[nycdunz]

i heard most games only use single processor. if you have a dual processor machine, you need to activate it via terminal. Is this true? If so, how does one do this? i heard this works for games like doom 3, call of duty, etc..

[Buck_Naked]

The game/ applications needs to be coded for dual processors.

[Kristoff]

That's not quite true either.

For the most part, OS X thread scheduler does a good job splitting the load on it's own, assuming the game is reasonably multi-threaded.

[Leonard]

Originally Posted by Kristoff

assuming the game is reasonably multi-threaded.

That's what he meant by the app must be coded for it!

Very few games are coded for multi-processors. As far as I'm aware, only Quake 3, Jedi Knight 2, and possibly RTCW is dual processor aware. UT2003 and UT2004 had the ability to offload the sound onto the second processor, but it really didn't help much. As far as I know Doom 3 is not dual processor aware.

The good news is that future games like UT2007 will be made for dual processors and dual core chips, largely because the Intel world has hit the Mhz wall and is realizing, finally, that dual cores is the way to go.

[Kristoff]

No, you missed what I said.

Most current games are indeed multithreaded. Multithreaded programming has nothing to do with processor count per se, but the Mach scheduler does a good job of load balancing threads.

[Leonard]

While yourright that the OS X scheduler does a great job of balancing processor load, most games are not multi-threaded and therefore about all the scheduler can do is put the game on one processor and balance the rest of the OS threads around it. What needs to happen and is happening slowly, is to get games multi-threaded.

Running Quake 3 with SMP on and off shows off the difference quite dramatically (if I remember correctly), as putting SMP on will almost double framerates.

[Kristoff]

When I run RTCW ET, it spawns 6 threads and the CPU load is spread across 2 cpus.

[Horsepoo!!!]

There's an on/off switch for the second processor at the back of the computer.

[Scotttheking]

Originally Posted by Kristoff

When I run RTCW ET, it spawns 6 threads and the CPU load is spread across 2 cpus.

Originally Posted by Leonard

That's what he meant by the app must be coded for it!

Very few games are coded for multi-processors. As far as I'm aware, only Quake 3, Jedi Knight 2, and possibly RTCW is dual processor aware.

mmm

[Brad Oliver]

Originally Posted by Kristoff

When I run RTCW ET, it spawns 6 threads and the CPU load is spread across 2 cpus.

5 of those threads originate from the OS, and have such a low load that they're negligible for most cases. You're not going to see it eating up 200% CPU time (the max for a 2 CPU system), that's for sure.

[Brad Oliver]

Originally Posted by Kristoff

Most current games are indeed multithreaded.

Technically, this isn't true. Most current games are single-threaded. They may spawn off a few more threads as you noted in your other post, but these are really coming from within the OS and the services it provides, and they don't really help performance in a measurable fashion.

[jman]

Originally Posted by Horsepoo!!!

There's an on/off switch for the second processor at the back of the computer.

Does my powerbook have this switch?



j/k

[Leonard]

Thanks for your replies, Brad. I should have remembered that the other threads are OS threads.