Messages in this thread | | | Date | Fri, 12 Dec 2014 17:17:03 +0530 | From | Preeti U Murthy <> | Subject | Re: [Query] Spurious interrupts from clockevent device on X86 Ivybridge |
| |
On 12/11/2014 10:26 AM, Santosh Shukla wrote: > On 11 December 2014 at 10:14, Preeti U Murthy <preeti@linux.vnet.ibm.com> wrote: >> On 12/10/2014 06:22 PM, Viresh Kumar wrote: >>> On 10 December 2014 at 18:03, Preeti U Murthy <preeti@linux.vnet.ibm.com> wrote: >>> >>>> Right. We get an interrupt when nobody had asked for it to be delivered >>>> or had asked for it to be delivered and later canceled the request. It >>>> is most often in the latter situation, that there can be race >>>> conditions. If these race conditions are not taken care of, they can >>>> result in spurious interrupts. >>> >>> But the delta time will be very small then, right ? >> >> I was talking of the case where we get an interrupt from the clockevent >> device but dont find the hrtimer to service and not really of an anomaly >> in timekeeping. >> For instance one of the issues that we had seen earlier wherein we >> cancel the tick-sched-timer before going tickless, but since we had >> programmed the clock event device to fire, we get a spurious interrupt. >> > > I verified this case before reporting; In my case tick_sched_timer do > get cancelled before expire duration but then clk_evt_device get > reprogrammed for next time node in list. __remove_hrtimer() takes > care of that.
Right. The scenario I described happens in the Low Resolution Mode. You are right, this does not happen in the High Resolution Mode.
Regards Preeti U Murthy
| |