Messages in this thread Patch in this message | | | Date | Sat, 24 Mar 2018 07:46:27 +0100 | From | Vincent Guittot <> | Subject | Re: Problem with commit 31e77c93e432 "sched/fair: Update blocked load when newly idle" |
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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 <vincent.guittot@linaro.org> > 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 ?
--- 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. -- > System is a Zotac CI321 mini PC with Intel Celeron 2961Y CPU. > If you need more details, please let me know. > > Regards, Heiner > > [1] https://lkml.org/lkml/2018/3/22/605
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