linux-kernel - Re: [PATCH 3/3] cpuidle/menu: add per cpu pm_qos_resume

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Date:   Thu, 12 Jan 2017 15:03:42 -0500
From:   Rik van Riel <riel@...hat.com>
To:     Alex Shi <alex.shi@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        vincent.guittot@...aro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Arjan van de Ven <arjan@...ux.intel.com>
Subject: Re: [PATCH 3/3] cpuidle/menu: add per cpu pm_qos_resume_latency
 consideration

On Thu, 2017-01-12 at 21:27 +0800, Alex Shi wrote:
> Kernel or user may have special requirement on cpu response time,
> like
> if a interrupt is pinned to a cpu, we don't want the cpu goes too
> deep
> sleep. This patch can prevent this thing happen by consider per cpu
> resume_latency setting in cpu sleep state selection in menu governor.
> 
> The pm_qos_resume_latency ask device to give reponse in this time.
> That's
> similar with cpu cstates' entry_latency + exit_latency. But since
> most of cpu cstate either has no entry_latency or add it into
> exit_latency
> So, we just can restrict this time requirement as states
> exit_latency.
> 
> We can set a wanted latency value according to the value of
> /sys/devices/system/cpu/cpuX/cpuidle/stateX/latency. to just a bit
> less than related state's latency value. Then cpu can get to this
> state
> or higher.
> 
> Signed-off-by: Alex Shi <alex.shi@...aro.org>
> To: linux-kernel@...r.kernel.org
> Cc: linux-pm@...r.kernel.org
> Cc: Ulf Hansson <ulf.hansson@...aro.org>
> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Rasmus Villemoes <linux@...musvillemoes.dk>
> Cc: Arjan van de Ven <arjan@...ux.intel.com>
> Cc: Rik van Riel <riel@...hat.com>
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
> 

Acked-by: Rik van Riel <riel@...hat.com>

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