Re: Linux Kernel constraints!

Vojtech Pavlik (vojtech-lists@twilight.ucw.cz)
Thu, 21 Jan 1999 20:35:10 +0100


On Thu, Jan 21, 1999 at 11:38:55AM +0530, Yogesh Bansal wrote:

> Recently(dec.) in WindowsNT magazine comparisons/similarities between
> various flavours of unix and nt had come. In the same article Linux was
> ignored as enterprise os on account of following kernel 'limitations' :

As far as I know:

> 1. kernel is not preemptive. ie even a higher priority user thread cant
> cause another thread to be swapped if the other thread is presently running
> in privileged/kernel context.

What is meant by 'swapped'? I assume it's that the CPU is taken away from
the running task(/thread). Then yes, this is true, but only would be a
problem if the kernel call would take very long time.

> 2. kernel is not reentrant. ie.only one thread in kernel context at a time.

True only for <= 2.0 kernels.

> 3. kernel is not multi processing in the sense that on multiprocessor
> systems it will run on only one cpu at a time.

True only ofr <= 2.0 kernels.

> will somebody can clarify these doubts and version which enabled it to be
> otherwise.

Hmm, I may be wrong. If I am, anyone correct me.

Vojtech

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