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

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Message-ID: <91d02dce-7a3c-371c-a247-55fce1e7124a@linux.intel.com>
Date:   Mon, 17 Jul 2017 12:27:56 -0700
From:   Arjan van de Ven <arjan@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Andi Kleen <ak@...ux.intel.com>
Cc:     "Li, Aubrey" <aubrey.li@...ux.intel.com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Christoph Lameter <cl@...ux.com>,
        Aubrey Li <aubrey.li@...el.com>, tglx@...utronix.de,
        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 7/17/2017 12:23 PM, Peter Zijlstra wrote:
> Now I think the problem is that the current predictor goes for an
> average idle duration. This means that we, on average, get it wrong 50%
> of the time. For performance that's bad.

that's not really what it does; it looks at next tick
and then discounts that based on history;
(with different discounts for different order of magnitude)