Am 24.03.2018 um 07:46 schrieb Vincent Guittot: > Hi Heiner, > > Le Friday 23 Mar 2018 à 22:28:09 (+0100), Heiner Kallweit a écrit : >> Recently I started to get the following problems with linux-next: >> >> - When working via Putty/SSH on the system the console frequently freezes >> for few seconds. Sometimes only opening a second console makes the >> first one react again. >> >> - I get "INFO: rcu_sched detected stalls on CPUs/tasks:" warnings as >> described in [1]. >> >> Bisecting the issue resulted in: >> >> 31e77c93e432dec79c7d90b888bbfc3652592741 is the first bad commit >> commit 31e77c93e432dec79c7d90b888bbfc3652592741 >> Author: Vincent Guittot <[email protected]> >> Date: Wed Feb 14 16:26:46 2018 +0100 >> >> sched/fair: Update blocked load when newly idle >> >> When NEWLY_IDLE load balance is not triggered, we might need to update >> the >> blocked load anyway. We can kick an ilb so an idle CPU will take care of >> updating blocked load or we can try to update them locally before >> entering >> idle. In the latter case, we reuse part of the nohz_idle_balance. >> >> After reversing this commit at least the issue with the freezing console >> is gone. The second one appeared only sporadically, I still have to see >> whether it pops up again. >> > > Can you check if the change below fix the problem ? > Thanks for the quick feedback. The change however didn't fix the probem, I didn't notice any changed behavior.
> --- > kernel/sched/fair.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 3582117..672f212 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -9430,6 +9430,9 @@ static bool _nohz_idle_balance(struct rq *this_rq, > unsigned int flags, > > has_blocked_load |= update_nohz_stats(rq, true); > > + if (flags == NOHZ_STATS_KICK) > + continue; > + > /* > * If time for next balance is due, > * do the balance. >
