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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Wed, 28 Mar 2018 12:56:42 +0200
Message-ID: <CAJZ5v0h40DDZ5da7CS4702Z=D3bY7SsOhbUqPR44qVKU0E4D4A@mail.gmail.com>
Subject: Re: [RFT][PATCH v7 6/8] sched: idle: Select idle state before
 stopping the tick
To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     Thomas Ilsche <thomas.ilsche@tu-dresden.de>,
        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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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:
>>>

[cut]

>
> 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.

And with a C program I see data->next_timer_us greater than TICK_USEC
while it is running, so let me dig deeper.