Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS]

[Ingo Molnar <mingo@elte.hu>]

* Eric W. Biederman <ebiederm@xmission.com> wrote:

> > Thinking about it, I don't know if there are calls to schedule() 
> > while switching from tty1 to tty2. Alt-F2 had no effect anymore, and 
> > "chvt 2" simply blocked. It would have been possible that a 
> > schedule() call somewhere got starved due to the load, I don't know.
> 
> It looks like there is a call to schedule_work.

so this goes over keventd, right?

> There are two pieces of the path. If you are switching in and out of a 
> tty controlled by something like X.  User space has to grant 
> permission before the operation happens.  Where there isn't a gate 
> keeper I know it is cheaper but I don't know by how much, I suspect 
> there is still a schedule happening in there.

Could keventd perhaps be starved? Willy, to exclude this possibility, 
could you perhaps chrt keventd to RT priority? If events/0 is PID 5 then 
the command to set it to SCHED_FIFO:50 would be:

  chrt -f -p 50 5

but ... events/0 is reniced to -5 by default, so it should definitely 
not be starved.

	Ingo
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