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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Leo Yan <leo.yan@linaro.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
	Rafael Wysocki <rafael.j.wysocki@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux PM <linux-pm@vger.kernel.org>
Subject: Re: [RESEND PATCH v1 1/2] cpuidle: menu: Correct the criteria for stopping tick
Date: Mon, 13 Aug 2018 10:01:20 +0200
Message-ID: <CAJZ5v0g-ZaUe1AJ=4tixtacaGB-roMXLXj5HNHBqMk+jf3aYnA@mail.gmail.com> (raw)
In-Reply-To: <20180812160740.GC28966@leoy-ThinkPad-X240s>

On Sun, Aug 12, 2018 at 6:07 PM <leo.yan@linaro.org> wrote:
>
> On Sun, Aug 12, 2018 at 01:12:41PM +0200, Rafael J. Wysocki wrote:
> > On Fri, Aug 10, 2018 at 11:03 AM <leo.yan@linaro.org> wrote:

[cut]

> >
> > Assuming shot noise wakeups, if
> > drv->states[drv->state_count-1].target_residency is less than
> > TICK_USEC, the tick will be stopped for CPUs more often on average
> > with the patch applied (simply because the idle duration range for
> > which it will not be stopped is narrower then).
>
> Yes, good point, so in the new approach I try to change the code
> to compare with next tick delta rather than TICK_USEC, it can keeps
> running tick for the tick with long expire time (similiar with
> comparing with TICK_USEC) but we also can stop tick if the tick is likely
> to break idle residency.

We tried something similar and the results were not encouraging.
Please see https://lore.kernel.org/lkml/079e16b6-2e04-2518-0553-66becab226a6@tu-dresden.de/

  reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-09 17:20 [RESEND PATCH v1 0/2] Optimization CPU idle state impacted by tick Leo Yan
2018-08-09 17:20 ` [RESEND PATCH v1 1/2] cpuidle: menu: Correct the criteria for stopping tick Leo Yan
2018-08-09 20:47   ` Rafael J. Wysocki
2018-08-10  7:13     ` leo.yan
2018-08-10  7:22       ` Rafael J. Wysocki
2018-08-10  8:49         ` leo.yan
2018-08-10  9:03           ` leo.yan
2018-08-12 11:12             ` Rafael J. Wysocki
2018-08-12 16:07               ` leo.yan
2018-08-13  8:01                 ` Rafael J. Wysocki [this message]
2018-08-13  9:58                   ` leo.yan
2018-08-09 17:20 ` [RESEND PATCH v1 2/2] cpuidle: menu: Dismiss tick impaction on correction factors Leo Yan
2018-08-09 21:06   ` Rafael J. Wysocki

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