Messages in this thread | | | Date | Wed, 23 Feb 2011 12:35:01 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 2/2] sched: allow users with rtprio rlimit to change from SCHED_IDLE policy |
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* Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, 2011-02-23 at 12:13 +0100, Ingo Molnar wrote: > > * Peter Zijlstra <peterz@infradead.org> wrote: > > > > > On Tue, 2011-02-22 at 13:04 -0800, Darren Hart wrote: > > > > As it stands, users with rtprio rlimit permissions can change their policy from > > > > SCHED_OTHER to SCHED_FIFO and back. They can change to SCHED_IDLE, but not back > > > > to SCHED_FIFO. If they have the rtprio permission, they should be able to. Once > > > > in SCHED_FIFO, they could go back to SCHED_OTHER. This patch allows users with > > > > rtprio permission to change out of SCHED_IDLE. > > > > > > > > > > Ingo, can you remember the rationale for this? > > > > > > The fact is that SCHED_IDLE is very near nice-20, and we can do: > > > > > > peterz@twins:~$ renice 5 -p $$ > > > 1867: old priority 0, new priority 5 > > > peterz@twins:~$ renice 0 -p $$ > > > 1867: old priority 5, new priority 0 > > > > > > Which would suggest that we should be able to return to SCHED_OTHER > > > RLIMIT_NICE-20. > > > > I dont remember anything subtle there - most likely we just forgot about that spot > > when adding RLIMIT_RTPRIO support. > > Ah, I was arguing we should allow it regardless of RLIMIT_RTPRIO, based on > RLIMIT_NICE, it is after all a change to SCHED_OTHER, not SCHED_FIFO/RR.
Sure. We just went for the most restrictive conditions - it's hard to add security holes that way ;-)
Ingo
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