Optimization of Discrete-parameter Multiprocessor Systems using a Novel Ergodic Interpolation Technique

Modern multi-core systems have a large number of design parameters, most of which are discrete-valued, and this number is likely to keep increasing as chip complexity rises. Further, the accurate evaluation of a potential design choice is computationally expensive because it requires detailed cycle-accurate system simulation. If the discrete parameter space can be embedded into a larger continuous parameter space, then continuous space techniques can, in principle, be applied to the system optimization problem. Such continuous space techniques often scale well with the number of parameters. We propose a novel technique for embedding the discrete parameter space into an extended continuous space so that continuous space techniques can be applied to the embedded problem using cycle accurate simulation for evaluating the objective function. This embedding is implemented using simulation-based ergodic interpolation, which, unlike spatial interpolation, produces the interpolated value within a single simulation run irrespective of the number of parameters. We have implemented this interpolation scheme in a cycle-based system simulator. In a characterization study, we observe that the interpolated performance curves are continuous, piece-wise smooth, and have low statistical error. We use the ergodic interpolation-based approach to solve a large multi-core design optimization problem with 31 design parameters. Our results indicate that continuous space optimization using ergodic interpolation-based embedding can be a viable approach for large multi-core design optimization problems.Comment: A short version of this paper will be published in the proceedings of IEEE MASCOTS 2015 conferenc

An evaluation of a microprocessor with two independent hardware execution threads coupled through a shared cache

We investigate the utility of augmenting a microprocessor with a single execution pipeline by adding a second copy of the execution pipeline in parallel with the existing one. The resulting dual-hardware-threaded microprocessor has two identical, independent, single-issue in-order execution pipelines (hardware threads) which share a common memory sub-system (consisting of instruction and data caches together with a memory management unit). From a design perspective, the assembly and verification of the dual threaded processor is simplified by the use of existing verified implementations of the execution pipeline and a memory unit. Because the memory unit is shared by the two hardware threads, the relative area overhead of adding the second hardware thread is 25\% of the area of the existing single threaded processor. Using an FPGA implementation we evaluate the performance of the dual threaded processor relative to the single threaded one. On applications which can be parallelized, we observe speedups of 1.6X to 1.88X. For applications that are not parallelizable, the speedup is more modest. We also observe that the dual threaded processor performance is degraded on applications which generate large numbers of cache misses

The Purification and Partial Characterization of the Surface Polysaccharides from Three Fast-Growing Rhizobium japonicum Strains

The fast-growing strains of R. japonicum were originally isolated from China. They are acid-producing Rhizobia and are capable of nodulating soybeans. These isolates share a common host-specificity (Peking soybean) with the slow-growing R. japonicum strains even though their biochemical properties are more closely related to other fast-growing Rhizobium species. The surface polysaccharides from three fast-growing R. japonicum strains--USDA201, USDA205, and HC205--were isolated and partially characterized. Strain HC205 is a nod⁻ mutant of USDA205 which lacks the symbiotic plasmid. These surface polysaccharides consist of extracellular, capsular and lipopolysaccharides (EPSs, CPSs and LPSs). The EPSs from all three strains are very similar in composition having galactose, glucose, uronic acid and acetate. These components are similar to the EPSs from other fast-growing Rhizobium species except for pyruvate which is not detected in the EPSs from fast-growing R. japonicum strains. The CPSs from USDA205 and HC205 are very similar to the EPSs in composition except they contain increased amounts of acetate. The CPS from USDA201 is isolated in very small amounts and is different in composition from the EPSs in that it is reduced in glucose and increased in uronic acid. The EPSs and CPSs are different from those of the slow-growing R. japonicum strains which vary from strain to strain and can consist of methylated sugars and deoxysugars. The LPSs were purified by phenol/water extraction and gel filtration chromatography. The LPSs from USDA205 and HC205 elute as broad peaks from the gel filtration column and contain 2-keto-3-deoxyoctonic acid (KDO) as one of the major sugar components. The LPS from HC205 differs from that of USDA205 in that it contains ribose. Both USDA205 and HC205 LPSs have a lamba max at 260 nm. Both the ribose content and the lamba max at 260 nm are resistant to RNase treatment. Gel-filtration of the phenol/water extracted polysaccharides from USDA201 results in two distinct KDO containing peaks (LPS1 and LPS2). Both LPS1 and LPS2 have similar compositions containing ribose, 2,3-di-O-methyl-hexose, galactose, glucose and KDO. Again KDO is a major sugar, LPS2 having the largest amount of KDO. None of the LPSs contain heptose. The presence of KDO as a major sugar in the LPSs makes these LPS different from the phenol/water extracted polysaccharides of the slow-growing R. japonicum strains which do not contain detectable levels of KDO, and different from the LPSs from other fast-growing Rhizobium species which contain 1-5% KDO. The LPSs from R. meliloti strains are other LPSs in which KDO is a major sugar. Polyacrylamide gel electrophoresis shows that the LPS are typically heterogeneous molecules. Differences in banding patterns are observed among the fast-growing R. japonicum LPSs as well as the differences between these LPSs and other fast-growing Rhizobium LPSs

DIGITAL HUMANITIES IN INDIA: A DEVELOPING COUNTRY PERSPECTIVE

The buzzword Digital Humanities (DH) is gaining attention in developing country like India. The activities so far undertaken in India includes organization of conferences on Digital Humanities and offering of post graduate courses by some institutions and Universities. The DH activity is confined to specific states of India only. The role of Library & Information Science (LIS) professionals is negligible. Still defining DH is a problem. There is a need of collaboration between DH specialist and LIS professionals to foster DH development in India. This paper will overview DH developments in India