MDX on 07 June 2008
Sure no problem:
Here is the question I posed, based on my readings and the response by well respected "techie" on the forum:
So how important is the fact that the Wii's CPU can process Out-of-order vs the Xenon and Cell both (as I understand) are forced to process In-order?
In-order processors, based on earlier processors
New paradigm:
The key concept of OoO processing is to allow the processor to avoid a class of stalls that occur when the data needed to perform an operation are unavailable.
The benefit of OoO processing grows as the instruction pipeline deepens and the speed difference between main memory (or cache memory) and the processor widens. On modern machines, the processor runs many times faster than the memory, so during the time an in-order processor spends waiting for data to arrive, it could have processed a large number of instructions.
In-order processors, based on earlier processors
New paradigm:
The key concept of OoO processing is to allow the processor to avoid a class of stalls that occur when the data needed to perform an operation are unavailable.
The benefit of OoO processing grows as the instruction pipeline deepens and the speed difference between main memory (or cache memory) and the processor widens. On modern machines, the processor runs many times faster than the memory, so during the time an in-order processor spends waiting for data to arrive, it could have processed a large number of instructions.
If the CPU's are Designed Properly it shouldn't be an Issue... It's Simply a Design Choice like Big Endian and Little Endian coding... However many groups have spoken out saying that the X360 and PS3 have Branch Prediction Issues and SlowDown that could be Caused by the use of In Order Processing... In Order created too many WaitStates where the CPU is waiting on Ram to free up... This could be corrected by Higher Speed Ram or Matching the CPU and Ram Speeds while using Several Cores... Overall it's possible that the x360 spends about 10% of it's time waiting and not processing anything same can be said for the PS3... This is where the Wii with Out of Order Processing and Hi Speed Ram is a Nice thing... You never need worry if the System is ready to handle your Request...
Let's face it CPU Clock Speeds have pretty much hit a wall... So Out of Order is the way to go in any High End System at this point... The Divide between CPU and Ram Clock Speeds will only get worse in the coming Years... This has been noticeable since Prior to the advent of the Original Pentium...
