Abstract
Loop unrolling is the main compiler technique that allows reconfigurable architectures achieve large degrees of parallelism. However, loop unrolling increases the area and can potentially have a negative impact on clock cycle time. In most embedded applications, the critical parameter is the throughput. Loop unrolling can therefore have contradictory effects on the throughput. As a consequence there exists, in general, a degree of unrolling that maximizes the throughput per unit area.
This paper studies the effect of loop unrolling on the area, clock speed and throughput within the ROCCC, C to VHDL compilation framework. Our results indicate that due to the unique design of the ROCCC compilation framework, FPGA area either shrinks or increases at a very low rate for the first few times the loops are unrolled. This reduced area causes the clock cycle time to decrease and thus a great gain in throughput. Our results also show that there are different optimal unrolling factors for different programs.
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Buyukkurt, B., Guo, Z., Najjar, W.A. (2006). Impact of Loop Unrolling on Area, Throughput and Clock Frequency in ROCCC: C to VHDL Compiler for FPGAs. In: Bertels, K., Cardoso, J.M.P., Vassiliadis, S. (eds) Reconfigurable Computing: Architectures and Applications. ARC 2006. Lecture Notes in Computer Science, vol 3985. Springer, Berlin, Heidelberg. https://doi.org/10.1007/11802839_48
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DOI: https://doi.org/10.1007/11802839_48
Publisher Name: Springer, Berlin, Heidelberg
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