OT: Unix or UNIX or unix

Gilles Gravier ggravier at fsfe.org
Fri Jun 12 06:47:38 UTC 2009


Hi, Christopher.

Christopher Chan wrote:
> Gilles Gravier wrote:
>   
>> Hi!
>>
>> Dotan Cohen wrote:
>>   
>>     
>>>> that is quite true..I get a lot of people who claim that windows is a
>>>> multi-tasking os because they can get multiple programs running at the same
>>>> time..
>>>>
>>>> i have to tell them that just because the window border changes color,
>>>> doesnt mean that it is being processed in the back ground
>>>>
>>>>     
>>>>       
>>>>         
>>> Are you serious? Windows has been a preemptive multi-tasking OS since
>>> Win98 I think, and it had some hack to fake multitasking before that.
>>> If you can link to a page which states otherwise, I'd live to be
>>> corrected.
>>>   
>>>     
>>>       
>> Not completely. In Windows, you had to use the official Windows system
>> calls which all had multitasking built in. But if you wrote a loop that did
>>
>> while (true)
>> {
>>   a=1;
>> }
>>
>> You basically hang the machine.
>>
>> Not on Unix.
>>   
>>     
>
> So Windows had a lousy process scheduler. That does not make it 
> non-multitasking does it now?
>   
It makes it non-preemptive.

Preemptive multitasking is when the scheduler can preempt a thread, stop
it, give the CPU to another, then switch again... in older windows,
threads had to give control back to the scheduler (when you did an IO /
GUI / System call, the scheduler would deschedule the current thread and
switch to another until that thread made a system call and so on).

That's what I was commenting on... the "preemptive" aspect of Windows'
scheduler.

Gilles.




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