Today we took a rapid-paced tour through the realm of vector processors, including SIMD, SPMD, manycore, and GPU systems, dwelling a bit more on the progression of GPUS, since they have proven to be a viable product (unlike most of the others). As we saw, GPUs have been growing rapidly in performance via four main techniques. (1) shrinking feature sizes on the chips, (2) making the chips bigger, (3) extending the ISA with new features and additional functional units, and (4) specializing the architecture into multiple models, with modest variations that tune the performance for particular markets (e.g., 64-bit FP support for scientific processing, versus 16-bit FP support for AI). Clearly, however, as the GPU is reaching the point where the chip is more than a square inch in area, dissipating 300W of heat, and VLSI feature size reductions are slowing down as we approach the limits of CMOS scaling, emphasis is shifting to the latter two. We also saw that the use of multi-chip modules is still a difficult technology to implement, suitable mainly for markets that tolerate higher cost. 

We can thus expect that, in the future, we will see much greater emphasis on increasing performance through specialization of architectures — tuning the hardware to the characteristics of the appication domain. The same will be true in all areas of architecture, not just vector systems. 

Looking ahead to our remaining classes, the draft of the final project report will be due on Monday so that I can return it with comments in time to take questions on Wednesday. Monday will also involve additional in-class work. 

Our last class will be another round of demos. As noted previously, there is no final exam, and the in-class exercises we’ve been doing since Spring Break will take the place of that in the grading. 

The final exam is scheduled from 8 to 10 on May 7, and I will have the zoom meeting running during that time so that teams can show any follow-up demos they would like to do (e.g., if additional work is done, or bugs are fixed from the demo next Wednesday). Don’t wait until the last 30 minutes of the exam period to sign on, however, because we won’t be able to fit everyone into that amount of time. The final version of the project report is also due that day. 

Slides are here