Mahesh Sukumar Subramanian Srinivasan

Introduction Embedded system products keep arriving in the market. There is a continuous growing demand for more functional and more complex appliances. Great challenge to design the embedded system applications.  These systems must have enough processing power to handle these tasks.

Java Java is becoming increasingly popular in embedded environments. More then 721 million devices are shipped with Java each year. Furthermore, it is predicted that 80% of mobile phones support Java.

Current Design goal Current design goals must include a careful look on embedded Java architectures. Embedded systems must have  Low power dissipation.  Support a huge software library to cope with stringent design times. Need for architectures that can support all the software development effort currently required.

Java compliant Architecture Binary Translation Unit. Reconfiguration Cache. Reconfigurable Array. Speeds up the system and reduce energy consumption. Results in extra area.

Binary Translation Unit A separate unit is responsible for  dynamic analysis of the instructions.  find the sequences that can be executed in the array. BT saves the configuration for the potential sequence of instructions in a reconfiguration cache. There is a delay involved with the reconfiguration. If the sequence of instructions is going to be repeated performance and energy gains are meaningful.

Reconfigurable Cache List A write command for the reconfigurable cache is sent. This command saves the content of the buffer to this cache. This list is made in real time, as the instructions are fetched from memory. The size of the buffer is of 20 eight-bit registers long.

Reconfigurable Array The used coarse grained reconfigurable array is tightly coupled to the processor. The array is divided in blocks, called cells. The operand block (a sequence of Java bytecodes) previously detected is fitted in one ore more of these cells in the array.

Cell of the Reconfigurable Array The initial part of the cell is composed by three functional units (ALU, shifter, ld/st). After the first part, six identical parts follow in sequence. Each cell of the array has just one multiplier and takes exactly one processor cycle to complete execution. For each cell in the array, 327 reconfiguration bits are needed. Consequently, if the array is formed by 3 cells, 971 bits in the reconfiguration cache are necessary.

Run time detection and analysis The detection is performed at run time. The next time that the sequence of instructions is detected it can be executed in the array. Prevents loss of cycles for execution.

Results The tool utilized to provide data on the energy consumption, memory usage and performance is a configurable compiled-code cycle accurate simulator. We compare the processor coupled with the reconfigurable array with VLIW versions with the same instruction set.

Conclusion We showed in this paper the implementation of Java compliant architecture to work with a coarse-grain array in a native Java processor. Boosts performance and reduce energy consumption. The search of the potential sequence of instructions is done at run-time. Furthermore, we demonstrated that there is no need for huge available parallelism in the application, such as it is in VLIW and Low power architectures, to achieve good results.

Future Work More algorithms concerning the optimizations aimed at the reconfigurable arrays can be evaluated. Furthermore, we can use another Java processor for the analysis of instructions instead of a dedicated hardware.

Thank you.