On Sat, Mar 6, 2010 at 1:51 AM, Rudi Ahlers rudiahlers@gmail.com wrote:
Hi,
I just noticed this article, http://www.howtoforge.net/fully-utilizing-your-x-core-cpu%C2%A0which uses http://code.google.com/p/ppss/%C2%A0for parralel processing.
So, can anyone tell me if parralel processing happens automatically on CentOS, or would I need to use this script as well? We mainly have Dual Core & Dual CPU, Dual Core (i.e. 8 cores) servers and it would be benefitial to know whether any applications on the server could automatically use all 8 cores, or whether I need todo something on the servers to get this working?
I haven't read the articles, but in general the answer is yes and no.
Linux is a multiprocessor capable OS that will automatically use as many processors as are available and needed to run whatever is in the running process mix.
However, if your application is single-threaded, it can't be multi-processed because the OS has no way of knowing how that should be done.
In order to be run in parallel (note spelling, pls), an application has to be written to run multiple threads of control be they Linux threads, multiple processes or whatever. Most modern OSs are inherently capable of parallel operation because they will use as many processes and threads as they need to run the hardware and support system and user processes that are enabled to do the same.
So, if you want an application to run in parallel, it must be written to be parallel capable - multiple threads that operate at least partially independently with appropriate controls to synchronize critical resources without livelocks or deadlocks. I don't know the internal structure of apps I haven't written or worked on, but I'm pretty sure OOO and probably a fair number of the graphical and multimedia apps are multiprocessor capable.
The big advantage to having multiple CPUs is being able to run multiple processes simultaneously, whether that's one multithreaded app or <#-of-CPUs> different apps, multithreaded or not.
There are other performance issues that also need to be taken into account, but that can get fairly complex and is not necessarily on point.
Mark Hull-Richter Expert Software Developer Registered Linux User #472807 - sign up at http://counter.li.org/