Why is a slower MIP rate with new z10 instructions better?

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Why is a slower MIP rate with new z10 instructions better? The answer based on the initial results of problem #18 solution posted today on the ZMFACC Mainframe Assembler Coding Contest would appear to be that by using the new compare and branch instruction for z10 replacing 2 separate compare and branch on condition instructions results in a lower MIP rate but a faster execution time. Even though the MIP rate is lower, there are fewer instructions required to do the same work, and the elapsed time required is less. For the solution posted, the MIP rate using z390 on Intel Duo Core 2.1 GHZ processor dropped from 8.7 to 7.3 MIPS or 15%but the elapsed time also dropped from 343 ms to 271 ms or an 8% reduction in elapsed time. To see the source code and execution log output for this solution plus new problem #19 posting visit:

http://z390.sourceforge.net/z390_Mainframe_Assemble_Coding_Contest.htm

Don Higgins
don@higgins.net