On Tue, Jan 28, 2014 at 5:23 AM, Frederic Weisbecker <[email protected]> wrote: > On Fri, Jan 24, 2014 at 10:51:14AM +0530, Viresh Kumar wrote: >> On 23 January 2014 20:28, Frederic Weisbecker <[email protected]> wrote: >> > On Tue, Jan 21, 2014 at 04:03:53PM +0530, Viresh Kumar wrote: >> >> >> So, the main problem in my case was caused by this: >> >> >> >> <...>-2147 [001] d..2 302.573881: hrtimer_start: >> >> hrtimer=c172aa50 function=tick_sched_timer expires=602075000000 >> >> softexpires=602075000000 >> >> >> >> I have mentioned this earlier when I sent you attachments. I think >> >> this is somehow >> >> tied with the NO_HZ_FULL stuff? As the timer is queued for 300 seconds >> >> after >> >> current time. >> >> >> >> How to get this out? >> > >> > So it's scheduled away 300 seconds later. It might be a pending >> > timer_list. Enabling the >> > timer tracepoints may give you some clues. >> >> Trace was done with that enabled. /proc/timer_list confirms that a hrtimer >> is queued for 300 seconds later for tick_sched_timer. And so I assumed >> this is part of the current NO_HZ_FULL implementation. >> >> Just to confirm, when we decide that a CPU is running a single task and so >> can enter tickless mode, do we queue this tick_sched_timer for 300 seconds >> ahead of time? If not, then who is doing this :) > > No, when a single task is running on a full dynticks CPU, the tick is > supposed to run > every seconds. I'm actually suprised it doesn't happen in your traces, did > you tweak > something specific?
I think Viresh is using my patch/hack to configure/disable the 1Hz residual tick. Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
