linux-kernel - Re: [RFC PATCH v2 4/8] tick/nohz: keep tick on for a fast idle

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Message-ID: <c64ed43d-8afe-7317-e31f-a7a5eef914d1@linux.intel.com>
Date:   Mon, 16 Oct 2017 13:34:57 +0800
From:   "Li, Aubrey" <aubrey.li@...ux.intel.com>
To:     Mike Galbraith <efault@....de>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Aubrey Li <aubrey.li@...el.com>
Cc:     tglx@...utronix.de, peterz@...radead.org, len.brown@...el.com,
        ak@...ux.intel.com, tim.c.chen@...ux.intel.com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 4/8] tick/nohz: keep tick on for a fast idle

On 2017/10/16 12:45, Mike Galbraith wrote:
> On Mon, 2017-10-16 at 11:26 +0800, Li, Aubrey wrote:
>>
>> I'll try to move quiet_vmstat() into the normal idle branch if this patch series
>> are reasonable. Is fast_idle a good indication for it?
> 
> see x86_tip 62cb1188ed86 sched/idle: Move quiet_vmstate() into the NOHZ code

It looks like this commit makes tick stop critical as it can be invoked in interrupt
exit path?

->smp_apic_timer_interrupt
-->irq_exit
--->tick_nohz_irq_exit
---->__tick_nohz_idle_enter
----->tick_nohz_stop_sched_tick
------>quiet_vmstat

Thanks,
-Aubrey