From: Vincent Guittot <vincent.guittot@linaro.org>
To: Heiner Kallweit <hkallweit1@gmail.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Problem with commit 31e77c93e432 "sched/fair: Update blocked load when newly idle"
Date: Sat, 24 Mar 2018 07:46:27 +0100 [thread overview]
Message-ID: <20180324064627.GA10884@linaro.org> (raw)
In-Reply-To: <e1da0be1-94d8-d5d0-8329-4507c51ddd64@gmail.com>
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
next prev parent reply other threads:[~2018-03-24 6:46 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-23 21:28 Problem with commit 31e77c93e432 "sched/fair: Update blocked load when newly idle" Heiner Kallweit
2018-03-24 6:46 ` Vincent Guittot [this message]
2018-03-24 12:47 ` Heiner Kallweit
2018-03-28 10:37 ` Dietmar Eggemann
2018-03-28 14:01 ` Vincent Guittot
2018-03-29 7:41 ` Vincent Guittot
2018-03-29 17:40 ` Heiner Kallweit
2018-03-30 6:50 ` Vincent Guittot
2018-03-30 8:37 ` Heiner Kallweit
2018-04-06 16:03 ` Vincent Guittot
2018-04-06 19:53 ` Heiner Kallweit
2018-04-09 17:33 ` Heiner Kallweit
2018-04-11 17:00 ` Vincent Guittot
2018-04-11 20:35 ` Heiner Kallweit
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