This too is erroneous information:
"Lets say you have two programs, neither of which are multi-threaded. If you have a dual processor system, will windows send the workload of both of them to the same processor or is it smart enough to send them to separate processors?
Ahhh, No.
Windows will not send different programs to different CPUs."
Completely erroneous, and easy to demonstrate with Task Manager (Performance tab) and two compute-bound applications on a dual-CPU machine.
If you have two CPUs, the two highest-priority ready threads are going to run simultaneously - whether they are in the same application or different applications.
This is vastly simplified. For example, there is a mechanism to make sure that all ready threads get SOME CPU time, regardless of their priority - this prevents a high-priority thread from completely hogging the CPU. And, processes (applications) can specify that all of their threads must be run on a single CPU (this is rare - done only for some older programs that were not written with proper locking code), and processes and threads may specify WHICH CPU(s) they may run on.
Again, nearly all applications today are multi-threaded and designed to run on multiple CPUs. The "Photoshop is the only application that benefits from multiple CPUs" argument is YEARS out of date.
That said, there is an inefficency associated with using multiple CPUs. Two 1 gHz CPUs are not going to be as fast as 1 2gHz CPU. On the other hand, multiple CPUs makes Windows operation much more "fluid". And, once you max-out on clock speed, there IS only one way to get faster - add more CPUs.
When I move from my dual-CPU desktop machine to my notebook, the difference is startling. I would never want to live with a single-CPU machine as my primary computer. Intel has come to the rescue, though - the lastest notebook Pentium IV's have Hyperthreading technology, and single chips with true dual-CPU cores are also on the way. Within 5 years, there will not be any single-CPU systems produced. |
