processors)]: Parallel processors General Terms

In Transactional Memory (TM), a conflict occurs when a memory block is accessed concurrently by two or more trans-actions and at least one of them is a write access. The man-agement of conflicts significantly impacts TM performance. There are two alternative approaches for managing conflicts: Reactive Contention Management (RCM) [1] and Proactive Contention Management (PCM) [2]. Previous contention management schemes treat all transactions with no weights, and make a decision based on the information provided by the running transaction instance. In this work, we suggest that all critical sections (trans-actions) are not equally performance-critical. Among the transactions from a program, some transactions are more important than others with respect to the performance of the implemented algorithm; e.g., the producer transaction in the producer-consumer relationship. It is worthy to dis-tinguish the performance-critical transactions from others for speeding up the overall execution. For this purpose, we propose a mileage technique and show its effectiveness in the contexts of RCM and PCM. To express the criticality of transactions, we define new in-structions, MILEAGE and MRSTCNT. MILEAGE has one oper-and, mileage id (mid). A mid indicates how far a thread pro-gresses and monotonically increases during the program ex-ecution. Each processor has a mileage unit. A mileage unit maintains the current mid and a mileage counter (mcnt), which tracks the number of times that MILEAGE has been ex-ecuted with the current mid as its operand. When MILEAGE with a new mid is shown, that mid is stored in the mid register and the mcnt register is cleared. Every time the same mid appears again, the mcnt register is incremented. Copyright is held by the author/owner(s)