Worst-Case Execution of One Instruction
Consider
ld r0,r7,12
—an assembly language instruction that means load register r0 from the memory 12 bytes off the address in register r7. To give us a starting point, let's say that the processor is rated at 100 MIPS. We would expect this instruction to take about a hundredth of a microsecond, or 10 nanoseconds.
Most of the time the instruction will take about 10 nanoseconds, but if everything conspires to hurt the performance of this single instruction, it could take as much as 100 milliseconds to get to the next instruction. That represents a performance difference of about a factor of ten million between the most likely execution time for the instruction and the longest time it could take.
Worst-Case ...
Get Real-Time Java™ Platform Programming now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
