Evolution of thread-level parallelism in desktop applications

As the effective limits of frequency and instruction level par-allelism have been reached, the strategy of microprocessor vendors has changed to increase the number of processing cores on a single chip each generation. The implicit expecta-tion is that software developers will write their applications with concurrency in mind to take advantage of this sudden change in direction. In this study we analyze whether soft-ware developers for laptop/desktop machines have followed the recent hardware trends by creating software for chip multi-processing. We conduct a study of a wide range of ap-plications on Microsoft Windows 7 and Apple’s OS X Snow Leopard, measuring Thread Level Parallelism on a high per-formance workstation and a low power desktop. In addition, we explore graphics processing units (GPUs) and their im-pact on chip multi-processing. We compare our findings to a study done 10 years ago which concluded that a second core was sufficient to improve system responsiveness. Our results on today’s machines show that, 10 years later, surprisingly 2-3 cores are more than adequate for most applications and that the GPU often remains under-utilized. However, in some application specific domains an 8 core SMT system with a 240 core GPU can be effectively utilized. Overall these studies suggest that many-core architectures are not a natural fit for current desktop/laptop applications