Locality-Based Cache Management and Warp Scheduling for Reducing Cache Contention in GPU

GPGPUs has gradually become a mainstream acceleration component in high-performance computing. The long latency of memory operations is the bottleneck of GPU performance. In the GPU, multiple threads are divided into one warp for scheduling and execution. The L1 data caches have little capacity, while multiple warps share one small cache. That makes the cache suffer a large amount of cache contention and pipeline stall. We propose Locality-Based Cache Management (LCM), combined with the Locality-Based Warp Scheduling (LWS), to reduce cache contention and improve GPU performance. Each load instruction can be divided into three types according to locality: only used once as streaming data locality, accessed multiple times in the same warp as intra-warp locality, and accessed in different warps as inter-warp data locality. According to the locality of the load instruction, LWS applies cache bypass to the streaming locality request to improve the cache utilization rate, extend inter-warp memory request coalescing to make full use of the inter-warp locality, and combine with the LWS to alleviate cache contention. LCM and LWS can effectively improve cache performance, thereby improving overall GPU performance. Through experimental evaluation, our LCM and LWS can obtain an average performance improvement of 26% over baseline GPU.

Effects of Design Parameter on Occurrence of Snap Load and Wear of Mooring Line for Spar-Buoy With Ring-Fin Motion Stabilizer for Shallow Sea

The purpose of this study is to propose an optimal design method of the spar-buoy with ring-fin motion stabilizer for shallow sea and its mooring system, in order to avoid the occurrence of snap load. The mechanism of occurrence of snap load is investigated by model tests, and design parameters for avoiding the occurrence of snap load are investigated. From the observation of model’s motion, it has been realized that the snap load is caused by the tension of mooring line to stop the buoy’s horizontal motion, which relaxes the mooring line. Moreover, it has been confirmed that the horizontal motion is caused by the horizontal forces acting on the center pipe and float of the buoy, which relates to the acceleration component of wave excitation forces. In this paper, the effects of changing of design of the buoy (: diameter of center pipe and float, size of stabilizer, density of the buoy, length of mooring line) on avoiding or reducing snap load are investigated by using a numerical simulation (OrcaFlexver.11.0b), and the wear amounts are also estimated by using an empirical method (Takeuchi et al., 2019). From the results, it is confirmed that changing the buoy’s motion mode by shortening mooring line is effective to avoiding the occurrence of snap load, and to reduce the wear amount of the mooring line.

Approbation of the Method for Examining the Performance of Seafloor Observatory Sensors Using Distant Earthquakes Records

An algorithm is presented for testing the calibration accuracy of both z-accelerometers and pressure gauges (PG) installed in seafloor observatories. The test is based on the linear relationship between the vertical acceleration component of the seafloor movement and variations of the seafloor pressure, which is a direct consequence of Newton's 2-nd law and holds valid in the frequency range of “forced oscillations.” The operability of the algorithm is demonstrated using signals registered by 28 observatories of the DONET-2 system during 4 earthquakes of magnitude Mw ~ 8 that took place in 2018-2019 at epicentral distances from 55° up to 140°.

Design of a Coriolis Acceleration Experimental Device

Important drawbacks of Coriolis experimental setup and devices are their multiple parts and cost to own. Simplicity, traceability, and measurability are the major concern. This paper presents a preliminary design process of Coriolis acceleration experimental device to visualize the effect of Coriolis and enable the calculation of acceleration components to facilitate students for a better understanding of this phenomenon. This is realized through a slidable collar with a marker and accelerometer attached on it and a rotating rod that shows a visible yet erasable mark from the marker’s path. The design process went through typical engineering design processes such as morphological study, functional decomposition, and Pugh chart. Next, Finite Element Analyses (FEA) were performed to determine the mode shapes, followed by analytical calculation of the dynamic reaction experienced by motor. In addition, this kit provides opportunity for students to manually calculate the actual acceleration component based on theory learnt which is considered innovative. The use of controllable motor for rotating the rod could vary the travelling path of the marker, subsequently diversify the problems for student to solve.

Identification of the internal combustion engine malfunctions based on the vibrations of the vehicle body

Selected parameters of an IC engine were correlated with vibrations transferred to the vehicle body with the aim of identifying engine malfunctions. Registered acceleration component signals were analyzed in the aspect of frequency. A reasoning model based on devised identification matrix was used to classify obtained data. This allowed the authors to estimate the possibility of research object damage/malfunctions with an assumed degree of probability.

Measuring torque of galactic bar from Gaia DR2

Since past few decades, observations have improved so strongly that when modelling Milky Way (MW) dynamics it is required to include small perturbations to the modelling process. It is difficult task that we try to solve by selecting regions to model so small that the perturbation can be considered to give nearly constant effect. We use Solar Neighbourhood (SN) as our test sample and assume that the bar effects show more or less constant contribution to SN. By extrapolating and smoothing observed stars on their orbits, and requiring that smoothed and observed phase space are consistent we were able to deduce acceleration vector. We conclude from non-radial acceleration component that the bar must cause about one third of total acceleration near SN.

Materials and Techniques for Reduction of Vibration Transmission in String Trimmers

It has been well documented that over long periods of time, people who regularly operate hand tools powered by small internal-combustion engines can become affected by a debilitating set of clinically irreversible effects, collectively referred to as hand-arm vibration syndrome (HAVS). Although HAVS cannot be cured, the onset of the disorder can be delayed or, in fact, prevented, by restricting the duration of the exposure and/or the magnitude of the vibration transmitted from the tool to an operator’s hands and arms (per OSHA and similar standards). Measurements have confirmed that vibration components along all three tool coordinate directions (axial, radial and circumferential) are significant, but vary in amplitude and frequency content as a function of location. The challenge is to find passive approaches capable of filtering out the most harmful low frequency components simultaneously along all three directions that do not impede the use of the string trimmer. Preliminary results show that adding lightweight, low density (lodengraf) particles to the string trimmer along its shaft reduces the amplitude of the measured radial and axial acceleration components at the grip and the loop handle. However, when the perlite particles are added only to the loop handle, there is an increase in measured circumferential acceleration component at the grip, likely due to the additional weight asymmetry introduced.