linux-kernel - RE: [RFT][PATCH v5 0/7] sched/cpuidle: Idle loop rework

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Date:   Sat, 17 Mar 2018 09:11:53 -0700
From:   "Doug Smythies" <dsmythies@...us.net>
To:     "'Thomas Ilsche'" <thomas.ilsche@...dresden.de>,
        "'Rafael J. Wysocki'" <rjw@...ysocki.net>,
        "'Peter Zijlstra'" <peterz@...radead.org>,
        "'Linux PM'" <linux-pm@...r.kernel.org>,
        "'Frederic Weisbecker'" <fweisbec@...il.com>
Cc:     "'Thomas Gleixner'" <tglx@...utronix.de>,
        "'Paul McKenney'" <paulmck@...ux.vnet.ibm.com>,
        "'Rik van Riel'" <riel@...riel.com>,
        "'Aubrey Li'" <aubrey.li@...ux.intel.com>,
        "'Mike Galbraith'" <mgalbraith@...e.de>,
        "'LKML'" <linux-kernel@...r.kernel.org>,
        "Doug Smythies" <dsmythies@...us.net>
Subject: RE: [RFT][PATCH v5 0/7] sched/cpuidle: Idle loop rework

On 2018.03.17 Thomas Ilsche wrote:

> Over the last week I tested v4+pollv2 and now v5+pollv3. With v5, I
> observe a particular idle behavior, that I have not seen before with
> v4. On a dual-socket Skylake system the idle power increases from
> 74.1 W (system total) to 85.5 W with a 300 HZ build and even to
> 138.3 W with a 1000 HZ build. A similar Haswell-EP system is also
> affected.

I confirm your idle findings. There is a regression between V4 and V5.
The differences on my test computer are much less than on yours,
probably because I have only 8 CPUs.

http://fast.smythies.com/rjw_idle.png

1000 Hz kernel only.

... Doug