sched_setscheduler() behaviour changed??

[Kostik Belousov]

On Thu, Feb 17, 2011 at 10:50:06AM +0100, Mats Lindberg wrote:
> All,
> I have been using a small program /rt) that utilize the sched_setscheduler()
> syscall to set the scheduling policy of a process to SCHED_RR. Been running
> it FBSD 5.x and 6.x. Now when migrating to FBSD 8.1 I get EPERM back at me.
> used to be able to run it like e.g.
> > ./rt -sr -p2 -- prog
> 
> which started <prog> in SCHED_RR policy with priority 2.
> 
> now in FBSD 8.1 I get EPERM
> 
> But If I do
> > rtprio 10 ./rt -sr -p2 -- prog
> 
> it I dont get EPERM.
> 
> I'm always root when doing this.
> 
> My problem is that I have customers that need to run their old 5.x 6.x
> applications 'as is' in 8.1 whithout changing anything.
> 
> Does anyone know if there is a workaround?
> sysctl? kernel hint? kernel config? reverting to 4BSD scheduler?

If you want help from the list, you should provide some data
to diagnose the issue. Obviously, we cannot read the sources of your
rt utility. At least, you can provide ktrace/kdump output for start.
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