I've just purchased an old Dell 410 workstation with two 400mhz PII. I know that programs need to be dual cpu "aware" if they are to utilize both cpu's. My question is this: Are linux programs (as they come from Mandrake or RedHat for example) dual cpu aware? and If I compile a program from source on my dual cpu system, will it then be dual cpu aware and utilize both cpu's?

Thanks

Well not all the apps are getting multi-processor awareness, but some I am sure are, I just have no idea which one 'cause I never had a system with more than one processor (I'm a uniprocessor dude ), just make sure you are using SMP kernel.

Thanks for the SMP kernel tip. What if I used Gentoo Linux and compiled everything from source would that make all the apps SMP aware?

It still depends on the app, those that are will and those that are not won't, some may have a configure option and "./configure --help" will help with those ones.

only if the program was made with dual-processor in mind,
and if you happen to own a compiler that knows about
multi-processors .... gcc doesn't.

Cheers,
Tink

P.S.: However, the SMP Kernel will know about the second
CPU and do load-balancing

Thanks guys. We'll see how it goes. This will be a dual cpu all scsi system, that windows will never see.

Don't forget, however, that individual program may or may not be advantaged by having a second CPU. The reason that most stuff is not developed to be SMP aware is because they will not benefit from being able to use both. That does not mean, however, that you will not benefit from being able to use both. As was mentioned above, the SMP kernel is aware and practices load balancing. The only reason that I mention this is because my bro bought a dual 400 system a couple of years ago, and was under the impression that it would run as a uni 800 system... wrong!

Well, My system, as some of you know, is an All Scsi Duel 600mhz p3

And, things like web browsers, word processors, EVEN compiling your kernel, all gets used by the two processors.
I can see that with gkrellm.

Whether it is Gaim, or X-Cdroast, or Xmms, they all run really cool in my duel box.

I can actually top off my 1.8 p4 cpu back home, than I can top off both of these cpu's at the same time.

Plus the super speed of scisi...it''s made my pc able, not to be upgraded at all since I built it in 4 years ago. And it will compete, no problem, with any 1+ gig comp.


Okay, cool....I'm going to get busy now upgrading to kernel 2.4.20

Ok, whether or not GCC knows about smp or not is irrelivent. Basically, any application written with threads can be run across multiple processors (since the threads run indepent of each other). Many programs you use aren't written in a threaded manner because they don't benifit from threads. However, with SMP compiled into the kernel it will run some applications on one processor, and some on the other, so you will still get a performance boost by having the two chips. Theoretically a single threaded application would run no faster on an SMP system, but running multiple single threaded apps would load the system down less on an SMP system then a UP system.

Some people talk about single threaded applications running faster but in reality what is happening is the processor is less busy with other things so it has more time to spend on the particular task.

yep, you are right jtshaw.

smp cpu machines aren't faster than the same cpu speed in a single cpu machine....they simply don't slow down and lag like single cpu machines do.