Buffer-based Scheme Research Articles

Fault buffers

Voltage scaling can be applied to cache memories to reduce their energy consumptions. However, reduced supply voltage to the cache memories increases the number of defective SRAM cells due to process variations, which will decrease their yields and nullify the benefits of voltage scaling. To mitigate this problem, we propose a fault buffer-based scheme for L1 caches. Faults are identified and isolated at the granularity of individual words in the L1 caches. Actively used faulty cache words are dynamically allocated in the fault buffers. The fault buffers are organized as multiple banks for low cost implementation and can be dynamically reconfigured to reflect varying performance demands of programs. This dynamic scheme is shown to be more energy- and area-efficient than, and to be performing comparably to, the previously proposed static schemes.

Partial rollback in object-oriented/object-relational database management systems with dual buffer

Partial rollback mechanism has been widely supported by many database management systems (DBMSs). It allows a transaction to be rolled back partially, that is, only back to a certain savepoint set by the user. A partial rollback, however, makes the DBMS buffer management complicated because it requires the DBMS to restore the state of not only the database but also the buffers. There are several literatures addressing such a partial rollback in a relational DBMS (RDBMS), which has page buffer only. However, to our knowledge, there exists no literature addressing it in an object-oriented/relational DBMS (OO/ORDBMS). The RDBMS partial rollback scheme cannot be applied to OO/ORDBMSs directly. The reason is that, unlike RDBMSs, many OO/ORDBMSs use dual buffer which consists of object buffer and page buffer. In this paper, we thoroughly study the partial rollback schemes for OO/ORDBMSs with dual buffer. For this, we propose four different partial rollback schemes which are based on (single) page buffer, (single) object buffer, dual buffer using a soft log, and dual buffer using shadows, respectively. The schemes proposed are practical enough to be implemented in a real OO/ORDBMS. The results of performance evaluations show that the dual buffer-based scheme using shadows achieves the best performance.