Re: [PATCH RFC] clocksource: Detect a watchdog overflow

2016-04-07 Thread John Stultz
On Thu, Apr 7, 2016 at 1:14 AM, Gratian Crisan wrote: > John Stultz writes: >> So I'm sympathetic to this issue, because I remember seeing similar >> problems w/ runaway SCHED_FIFO tasks w/ PREEMPT_RT. > > Yeah, a runaway rt thread can easily do it. That's just bad design. In > our case it was a b

Re: [PATCH RFC] clocksource: Detect a watchdog overflow

2016-04-07 Thread Gratian Crisan
John Stultz writes: > On Tue, Mar 15, 2016 at 11:50 AM, Gratian Crisan > wrote: >> The clocksource watchdog can falsely trigger and disable the main >> clocksource when the watchdog wraps around. >> >> The reason is that an interrupt storm and/or high priority (FIFO/RR) tasks >> can preempt the

Re: [PATCH RFC] clocksource: Detect a watchdog overflow

2016-04-06 Thread John Stultz
On Tue, Mar 15, 2016 at 11:50 AM, Gratian Crisan wrote: > The clocksource watchdog can falsely trigger and disable the main > clocksource when the watchdog wraps around. > > The reason is that an interrupt storm and/or high priority (FIFO/RR) tasks > can preempt the timer softirq long enough for t

[PATCH RFC] clocksource: Detect a watchdog overflow

2016-03-15 Thread Gratian Crisan
The clocksource watchdog can falsely trigger and disable the main clocksource when the watchdog wraps around. The reason is that an interrupt storm and/or high priority (FIFO/RR) tasks can preempt the timer softirq long enough for the watchdog to wrap around if it has a limited number of bits avai