Kernel Threads question on 2.4

Kernel Threads question on 2.4

[Akram.Abou-Emara]

Hi All,

I have a couple of questions:

Do kernel threads get preempted? Or do they have to
give up the CPU on their own? 

Are there any rules for what scheduling policies and
priority a kernel thread can have?
reparent_to_init()sets the scheduling policy to
SCHED_OTHER. Do you see a problem with changing the
scheduling policy to  SCHED_FIFO?

Thanks,
Akram

Re: Kernel Threads question on 2.4

[Robert Love]

On Mon, 2003-02-03 at 19:52, Akram.Abou-Emara@nokia.com wrote:

These questions might be better asked on the kernelnewbies list...

> Do kernel threads get preempted? Or do they have to
> give up the CPU on their own? 

Without the preemptive kernel, they are not preemptive.  With
preempt-kernel, they are.  They tend to run at elevated priorities
anyhow, so this is not so much of an issue.

> Are there any rules for what scheduling policies and
> priority a kernel thread can have?
> reparent_to_init()sets the scheduling policy to
> SCHED_OTHER. Do you see a problem with changing the
> scheduling policy to  SCHED_FIFO?

kernel threads can have any scheduling policy or priority - they really
do not differ much from regular threads (sans the lack of address
space).

Some kernel threads do indeed run with real-time policy.

	Robert Love