linux-kernel - RE: [RFT][PATCH v7.3 5/8] cpuidle: Return nohz hint from cpuidle

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Date:   Thu, 22 Mar 2018 13:46:49 -0700
From:   "Doug Smythies" <dsmythies@...us.net>
To:     "'Rafael J. Wysocki'" <rjw@...ysocki.net>
Cc:     "'Frederic Weisbecker'" <fweisbec@...il.com>,
        "'Thomas Gleixner'" <tglx@...utronix.de>,
        "'Paul McKenney'" <paulmck@...ux.vnet.ibm.com>,
        "'Thomas Ilsche'" <thomas.ilsche@...dresden.de>,
        "'Rik van Riel'" <riel@...riel.com>,
        "'Aubrey Li'" <aubrey.li@...ux.intel.com>,
        "'Mike Galbraith'" <mgalbraith@...e.de>,
        "'LKML'" <linux-kernel@...r.kernel.org>,
        "'Linux PM'" <linux-pm@...r.kernel.org>,
        "'Peter Zijlstra'" <peterz@...radead.org>
Subject: RE: [RFT][PATCH v7.3 5/8] cpuidle: Return nohz hint from cpuidle_select()

On 2018.03.22 10:40 Rafael J. Wysocki wrote:

...[snip]...

>The difference between this and the original v7 (of patch [5/8]) is
> what happens in menu_update().  This time next_timer_us is checked
> properly and if that is above the tick boundary and a tick wakeup occurs,
> the function simply sets mesured_us to a large constant and uses that to
> update both the correction factor and data->intervals[] (the particular
> value used in this patch was found through a bit of experimentation).
>
> Let's see how this works for Thomas and Doug.

System idle test done for 74 minutes.
After boot and after the system settles down for a couple of minutes,
Processor package power is constant at 3.7 Watts. (great)
Not worth a new graph to show a flat line.

V7.3 average package power = 3.68 Watts.
V7 average package power = 3.68 Watts
V7.2+ average package power = 4.06 Watts (+10%)

> For easier testing there is a git branch containing this patch (and the
> rest of the series) at:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
>  idle-loop-v7.3

Thanks. I used this git branch this time and for the first time.
Much easier.

... Doug