In multicore environment, multithreading is often used to improve application performance. However, even in many simple applications, the performance might degrade when the number of threads increases. Users usually i...In multicore environment, multithreading is often used to improve application performance. However, even in many simple applications, the performance might degrade when the number of threads increases. Users usually impute this phenomenon to the overhead of creation or termination of threads. In our observation, how the threads are dispatched to the multiple cores might have a more significant effect. We formally defined the problems on using threads as multithreading anomalies, and presented a novel user dispatching mechanism （UDispatch） which provides controllability in user space to improve application performance. Through modification of application source codes with the UDispatch application programming interface （API）, the application performance can be improved significantly. However, since the application source codes might not be available or it might be too complicated to modify application source codes, we provided an extension, called UDispatch＋, to dispatch threads without any modification of application source codes. In this paper, the UDispatch and UDispatch＋ are integrated and wrapped for more portability and introduced as a tool called Unified UDispatch （UUD） with more detailed experiments and description. It can dispatch the application threads to specific cores at the discretion of users with up to 171.8% performance improvement on a 4-core machine.展开更多
With the growing popularity of 3G-powered devices, there are growing demands on energy-efficient data trans- mission strategies for various embedded systems. Different from the past work in energy-efficient real-time ...With the growing popularity of 3G-powered devices, there are growing demands on energy-efficient data trans- mission strategies for various embedded systems. Different from the past work in energy-efficient real-time task scheduling, we explore strategies to maximize the amount of data transmitted by a 3G module under a given battery capacity. In particular, we present algorithms under different workload configurations with and without timing constraint considerations. Experiments were then conducted to verify the validity of the strategies and develop insights in energy-efficient data transmission.展开更多
基金supported in part by the "National Science Council",Taiwan,China,under Grant Nos. NSC-99-2628-E-002-027,NSC-99-2219-E-002-029the Excellent Research Projects of "National Taiwan University",under Grant No. 99R80300
文摘In multicore environment, multithreading is often used to improve application performance. However, even in many simple applications, the performance might degrade when the number of threads increases. Users usually impute this phenomenon to the overhead of creation or termination of threads. In our observation, how the threads are dispatched to the multiple cores might have a more significant effect. We formally defined the problems on using threads as multithreading anomalies, and presented a novel user dispatching mechanism （UDispatch） which provides controllability in user space to improve application performance. Through modification of application source codes with the UDispatch application programming interface （API）, the application performance can be improved significantly. However, since the application source codes might not be available or it might be too complicated to modify application source codes, we provided an extension, called UDispatch＋, to dispatch threads without any modification of application source codes. In this paper, the UDispatch and UDispatch＋ are integrated and wrapped for more portability and introduced as a tool called Unified UDispatch （UUD） with more detailed experiments and description. It can dispatch the application threads to specific cores at the discretion of users with up to 171.8% performance improvement on a 4-core machine.
基金supported by the Excellent Research Projects of "National Taiwan University" under Grant No. 99R80304
文摘With the growing popularity of 3G-powered devices, there are growing demands on energy-efficient data trans- mission strategies for various embedded systems. Different from the past work in energy-efficient real-time task scheduling, we explore strategies to maximize the amount of data transmitted by a 3G module under a given battery capacity. In particular, we present algorithms under different workload configurations with and without timing constraint considerations. Experiments were then conducted to verify the validity of the strategies and develop insights in energy-efficient data transmission.
