David Olofson wrote:
>
> Wed, 22 Mar 2000 [EMAIL PROTECTED] wrote:
> > (BTW: from the Linux man page:
> > As SCHED_FIFO and SCHED_RR processes can preempt
> > other processes forever, only root processes are allowed to activate these
> > policies under Linux.
> > )
>
> Yep, you have to have *some* kind of adrenaline rush left with protected memory
> and all! ;-) If you want to be completely safe, you could always throw in a
> watchdog thread or something...
The watchdog thread would be preempted as well. If Linux does
SCHED_FIFO and SCHED_RR by turning off interrupts, then even setting a
timer interrupt will not work. The only option may be to have a
hardware COP watchdog card in the PC.
I was thinking Magic SysRq key to kill the
> current (SCHED_FIFO or SCHED_RR) thread as another alternative, but I might be
> missing something that already exists.
>
> And as for the root privileges requirement, it has been discussed adding a
> "real time" user group capability instead. (I'm not up to date with this,
> though.) Running RT apps as root just for the scheduling is not all that nice in
> production systems, especially not if they are going to run user installed
> third-party plugins in those threads...
Only your scheduler has to be root. Your scheduler is responsible for
changing the policy for a process. Only that process will have its
policy changed. Any processes that your scheduler controls can be in
user space.
Read the man page for sched_setscheduler.
- Kal.
>
> Regards,
>
> //David
>
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