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

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Date:   Mon, 17 Jul 2017 21:59:43 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Arjan van de Ven <arjan@...ux.intel.com>
cc:     Peter Zijlstra <peterz@...radead.org>,
        Andi Kleen <ak@...ux.intel.com>,
        "Li, Aubrey" <aubrey.li@...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,
        paulmck@...ux.vnet.ibm.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 Mon, 17 Jul 2017, Arjan van de Ven wrote:
> On 7/17/2017 12:46 PM, Thomas Gleixner wrote:
> > That's where Daniel Lezcanos work of predicting interrupts comes in and
> > that's the right solution to the problem. The core infrastructure has been
> > merged, just the idle/cpufreq users are not there yet. All you need to do
> > is to select CONFIG_IRQ_TIMINGS and use the statistics generated there.
> > 
> yes ;-)

:)

> also note that the predictor does not need to perfect, on most systems C
> states are an order of magnitude apart in terms of
> power/performance/latency so if you get the general order of magnitude
> right the predictor is doing its job.

So it would be interesting just to enable the irq timings stuff and compare
the outcome as a first step. That should be reasonably simple to implement
and would give us also some information of how that code behaves on larger
systems.

Thanks,

	tglx