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From: Vincent Guittot <vincent.guittot@linaro.org>
To: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
	"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: Fri, 30 Mar 2018 08:50:22 +0200	[thread overview]
Message-ID: <CAKfTPtD17yUrp5G7gPN6ijB+C-TKJcK1UTCmP_JhMK5DvSDN_g@mail.gmail.com> (raw)
In-Reply-To: <796bbd7b-8512-7370-28c9-0f082dc3f287@gmail.com>

On 29 March 2018 at 19:40, Heiner Kallweit <hkallweit1@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

Thanks,
Vincent

>
> Rgds, Heiner
>
>> Regards,
>> Vincent
>>
>>>>
>>>>>>> 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.
>>>>
>>>>
>>>> [...]
>>>>
>>
>

  reply	other threads:[~2018-03-30  6:50 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
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 [this message]
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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