Am 11.04.2018 um 19:00 schrieb Vincent Guittot: > Hi Heiner, > > On 9 April 2018 at 19:33, Heiner Kallweit <hkallwe...@gmail.com> wrote: >> Am 06.04.2018 um 18:03 schrieb Vincent Guittot: >>> Hi Heiner, >>> >>> On 30 March 2018 at 10:37, Heiner Kallweit <hkallwe...@gmail.com> wrote: >>>> Am 30.03.2018 um 08:50 schrieb Vincent Guittot: >>>>> On 29 March 2018 at 19:40, Heiner Kallweit <hkallwe...@gmail.com> wrote: >>>>>> Am 29.03.2018 um 09:41 schrieb Vincent Guittot: >>>>> >>>>>>> >>>>>>> I'm finally not so sure that i have the right set up to reproduce the >>>>>>> problem as I haven't been able to reproduce it since. >>>>>>> >>>>>>> Heiner, >>>>>>> >>>>>>> How fast the problem happens on your board ? >>>>>>> Are you doing anything specific on the console that trigger the problem >>>>>>> ? >>>>>>> >>>>>> Hi Vincent, >>>>>> >>>>>> the lag when working on the console is constantly there, the "rcu_preempt >>>>>> detected stalls" happens after several hours (so far always within 24h) >>>>>> w/o any triggering event I would be aware of. It occured also when the >>>>>> system was idle at that point in time. >>>>> >>>>> Ok, so I don't have the problem on my hikey as the console never lag >>>>> on my setup. >>>>> >>>>> Can you send me the config of your kernel ? I'd like to check if you >>>>> have enable something that could trigger such problem >>>>> >>>> Sure, he we go. I also add a system log. >>> >>> Thanks for the config. I have used it for my setup but I can't >>> reproduce your regression. My platforms stay stable so I probably >>> missing something. Are you facing similar problem with other platforms >>> or only this celeron based platform ? >>> >>> I have reviewed the code but don't see any obvious place in the patch >>> that can generate the problem. Nevertheless, would you mind to try the >>> patch below ? It's a blind test to try to narrow the problem. >>> >>> Thanks >>> >> Hi Vincent, >> >> I tried again with today's linux-next and it's much better. The lag isn't >> completely gone but it's much less annoying. Every ~30 secs the console >> hangs for about half a second, that's much less frequent than before. > > That's interesting because nothing related to commit > 31e77c93e432dec79c7d90b888bbfc3652592741 has been merged recently > AFAICT > >> >> I saw some patches from Rafael have been merged in the last days. >> Maybe they improved the situation. > > Yes, Peter mentions in another thread that lastest Rafael's patches > avoid stopping tick when entering short idle thus reducing the time to > enter idle. commit 31e77 is adding some background activity when > entering idle so it can be that we take too much time > > You also mentioned that the CPU was relatively slow on the platform. > Can you try to use cpufreq performance governor instead of ondemand ? >
The system uses intel_pstate scaling driver, so only powersave and performance are available. Min/max frequency are 600MHz / 1100 MHz. I didn't really notice a difference when switching between both modes. Regards, Heiner > I'm also going to prepare a patch for adding some trace in the code to > highlight the problem > > Thanks, > Vincent > >> >> Regards, Heiner >> > > [snip] > >> >
