2014, Vol.19, No.4

Journal of The Korea Society of Computer and Information 2023 KCI Impact Factor : 0.65

pISSN : 1598-849X / eISSN : 2383-9945
https://journal.kci.go.kr/jksci

As cores in multi-core processors are integrated in a single chip, power density increasedconsiderably, resulting in high temperature. For this reason, many research groups have focused on the techniques to solve thermal problems. In general, the approaches using mechanical coolingsystem or DTM(Dynamic Thermal Management) have been used to reduce the temperature in themicroprocessors. However, existing approaches cannot solve thermal problems due to high cost andperformance degradation. However, floorplan scheme does not require extra cooling cost andperformance degradation. In this paper, we propose the diverse floorplan schemes in order toalleviate the thermal problem caused by the hottest unit in multi-core processors. Simulationresults show that the peak temperature can be reduced efficiently when the hottest unit is locatednear to L2 cache. Compared to baseline floorplan, the peak temperature of core-central andcore-edge are decreased by 8.04℃, 8.05℃ on average, respectively.

This paper proposes a linear scratch detection and restoration algorithm using pixel datacomparison in a single frame or consecutive frames. There exists a high parallelism in that ascratch detection and restoration algorithm needs a large amount of comparison operations. Theproposed scratch detection and restoration algorithm is designed with a GPU for fast computation. We test the proposed algorithm in sequential and parallel processing with the set of digital videosin National Archive of Korea. In the experiments, the scratch detection rate of consecutive framesis as fast as about 20% for that of a single frame. The detection and restoration rates of a GPU-based algorithm are similar to those of a CPU-based algorithm, but the parallelimplementation speeds up to about 50 times.

Detecting data races is important for debugging shared-memory programs with nestedparallelism, because races result in unintended non-deterministic executions of the program. It isespecially important to detect the first occurred data races for effective debugging, because theremoval of such races may make other affected races disappear or appear. Previous dynamicdetection tools for first race detecting can not guarantee that detected races are unaffected races. Also, the tools does not consider the nesting levels or need support of other techniques. This papersuggests a post-mortem tool which collects candidate accesses during program execution and then detects the first races to occur on the program after execution. This technique is efficient, becauseit guarantees that first races reported by analyzing a nesting level are the races that occur first atthe level, and does not require more analyses to the higher nesting levels than the current level.