memory model, our protocol maintains coherence at synchronization point. Within critical section, processor cores record write-sets (which lines have been written in critical section) with bloom-filter function. When the core releases the lock, the write-set is transferred to a synchronization manager. When another core acquires the same lock, it gets the write-set from the synchronization manager and invalidates stale data in its local cache. Experimental results show that the SBC outperforms by averages of 5% in execution time across a suite of scientific applications. At the mean time, the SBC is more cost-effective comparing to directory-based protocol that requires large amount of hardware resource and huge design verification effort.

On-chip many core architecture is an emerging and promising computation platform. High speed on-chip communication and abundant chipped resources are two outstanding advantages of this architecture, which provide an opportunity to implement efficient synchronization scheme. The practical execution efficiency of synchronization scheme is critical to this platform. However, there are few researches on systematic evaluation method of choice synchronization schemes for on-chip many core processors, and effect of dedicated hardware support in this context. So we focus on the evaluation method and criterion of synchronization scheme on the platform. Firstly, we present several criterions proper to on-chip many core architecture, that is, absolute overhead of synchronization operation, the transferring time between different synchronization operations, overhead caused by load imbalance, and the network congestion caused by synchronization operation. Secondly, we illustrate how to design microbenchmarks which one dedicated to evaluate a performance criterion respectively. Finally, we implement these microbenchmarks and synchronization schemes on an on-chip many core processor with shared level-two cache and AMD Opteron commercial chip multi-processor, respectively. And we analyze effect of dedicated hardware support. Results show that the most overhead of synchronization is caused by load imbalance and serialization on synchronization point. It also shows that synchronization scheme supported with dedicated hardware can improve its performance obviously for chipped many-core processor.

to date, most of many-core prototypes employ tiled topologies connected through on-chip networks. The throughput and latency of the on-chip networks usually become to the bottleneck to achieve peak performance especially for communication intensive applications. Most of studies are focus on on-chip networks only, such as routing algorithms or router micro-architecture, to improve the above metrics. The salient aspect of our approach is that we provide a data management framework to implement high efficient on-chip traffic based on overall many-core system. The major contributions of this paper include that: (1) providing a novel tiled many-core architecture which supports software controlled on-chip data storage and movement management; (2) identifying that the asynchronous bulk data transfer mechanism is an effective method to tolerant the latency of 2-D mesh on-chip networks. At last, we evaluate the 1-D FFT algorithm on the framework and the performance achieves 47.6 Gflops with 24.8% computation efficiency.

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No abstract available.

Range reduction is important in evaluating trigonometric functions but not enough work is done in relation to the hardware implementation of it. A hardware floating point range reduction implementation is presented. The whole reduction is divided into two steps; the first is based on double-residue modular range reduction method and the second adopts on a novel method described in this paper. The latter one can reduce the argument to an arbitrary range and provides the number of times that range constant contained in the argument. It has been synthesized using 0.13 mum library to achieve an approximately 700 MHz operation frequency.

This paper presents a framework for implementing the X86 FP stack used in an x86-compliant processor based on a general RISC architecture. Architectural supports are added to a typical RISC architecture to maintain the FP stack status. Some speculative techniques are applied to the decode stage to enable pipelined and efficient FP operations. An optimized register renaming scheme is proposed to eliminate redundant micro-ops in FP programs, resulting in an increased performance while mitigating the burden on register rename table. The simulation results show that on average more than 10% fmov micro-ops are removed. Elimination of micro-ops significantly speeds up the execution of programs. The IPC increases are as high as 30% for some programs, and near 10% on average