>>Alas, it looked good on paper, but died in practice, either because the theory was flawed (but academic simulations seemed to suggest it would be a win), or because Sun didn't have the resources to invest in it properly and Oracle killed it.
I heard this never actually worked at all and they added the ability to turn off the hardware scout entirely before canceling it. I'm not really sure how the scout was supposed to be able to help performance. If the algorithm is indirect heavy then speculatively running it won't help you. On the other hand, if it isn't you might as well rely on conventional prefetch. Do you have a link to those studies?
>> If it turns out you have to actually restructure your code to get this 2.3x performance, rather than gcc-recompile with a different architecture, then it's not really an apples-to-apples speedup.
Right, I would only add that the algorithm itself has to be amenable to that architecture in the first place. Most general purpose code isn't and won't be able to take advantage of a large number of parallel execution resources.
I heard this never actually worked at all and they added the ability to turn off the hardware scout entirely before canceling it. I'm not really sure how the scout was supposed to be able to help performance. If the algorithm is indirect heavy then speculatively running it won't help you. On the other hand, if it isn't you might as well rely on conventional prefetch. Do you have a link to those studies?
>> If it turns out you have to actually restructure your code to get this 2.3x performance, rather than gcc-recompile with a different architecture, then it's not really an apples-to-apples speedup.
Right, I would only add that the algorithm itself has to be amenable to that architecture in the first place. Most general purpose code isn't and won't be able to take advantage of a large number of parallel execution resources.