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Posted: Sat Nov 11, 2000 12:01 am Post subject:

greetings! Would someone be kind enough as to explain (in layman's terms) how dual processors work? does the entire computer run faster? I am thinking about going dual processor when i upgrade my computer...are there any disadvantages? Thanks for your time!!

Posted: Sat Nov 11, 2000 5:04 am Post subject:

Dual processors, hmmm...Well lets start with the only disadvantages I know of, Win9x can only see and use one and 2 CPUs is more expensive than 1. Now if you plan on running an OS that can utilize 2 CPUs yes the system is a hell of alot faster. An OS that is multi-processor capable will split it's processing needs between the 2 CPUs giving you twice the speed for the OS. Some programs are not written to specifically use 2 CPUs but many times the OS can handle dumping the process of to a different CPU or balance the CPU usage even if the programs you run can't by themselves. The sheer power of running 2 CPUs is evident almost immediately. I can open up some very intense programs that would normally slow my entire system down but with 2 CPUs I hardly notice. Also something that helps greatly is a boat load of memory. Whether its WindowsNT/2K or Linux or BeOS lots of memory is always appreciated unlike Win9x where the difference between 128MB and 256MB is almost nothing. I know I haven't explained exactly how dual processors work so let me try. When a program executes it creates at least 1 thread(a conduit in the processor). The thread(32-bit apps have multiple threads) are given a number to represent their importance. Higher the importance the more CPU cycles a thread is given. Down this thread the app sends code to be execute or processed and if an app has more than one thread and the PC has more than one CPU then the OS can split the threads up among the CPUs. Executing two parts of the app on separate CPUs instead of having to wait for the first part to be executed on 1 CPU and then execute the 2nd part you can execute both simultaneously. Obviously this cuts the time it takes to execute by half, give or take a few. ONe of the drawbacks of Intel's implementation of dual CPUs is that both processors share the same pipe to the memory and card bus which means a slow down especially to memory intensive apps. That is why SETI is not twice as fast on a 2 CPU system, unless of course your CPU has enough L2 cache that SETI doesn't have to use main memory. Unfortunately only the Xeon processor has enough cache, but hey thats life.

Rover
"...She went to the cupboard to get her poor dog a bone,
when she bent over Rover took over and gave her a bone of her own!"

Posted: Sat Nov 11, 2000 1:40 pm Post subject:

wow! that sounds cool, I think I shall stay away from intel for now when i can purchase 2 AMD's for the price of 1 Intel chip! Another question: does the booting speed up also? so...let me get this straight, dual cpu's split up the program so that half runs on one and half runs on the other at the same time, speeding up the proccessing entirely? How is it that some programs cannot utilize dual cpus? This is cool stuffs! Thanks for you help dude!

Posted: Sat Nov 11, 2000 2:19 pm Post subject:

Well I'm not a programmer so I can't give you the exact nature of how a program is optimized for duals but they definitely are out there. For instance Adobe Photoshop, I'm told it can utilize both processors for itself, giving extremely fast rendering speeds! LightWave is another also a graphic 3D animation package can not only use more than one CPU but has distributed processing capability! Let it be noted that the OS(in this case Win2K) handles any hardware usage. Anyways most of your average proggies if they can't be split over 2 CPUs will get CPU 1 and the OS will move itself over to the other CPU(s). 32-bit apps with their multi-threading capability are perfect for a dual(or better) computing environment. MS Office2000, IE, Outlook Express, PhotoShop, etc. 16-bit apps I'm not sure about but I think they get one thread for all 16-bit apps running, which is why in the old days when an app crashed the whole system went down because the thread could not be removed! As far as booting is concerned I'm not real sure since I've been using dualies for so long I don't know what its like to boot Win2K on a single Celeron 433Mhz CPU. I hope what I've said is accurate, it might not be but I think it is close! Remember to wait for the new AMD chipset the 760MP or something since it will provide the first Athlon/Thunderbird/Duron multi-CPU capability.

Rover
"...She went to the cupboard to get her poor dog a bone,
when she bent over Rover took over and gave her a bone of her own!"

Big Dog Joined: 20 Oct 2000 Posts: 3689 Location: USA

Quote:

Another question: does the booting speed up also?

that depends on the OS, but for win2k the answer is NO

win2k loads a larger kernel for SMP support, and it takes longer to load the extra code, most of which is sent to the first CPU for the majority of the boot process. so win2k is actually slower to boot on DP (dual processor) systems then it is on single processor machines. That applies up to just before you get the "logon" after that it screams with dual cpu's, but since by that point most of the code has already been loaded, it doesn't quite catch up to the load time of a single CPU system

of course the couple of seconds lost on boot time are easily made up for by the DP system for actual applications/processes

There is NO spoon !
-Brain