Case Study #3
Notes:
Applying the calculations from the previous slide, 24 full-duplex channels would require eight 100 MIPS C54x’s. The total C54x processor cost would be $264, $11 per channel, and only 38.3 mW / channel. For the C6x, we assumed a 4X improvement in performance vs. C54x. This number was not 5:1 ratio vs. C54x in this case because we want to present the realistic idea that while theoretically the number of channels will fit onto a C6x from a performance standpoint, there is some question of whether the memory requirements of more than 12 channels per DSP can be met. This is meant as a exercise to show that there are 3 factors that must be considered with respect to # of channels: 1) what is maximum # of channels that will “fit” on the DSP from a performance standpoint; 2) what is the maximum number of channels that can be handled from a memory standpoint; 3) what is the maximum number of channels that can be handled taking I/O limitations into consideration. In this case, considering 12 channels, the DSP processor cost / channel of the C6x is significantly better than the C54x ($8 / channel vs. $11 / channel). However, the C54x has a much better power / channel number. Once again, the consideration must be made as to whether channel density is number 1 issue or a combination of factors.