Who has faster multitasking OS/2 or Linux or Windows XP

[gmontem]

For those who have used BeOS and have an understanding of its architecture how does it stack against the other OSes as far as multitasking is concerned?

[Lauwenmark78]

BeOS has a very reactive multitasking architecture - in fact, it was one of its selling points. It used fine-grained threading with a fully preemptive kernel to achieve a high level of responsiveness.

When compared with recent competitors (Linux 2.6.x, Windows NT5, OSX), it doesn't show a perceptible difference, though. That's because the technologies BeOS used are now present in all of them. IMHO, it is still superior to Windows because a given application could hardly lock the whole system (something still easy to achieve today under Windows).

It is pretty hard to determine who has "the faster multitasking" - given the common power of today's CPUs, the context-switching costs are hardly a problem anymore (except for specific cases, like real-time scheduling). The two points that are really relevant today for a desktop environment are:

- How responsive applications are;
- How clever the resources distribution is.

Windows NT5 (The kernel of Windows 2000 and above) multitasking is responsive, but not very clever: an application can get all the CPU, resulting in an overall locked, unusable system. Linux tends to favor intelligent resource management - it is much harder for an application to hog the CPU; on the other hand, it can sometimes be less responsive as NT5, since the "top" application may not get as much CPU time as it would under NT5.

[Kamel]

actually, the "true" answer from a technical standpoint is freebsd/mac comes out on top, then windows, then linux. the reason why windows is slightly faster than linux at multitasking is because linux uses what's called "preemptive multi-tasking". basically what this means is, the linux kernel always maintains 100% control of the program. in a windows os, the kernel gives the processor to a program, then tells it to pass it on until it gets back around. this is slightly faster, but gives the possibility that a single application can take down the entire computer. in linux this is not possible because the kernel never releases the processor to an application exclusively. therefore, in order to crash linux, you would have to crash the kernel itself.

freebsd i am not sure if it uses pre-emptive multitasking or not, but the kernel of freebsd has a very good scheduler, which allows for more efficiant use of the processor than linux and windows, giving you more work for less cpu cycles. (which is why macintosh computers can have a lower mhz rating and still keep up with faster comps). i can't validate that last point about freebsd, but i can definitely say the difference between windows and linux multitasking is if they are preemptive or not.

[Leviathan]

Originally Posted by Kamel

actually, the "true" answer from a technical standpoint is freebsd/mac comes out on top, then windows, then linux. the reason why windows is slightly faster than linux at multitasking is because linux uses what's called "preemptive multi-tasking". basically what this means is, the linux kernel always maintains 100% control of the program. in a windows os, the kernel gives the processor to a program, then tells it to pass it on until it gets back around. this is slightly faster, but gives the possibility that a single application can take down the entire computer. in linux this is not possible because the kernel never releases the processor to an application exclusively. therefore, in order to crash linux, you would have to crash the kernel itself.

This is not true, every Windows with NT kernel has preemptive multi-tasking and even Windows 95 didn't have cooperative multi-tasking as you've described it. The only OSes I know of that actually use cooperative multi-tasking are Oberon and Plurix.
While Linux only is preemptible on the Application side, kernel modules still are not preemptible unless you enable the very experimental and very not working "preemptive kernel" option when compiling the kernel. "Not working" because many drivers still can't be preempted, not because the kernel does something wrong.
Besides, you're messing up the term "crashing" with "freezing".
An application or driver that can't be preempted by the system and doesn't give up the cpu FREEZES the System. On windows (NT) neither apps nor drivers can do that (though they can freeze the GUI which makes Windows useless), on linux apps can't, drivers can.
Crashing means, an app or driver can get the system into a state from which it can't recover and where it can't work properly anymore. This is usually caused by a faulty security system which might enable an application or driver to get write access to OS memory. This does happen in Windows a lot (BSOD and GPF are both symptoms for this kind of error) while similar errors on Linux are unheard of. But this has nothing to do with Multi-Tasking.