Re: [PATCH 3/3] context_tracking,x86: remove extraneous irq disable & enable from context tracking on syscall entry

[Ingo Molnar <mingo@kernel.org>]

* Ingo Molnar <mingo@kernel.org> wrote:

> > 2. To suppress the timing tick, we need to get some timing for, 
> > um, the scheduler?  I wasn't really sure about this one.
> 
> So we have variable timeslice timers for the scheduler implemented, 
> they are off by default but they worked last someone tried them. See 
> the 'HRTICK' scheduler feature.
> 
> And for SCHED_FIFO that timeout can be 'never' - i.e. essentially 
> stopping the scheduler tick. (within reason.)

Also note that this bit in context_tracking_enter():

                        if (state == CONTEXT_USER) {
                                trace_user_enter(0);
                                vtime_user_enter(current);
                        }


is related to precise time measurement of user/kernel execution times, 
it's not needed by the scheduler at all, it's just exported to 
tooling. It's not fundamental to the scheduler.

Thanks,

	Ingo