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

Ingo Molnar
2007-04-14T17:54:48Z

* 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