Use of Architectural Simulation Tools in Education

This paper presents the author’s experience in using architectural simulation tools in the instruction of computer architecture courses. In particular, we develop the notion of incrementally building a programmable, trace–driven “timer ” tool, for use as a learning vehicle. We show how the cycle– by–cycle simulation output of such timers can be used to illustrate performance bottlenecks, and how this and other output statistics can be interpreted to convey key design tuning issues. As part of the overall simulation toolkit, we also use available cache simulators, trace generators and other utilities in illustrating key performance determinants and architectural trade–off issues. Undergraduate or beginning graduate courses in computer architecture, such as those based on the well–known texts by Hennessey and Patterson [1, 2] often use a simple processor, e.g. DLX [1] as a running example to develop and illustrate key machine design concepts. Projects and assignments centered around the example processor, are crafted to enable the student to grasp alternate design an

Systematic energy characterization of CMP/SMT processor systems via automated micro-benchmarks

Microprocessor-based systems today are composed of multi-core, multi-threaded processors with complex cache hierarchies and gigabytes of main memory. Accurate characterization of such a system, through predictive pre-silicon modeling and/or diagnostic postsilicon measurement based analysis are increasingly cumbersome and error prone. This is especially true of energy-related characterization studies. In this paper, we take the position that automated micro-benchmarks generated with particular objectives in mind hold the key to obtaining accurate energy-related characterization. As such, we first present a flexible micro-benchmark generation framework (MicroProbe) that is used to probe complex multi-core/multi-threaded systems with a variety and range of energy-related queries in mind. We then present experimental results centered around an IBM POWER7 CMP/SMT system to demonstrate how the systematically generated micro-benchmarks can be used to answer three specific queries: (a) How to project application-specific (and if needed, phase-specific) power consumption with component-wise breakdowns? (b) How to measure energy-per-instruction (EPI) values for the target machine? (c) How to bound the worst-case (maximum) power consumption in order to determine safe, but practical (i.e. affordable) packaging or cooling solutions? The solution approaches to the above problems are all new. Hardware measurement based analysis shows superior power projection accuracy (with error margins of less than 2.3% across SPEC CPU2006) as well as max-power stressing capability (with 10.7% increase in processor power over the very worst-case power seen during the execution of SPEC CPU2006 applications).Peer ReviewedPostprint (author’s final draft

Siliciclastic–carbonate mixing modes in the river-mouth bar palaeogeography of the Upper Cretaceous Garudamangalam Sandstone (Ariyalur, India)

AbstractMixed siliciclastic–carbonate rocks constitute the Upper Cretaceous Garuda-mangalam Sandstone Formation, Ariyalur (India), and offer an opportunity to look into the broad spectrum of mixing of compositionally and genetically different components. The palaeogeographic reconstruction indicates that deposition in the nearshore zone differed strongly in energy and active processes operatives due to the presence of a shore-parallel river-mouth bar. The western wing of the Mississippi bird-foot delta is considered to be a present-day analogon. Facies analysis in combination with petrography clearly shows the variability in palaeoenvironmental characteristics, both biogenic and non-biogenic. It also indicates diagenetic uptake of carbonate that filled empty spaces and actively replaced original components. Chemical staining followed by limited application of cathodoluminescence and energy dispersive X-ray analysis (EDAX) hint at intricacies in mixing arising from the compositional variations in the carbonate components. A model of siliciclastic–carbonate sediment mixing, including both the depositional and diagenetic developments, is presented; it is aimed at generating a better overview of, and a deeper insight into, the physical and chemical mechanisms involved

Adaptive power shifting for power-constrained heterogeneous systems

The number and heterogeneity of compute devices, even within a single compute node, has been steadily on the rise. Since all systems must operate under a power cap, the number of discrete devices that can run simultaneously at their highest frequency is limited by the globally-imposed power cap. Current systems incorporate a centralized power management unit that statically controls the distribution of power among the devices within the node. However, such static distribution policies are unaware of the dynamic utilization profile across the devices, which leads to unfair power allocations that end up degrading system throughput performance. The problem is particularly acute in the presence of heterogeneity since type-specific performance-boost capabilities cannot be leveraged via utilization-agnostic static power allocations. This paper proposes Adaptive Power Shifting for multi-accelerator heterogeneous systems (APS), a technique that leverages system utilization information to dynamically allocate and re-distribute power budgets across multiple discrete devices. Democratizing the power allocation based on dynamic needs results in dramatic speedup over a need-agnostic static allocation. We use APS in a real OpenPOWER compute node with 2 CPUs and 4 GPUs to demonstrate the value of on-demand, equitable power allocations. Overall, the proposed solution increases performance with respect to two state-of-the-art techniques by up to 14.9% and 13.8%.This work has been partially supported by the European Union’s Horizon 2020 research and innovation program under the Mont-Blanc 2020 project (grant agreement 779877), by the Spanish Ministry of Science and Innovation (contract PID2019-107255GB-C22), by Generalitat de Catalunya (contracts 2014-SGR-1051 and 2014-SGR-1272) and by the IBM/BSC Deep Learning Center initiative. Ll. Alvarez has been supported in part by the Spanish Ministry of Economy, Industry and Competitiveness under the Juan de la Cierva Formacion fellowship No. FJCI-2016- 30984. M. Moreto has been supported in part by the Spanish Ministry of Economy, Industry and Competitiveness under Ramon y Cajal fellowship No. RYC-2016-21104.Peer ReviewedPostprint (author's final draft

A Multi-centre Study to Evaluate the Long-Term Efficacy and Safety of Biosimilar Infliximab (Infimab™) in Ankylosing Spondylitis in Real-world Clinical Settings - A perspective from Eastern India

Introduction: Owing to dearth of data on infliximab biosimilars in Indian patients, a pan-India case database-based study with infliximab biosimilar BOW015 (Infimab™) was carried out to capture its efficacy and safety in real world clinical settings in India. Here, we assessed its efficacy and safety in ankylosing spondylitis (AS) among patients in the East India cohort. Materials and methods: Data were collected from multiple centers across the eastern region of India. Patients diagnosed with AS, within the preceding 4-6 months during the preceding one year were included in the study. Patients who were given BOW015 for other indications, prior innovator infliximab or other biologics were excluded from the study. Primary variable was Ankylosing Spondylitis Disease Activity Scale (ASDAS) response defined as change of > 2 in the ASDAS score from the baseline by 4-6 months of follow up. Results: The cohort consisted of 149 patients, predominantly male (69.8%), with mean (±SD) age of 36.75 (±11.11) years and mean (±SD) body weight of 58.26 (±15.4) kgs. Of the treated patients, 91 (61.1%) patients were administered four doses, 10 (6.7%) patients were administered three doses, 37 (24.8%) patients were administered two doses and 11 (7.4%) patients were administered only a single dose of BOW015. In the final analysis set, 81 patients had data at baseline and 4th visit. Among the 81 patients, 74 (91%) patients achieved major improvement, 5 (6%) patients achieved clinically important improvement and 2 (3%) were non-responders at 4th visit. Secondarily, cross categorization of the cohort into disease activity categories by number of infusions administered from baseline to 4th visit and assessment of trends in Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores were also carried out and these too confirmed the efficacy of BOW015. Conclusion: Infimab™ (BOW015) showed significant improvement in ASDAS and BASDAI in patients with AS at the end of 4-6 months of follow up with its clinical benefits being apparent as early as first dose of BOW015

Performance and Power Evaluation of an In-line Accelerator

ABSTRACT In this paper we evaluate the performance and power of a processor-attached in-line accelerator. The accelerator provides high-performance SIMD computing and power efficiency by means of a very large register file and a set of vector multimedia extensions based on IBM's PowerPC VMX. Our experiments show significant performance improvements and power reduction, compared to a baseline vector execution unit, mainly due to the drastic decrease of memory accesses caused by the software-managed locality of the very large register file. Total execution time is, on average, reduced by 61%, while consuming 55% less energy