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

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Message-ID: <20170712213240.GE3441@tassilo.jf.intel.com>
Date:   Wed, 12 Jul 2017 14:32:40 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
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,
        arjan@...ux.intel.com, paulmck@...ux.vnet.ibm.com,
        yang.zhang.wz@...il.com, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods

On Wed, Jul 12, 2017 at 10:34:10AM +0200, Peter Zijlstra wrote:
> On Wed, Jul 12, 2017 at 12:15:08PM +0800, Li, Aubrey wrote:
> > Okay, the difference is that Mike's patch uses a very simple algorithm to make the decision.
> 
> No, the difference is that we don't end up with duplication of a metric
> ton of code.

What do you mean? There isn't much duplication from the fast path
in Aubrey's patch kit.

It just moves some code around from the cpuidle governor to be generic,
that accounts for the bulk of the changes. It's just moving however,
not adding.

> It uses the normal idle path, it just makes the NOHZ enter fail.

Which is only a small part of the problem.

-Andi