linux-kernel - Re: [RFT][PATCH v7 0/8] sched/cpuidle: Idle loop rework

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Date:   Wed, 21 Mar 2018 14:55:36 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Rik van Riel <riel@...riel.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Thomas Ilsche <thomas.ilsche@...dresden.de>,
        Doug Smythies <dsmythies@...us.net>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        Mike Galbraith <mgalbraith@...e.de>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFT][PATCH v7 0/8] sched/cpuidle: Idle loop rework

On Wednesday, March 21, 2018 1:31:07 PM CET Rik van Riel wrote:
> On Tue, 2018-03-20 at 16:12 +0100, Rafael J. Wysocki wrote:
> > Hi All,
> > 
> > Thanks a lot for the feedback so far!
> > 
> > Respin after recent comments from Peter.
> > 
> > Patches [1-3] unmodified since v5, patch 4 is new and the other ones
> > have been updated to address feedback.
> > 
> > The previous summary that still applies:

Thanks for the testing!
 
> For some reason I see increased CPU utilization
> with this patch series (75% -> 85%) with the same
> rate of requests being handled by the vanilla
> kernel and a kernel with these patches applied.
> 
> I am running a bisect in the series to see what
> change could possibly cause that,

The first 4 patches in the v7 should not change functionality by
themselves.

If you replace the original [5/8] with the v7.2 of it I've just
posted (https://patchwork.kernel.org/patch/10299429/), then it
should not change functionality by itself too.

Then you only have 3 patches to check. :-)

> and also digging
> through system statistics to see whether it might
> be something as perverse as not mistakenly choosing
> deeper C-states on one core causing other cores to
> miss out on turbo mode...

I have no idea ATM.  And what's the workload?