About multitasking, what's best : AmigaOS, Linux, or Winblows XP ?

[ptek]

Hello,

Multitasking seems to be a hot matter these days.

For who use a lot Linux and Winblows (XP, 2000, NT) could please tell us what OS does best multitasking and why. Amiga still does it better than the others ?

And I was forgetting MacOS ...

Please justify your claims

[Tomas]

AmigaOS.. I am no expert on the multitasking in windows and linux, but it does seem to give a smoother experience when multitasking under amigaos.
BeOS multitasking also seemed to work in a similar way to AmigaOS.

[ptek]

So, the Amiga is better at multitasking than Linux ?

[Tomas]

ptek wrote:
So, the Amiga is better at multitasking than Linux ?

From how it feels to me, then yes. But i can only talk from a user perspective.

[Zac67]

IMHO AmigaOS performs better than Windows XP & Linux because it features a more modern microkernel.
Windows NT/2k/XP/2k3 started out as a micro kernel, but was evolved into a hybrid.
OS X shares the same fate, but to a much lesser degree.
Nearly all Un*x flavors use a monolithic kernel that actually caused Linux to scale very badly when it came to SMP some years ago.

[itix]

For who use a lot Linux and Winblows (XP, 2000, NT) could please tell us what OS does best multitasking and why. Amiga still does it better than the others ?

Linux and XP or NT. Windows 95 already equals with AmigaOS.

In AmigaOS multitasking stops when high priority process decides to busy loop. In Linux and Windows you can kill process at will.

MacOS and Windows 3.x dont have multitasking at all. They only pretend so.

[stopthegop]

In Linux and Windows you can kill process at will

haha!  Welcome to Fantasy Island.  That works like maybetwo times out of ten.   Its almost always a reboot.  If I had a dime for every time I've had to reboot windoze I could retire rich, about 10 times over.  

[SamuraiCrow]

@OP
AmigaOS multitasks better becuase it uses a flat memory model.  XP and Linux have to switch MMU registers for the localized memory maps of each app.  MacOSX uses a microkernal but still requires the localized memory map for each application so it's still slower than the equivalent Amiga (if such a machine exists).

@Itix
Oh and incidently Windows 9x didn't multitask either.  It just ran background processes while waiting for mouse clicks and keystrokes.  While the foreground task was running, it hogged the processor.  At least the AmigaOS multitasks preemptively for equal task priorities.

You're right about a busy-loop in a higher-priority process though.  

[Piru]

1. Linux

New 2.6 kernels have nice nice O(1) scheduler and kernel pre-emption.

2. Mac OS X

BSD scheduler basically, tried and tested solution.

3. Windows

I have no firm details how windows scheduler works, but I believe it's BSD variant, or at least acts very close to it. Whether other parts of the OS are very efficient is separate issue (for example Windows memory paging is quite horrible, well... memory is ultracheap these days :-)). In general, Windows scheduler works fine.

4. AmigaOS

Very limited and aged round robin scheduler. Only pre-Windows 95 and classic Mac OS are worse. Tasks running at higher pririty hog all CPU time from lower pri tasks. Task running at same priority don't have fair CPU time sharing. Executive helps a bit by giving BSDish features. AmigaOS and typical applications are very light, which makes the system very responsive. On the other hand there is single global memory map, no resource tracking, memory protection or swap, making the system faster but more vulnerable and prone to crashes.

PS. I am talking about technical merits and qualities here.

[Speelgoedmannetje]

SamuraiCrow wrote:
@Itix
Oh and incidently Windows 9x didn't multitask either.  It just ran background processes while waiting for mouse clicks and keystrokes.  While the foreground task was running, it hogged the processor.  

Not true. Windows 3.1 did cooperative multitasking, and Windows95 did preemptive multitasking (like AmigaOS). Lousy deceptive marketing strategy it was of M$ to call Windows 3.1 just 'multitasking', suggesting it's being equal to any other multitasking OS.

[Speelgoedmannetje]

Piru wrote:
Very limited and aged round robin scheduler. Only pre-Windows 95 and classic Mac OS are worse. Executive helps a bit by giving BSDish features.

But then, try formatting multiple floppies at the same time on a PC, or something alike. :-)

[Piru]

@Speelgoedmannetje
That's more due to ISA legacy HW, rather than windows. Playing with floppies is equally painful under linux IMO... ;-)

[Damion]

stopthegop wrote:

In Linux and Windows you can kill process at will

haha!  Welcome to Fantasy Island.  That works like maybetwo times out of ten.   Its almost always a reboot.  If I had a dime for every time I've had to reboot windoze I could retire rich, about 10 times over.  

Hmmm... maybe a hardware issue? I shut down errant processes all the time, and aside from the occasional momentary hang, it's fine. Come to think of it, I don't think I've had to reboot windows due to a (software) crash in years.



Edit--

MacOS X on the other hand, is a completely different issue. I've managed to crash it many, many times (mostly buggy apps like Safari)... of course, it may have gotten better in the last year since I gave up on it.

[Speelgoedmannetje]

Piru wrote:
@Speelgoedmannetje
That's more due to ISA legacy HW, rather than windows. Playing with floppies is equally painful under linux IMO... ;-)

I know. But also, Commodore initially chose also SCSI because it was better usable for multitasking purposes (or so I read somewhere). I mean, Amiga is multitasking in every nerve, so to say.

[Piru]

@Speelgoedmannetje

SCSI because it was better usable for multitasking purposes (or so I read somewhere).

At that point of history IDE HDDs and controllers were all PIO, that is polled by the CPU. Reading or writing something required full CPU attention. SCSI on the other hand was DMA, freeing the CPU for other tasks.

However, IDE soon gained DMA aswell. These days (with modern HW) it makes little difference from CPU usage perspective which you have. Certain specific ultra high speed applications might require SCSI still, otherwise SATA-II and RAID built with SATA devices has replaced SCSI pretty much.