Re: [PATCH] kthread: run kthreadd with max priority SCHED_FIFO


On Sat, 2007-12-22 at 02:52 -0800, Andrew Morton wrote:
On Sat, 22 Dec 2007 11:39:30 +0100 Mike Galbraith <efault@xxxxxx> wrote:


On Sat, 2007-12-22 at 04:52 -0500, Jon Masters wrote:

So, user tasks running with SCHED_FIFO should be able to lock a system?
I guess I see both sides of this argument - yes, it's userspace at
fault, but in other cases when userspace is at fault, we take action
(OOM, segfault, others). Isn't this situation just another case where
the kernel needs to avoid the evils of userland going awry?

FYI, Ingo queued the below.

http://lkml.org/lkml/2007/10/31/344


That's pretty different of course, but rlimit might be a suitable interface
for implementing RLIMIT_MAX_CONTINUOUS_RT_MILLISECONDS.

I'd extend Peter's rt safety net instead: mark for forced requeue when
the soft limit is hit, or add that as an intermediate stage. Possibly
add a demotion stage as well. I wouldn't try to select lower priority
tasks, which RLIMIT_MAX_CONTINUOUS_RT_MILLISECONDS implies to me.

-Mike

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