Linux MultiThreading ???? Realy ????

ak_47_boy · 01-12-2006, 12:12 PM

Is it true linux will enable a program that is not multithreded to use multiple prosessors?

angustia · 01-12-2006, 01:11 PM

a program that has only one thread will be executed by one processor at time, but not tied to a specific one...

jtshaw · 01-12-2006, 01:43 PM

As angustia said, it could use multiple processors at different times, but never at the same time. What typically happens is your process gets context switched out of execution (because it is waiting on a "long" system call or it ran out of quanta) and when it gets selected for execution again it happens to be on a different physical CPU.

The kernel makes no attempt to introduce parallelism to a non parallel process. This would be quite difficult to accomplish.

ak_47_boy · 01-12-2006, 02:45 PM

So the program wont run any faster with 4 prosessors than it would with 1 ?

pixellany · 01-12-2006, 03:08 PM

An individual application will not benefit from multiple processors unless it was designed to.

On the other hand, a computer system running many process and applications, can definitely benefit. How much depends on the combination of thing running. One thing I do frequently is create a big print queue which chugs away for over an hour while I go surfing. I am sure that this scenario would be more responsive with dual processors.

ak_47_boy · 01-12-2006, 03:48 PM

Is there any programs out there ether for windows or linux that will enable a single threaded program to take advantantage of a multiprosessor machien? Emulation? Virtual Prosessor?

jtshaw · 01-12-2006, 05:02 PM

Quote:

Originally Posted by ak_47_boy

Is there any programs out there ether for windows or linux that will enable a single threaded program to take advantantage of a multiprosessor machien? Emulation? Virtual Prosessor?

No, it would be extremely difficult to take a single threaded program and automatically make it into something that would benefit from parallel processing. It would take a ridiculous amount of source code analyzing before the program was run to made any significant increase in speed.

However, the more CPU's you have the better a chance your program will get execution time.

Hammett · 01-12-2006, 06:59 PM

IMHO we will have to wait until programmers code thinking in multi-processor machines. Until then, we won't take that much advantatge of multi-cored CPUs.

jtshaw · 01-12-2006, 07:16 PM

One non-threaded application might not see a performance increase, but multi-core systems can run threaded processes faster (things like oracle, apache, parallel compiles, ect.) and can run two single threaded processors at the same time. There absolutely is an overall increase in system performance with multiple cores.