How to take advantage of Dual Core?

[Dexmaus]

is there a program that automatically signs affinity for you for different programs that u are running? or this is done by windows XP itself? how to take full advantage of dual core?

 

[Unkno]

don't need to worry about it. windows will handle the processes to different programs. Note that windows would only take advantage of your second core when a process is multithreaded or your running more than one process/program

 

[Munky]

Windows handles it automatically, and it uses both cores. If I run one demanding process, it will not run 100% on one core, but instead it will use both cores more or less 50%. If you want to run the process on one core only, then you have to manually set the affinity. To use both cores at 100% a process needs to be coded to use multiple processors when available.

 

[perdomot]

Is there a way to tell if a program will benefit from dual core cpus? I'd like to know which programs I run gain from my dualie.

 

[soydios]

Some misconceptions in the above few replies:

- @Unkno
You are always running more than one process. Hit Ctrl-Alt-Del in Windows, and look at the bottom left of the Windows Task Manager window. It shows you how many processes are running. Dual core is best used in a multitasking environment (multiple programs and/or windows open at once). Because there are two cores, programs have to wait in line for less time to use the CPU. The analogy is like airport check-in: one person behind the desk can only handle one task at any given time, but two people let's you handle two tasks, and theoretically twice as many people. I say theoretically because dual-core CPUs still have to share the same memory and hard drive buses.

- @munky
One process will run on one core. It will not run simultaneously on two cores. So, one process (a videogame, for instance) will use one core 100%. This is why dual-core CPUs currently offer very little, if any, performance boost to games, as there are just about no multi-threaded (one game spawns multiple processes) games out there. Expect multi-threaded games to come soon (they are already arriving for XBox360 and are in development for PS3). But, if you have a second core, then you can run two processes at (or, because of shared resources, near) 100% (like a game and video encoding).

Some answers:
- @Dexmaus
Windows XP automatically schedules processes for the CPU. It will automatically take full advantage of a dual-core system.

- @perdomot
You can always benchmark the programs. Run them without changing any settings to determine dual-core performance. Then, open Windows Task Manager (Ctrl-Alt-Delete), right click the process that you are looking for (often an odd but recognizeable abbreviation of the program name .exe), right click it, and set its Affinity to either CPU0 or CPU1. Benchmark the program again to get single-core results. If the dual-core results are better than single-core, you have yourself a winner.

 

[perdomot]

Thanks for the idea!

 

[pcoffman]

Originally posted by: perdomot
Is there a way to tell if a program will benefit from dual core cpus?

Any program that is multi-threaded. As to how to know if the program is multi-threaded, I don't know, other than reading, or benchmarking, as soydios suggests.

 

[pcoffman]

Originally posted by: soydios
open Windows Task Manager (Ctrl-Alt-Delete), right click the process that you are looking for ... right click it, and set its Affinity to either CPU0 or CPU1

This advice is worth its weight in gold. I can now set an encoding program that used to hog 100% my CPU resources to just use one of my simulated hyperthreaded cores. Now I can get work done, while I encode. I can actually use my computer! Thanks, soydios.

 

[Munky]

Originally posted by: soydios

One process will run on one core. It will not run simultaneously on two cores. So, one process (a videogame, for instance) will use one core 100%. This is why dual-core CPUs currently offer very little, if any, performance boost to games, as there are just about no multi-threaded (one game spawns multiple processes) games out there. Expect multi-threaded games to come soon (they are already arriving for XBox360 and are in development for PS3). But, if you have a second core, then you can run two processes at (or, because of shared resources, near) 100% (like a game and video encoding).

So how is it that when I run an app like rthdribl, it loads my dual core cpu at 50%, but in task manager it shows core1 being loaded about 75%, and core2 loaded about 25%. If I set affinity to either core, then it loads that core to about 90-95%. To me that looks like at least for a fraction of the time rthdribl runs on the second core, even though it uses the first one mostly. Of course, it doesnt actually run on 2 cores at the exact same time, but it does seem to run on both at various intervals.

 

[dmens]

Yes, when the OS switches the thread out, then back in, it just picks a core at random, unless forced to pick a specific core. The load averaging comes out to half. But obviously a thread can only use one core at a time.