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Subject: Re: [RFT][PATCH v7 6/8] sched: idle: Select idle state before
 stopping the tick
To:     "Rafael J. Wysocki" <rafael@kernel.org>
CC:     Peter Zijlstra <peterz@infradead.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        "Thomas Gleixner" <tglx@linutronix.de>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Doug Smythies <dsmythies@telus.net>,
        Rik van Riel <riel@surriel.com>,
        "Aubrey Li" <aubrey.li@linux.intel.com>,
        Mike Galbraith <mgalbraith@suse.de>,
        LKML <linux-kernel@vger.kernel.org>
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From:   Thomas Ilsche <thomas.ilsche@tu-dresden.de>
Message-ID: <ceb8f46f-6bcd-a07e-beb4-b34a9810ad8d@tu-dresden.de>
Date:   Wed, 28 Mar 2018 17:15:11 +0200
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On 2018-03-28 12:56, Rafael J. Wysocki wrote:
> On Wed, Mar 28, 2018 at 12:37 PM, Rafael J. Wysocki <rafael@kernel.org>=
 wrote:
>> On Wed, Mar 28, 2018 at 10:38 AM, Thomas Ilsche
>> <thomas.ilsche@tu-dresden.de> wrote:
>>> On 2018-03-28 10:13, Rafael J. Wysocki wrote:
>>>>
>=20
> [cut]
>=20
>>
>> So I do
>>
>> $ for cpu in 0 1 2 3; do taskset -c $cpu sh -c 'while true; do usleep
>> 500; done' & done
>>
>> which is a shell kind of imitation of the above and I cannot see this
>> issue at all.
>>
>> I count the number of times data->next_timer_us in menu_select() is
>> greater than TICK_USEC and while this "workload" is running, that
>> number is exactly 0.
>>
>> I'll try with a C program still.
>=20
> And with a C program I see data->next_timer_us greater than TICK_USEC
> while it is running, so let me dig deeper.
>=20

I can confirm that a shell-loop behaves differently like you describe.
Even if it's just a shell-loop calling "main{usleep(500);}" binary.


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