mark@hubcap.clemson.edu (Mark Smotherman) (04/27/91)
djbailey@skyler.mavd.honeywell.com writes: > Suppose we describe a computer's performance as an n-dimensional > vector. What would the dimensions be? You might want to look at how Dan Siewiorek used Kiviat graphs rather than vectors, i.e., pp. 46-48 in D.P. Siewiorek, C.G. Bell, and A. Newell, Computer Structures: Principles and Examples, McGraw-Hill, 1982. These graphs are visual representations of performance measures for, in Siewiorek's case, CPU processing (memory accesses/sec), main and secondary memory capacities and speeds, and three communication speeds (communication, external, human). The advantages that he sees for Kiviat graphs include a summary of major performance parameters and a graphical representation of system balance. Certainly the CPU performance metric is up for grabs. You can reject the usual suspects (e.g., MIPS, MOPS, MFLOPS). The reciprocal of CPI might be somewhat better but has obvious disadvantages in dealing with instructions like fused-multiply-add and HP's branch-and-add. Something like SPECmarks looks the best to me. Siewiorek also recently stated that for balanced contemporary systems Case's ratio (1 Mbyte of memory per CPU MIPS) and Amdahl's ratio (1 Mbit of I/O bandwidth per CPU MIPS) should both be upward adjusted by a factor of 8. These ratios probably shouldn't be expressed in terms of SPECmarks since SPEC, as of yet, only stresses the CPU and cache. However, looking at a scatter(!!) plot of SPECmarks vs. (1st+2nd)-level cache sizes, how about this ratio for a balanced machine: 6.4 Kbytes of cache per SPECmark: 5 SPECmarks ~ 32 Kbytes 10 SPECmarks ~ 64 Kbytes 20 SPECmarks ~ 128 Kbytes 40 SPECmarks ~ 256 Kbytes -- Mark Smotherman, CS Dept., Clemson University, Clemson, SC 29634-1906 mark@cs.clemson.edu or mark@hubcap.clemson.edu