With help from a friend, Mark Bellon, I ran a wide variety of tests on several different MacPro configurations. These benchmarks were designed to test the performance of the system on jobs with a large variation in their memory usage. For now, I’m only including plots for the case of double precision floating point operations but I have data for other types, if anyone is interested. As scientists, we are usually concerned with double-precision floating point computations, so I figured that I’d emphasize those results. I’m also including a plot from a Quad G5 for comparison.
Plot 1 is from a 2.66 GHz MacPro with 8GB of RAM. The X-axis represents memory usage on a log scale. The Y-axis is a measure of performance. Note that for a wide variety of jobs, the machine does very well. One can see how the performance of the machine scales well with the number of processor cores. However, for very large memory footprints (several 100 MBs or more) the performance of the machine plummets because the memory subsystem is unable to keep up! Essentially, the machine becomes memory starved the performance suffers. Note that in this regime, although one still gains a lot by having two processor cores, having four, doesn’t help much at all.
Plot 2 is from a 3.0 GHz MacPro with 4 GB of RAM. Essentially, the same observations as in Plot 1 apply. Note that because of the higher GHz, one obtains a higher peak performance.
Plot 3 is from a 2.66 GHz MacPro with 1 GB of RAM. While the essential features of the plot here are the same the ones before, there is one very interesting difference. In this case, even for moderate memory tasks (just over a few 10 MBs) the machine’s performance plummets. In fact, note that in this case having more than even one processor doesn’t help the machine’s performance at all! It appears that to take full advantage of the new memory architecture of the MacPro, one needs to have a good amount of RAM installed. 1 GB is clearly not enough. I’d recommend 4 GB or more.
Finally, I’m attaching a plot from a Quad G5 Security. This is Plot 4. The plot has the same characteristics as the ones above, so I won’t say much about it. Note that the peak performance of the 3.0 GHz MacPro is about 66% percent higher than that of this Quad G5! Thats an awesome improvement.