linux-kernel - Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods

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Message-ID: <20170718170511.m73o7ee2izsy6u66@hirez.programming.kicks-ass.net>
Date:   Tue, 18 Jul 2017 19:05:11 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Arjan van de Ven <arjan@...ux.intel.com>
Cc:     paulmck@...ux.vnet.ibm.com,
        "Li, Aubrey" <aubrey.li@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andi Kleen <ak@...ux.intel.com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Christoph Lameter <cl@...ux.com>,
        Aubrey Li <aubrey.li@...el.com>, len.brown@...el.com,
        rjw@...ysocki.net, tim.c.chen@...ux.intel.com,
        yang.zhang.wz@...il.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, daniel.lezcano@...aro.org
Subject: Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods

On Tue, Jul 18, 2017 at 09:37:57AM -0700, Arjan van de Ven wrote:

> that's just a matter of fixing the C1 and later thresholds to line up right.
> shrug that's the most trivial thing to do, it's a number in a table.

Well, they represent a physical measure, namely the break-even-time. If
you go muck with them you don't have anything left.  This is tinkering
of the worst possible kind.

Fix the estimator if you want behavioural changes.

> some distros do those tunings anyway when they don't like the upstream tunings

*shudder*