Scott Ford asked:
> what are Assembler no nos in performance ...
Here are some examples (from my session 12522 talk at SHARE in San
Francisco):
1. Memory speed is very slow compared to CPU speed -- for example, use
immediate operands wherever possible
2. Operand alignment can be very important (doubleword alignment if
possible!)
3. Don't mix instructions and data -- keep them far apart
4. Modifying instructions "on the fly" is "performance poison"
5. Minimize Address Generation Interlock (you can put other unrelated
instructions between these two at little or no cost because the CPU has to
wait until the first Load completes before it can execute the second)
L 1,Pointer
L 2,0(,1)
6. Arrange branches so the "fall through" path is most frequent
7. Keep data references close in memory and time
8. Keep instruction references close in memory and time
That's a start, anyway.
John Ehrman
