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Message-ID: <20161028072949.GQ3102@twins.programming.kicks-ass.net>
Date: Fri, 28 Oct 2016 09:29:49 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Vikram Mulukutla <markivx@...eaurora.org>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
Srivatsa Vaddagiri <vatsa@...eaurora.org>,
Steve Muckle <steve.muckle@...aro.org>,
Olav Haugan <ohaugan@...eaurora.org>,
Syed Rameez Mustafa <rameezmustafa@...eaurora.org>,
Joonwoo Park <joonwoop@...eaurora.org>,
Pavankumar Kondeti <pkondeti@...eaurora.org>,
Saravana Kannan <skannan@...eaurora.org>,
Bryan Huntsman <bryanh@...eaurora.org>,
Juri Lelli <juri.lelli@....com>,
Morten Rasmussen <morten.rasmussen@....com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Chris Redpath <chris.redpath@....com>,
Robin Randhawa <robin.randhawa@....com>,
Patrick Bellasi <patrick.bellasi@....com>,
Todd Kjos <tkjos@...gle.com>,
Srinath Sridharan <srinathsr@...gle.com>,
Andres Oportus <andresoportus@...gle.com>,
Leo Yan <leo.yan@...aro.org>,
Vincent Guittot <vincent.guittot@...aro.org>,
Vikram Mulukutla <markivx@...eauorora.org>
Subject: Re: [RFC PATCH 0/3] sched: Introduce Window Assisted Load Tracking
On Fri, Oct 28, 2016 at 12:10:39AM -0700, Vikram Mulukutla wrote:
>
> We propose Window-Assisted Load Tracking (WALT) as an alternative or additional
> load tracking scheme in lieu of or along with PELT, one that in our estimation
> better tracks task demand and CPU utilization especially for use cases on
> mobile devices. WALT was conceived by Srivatsa Vaddagiri to provide better
> perf-per-watt numbers on asymmetric CPU (frequency and/or IPC) implementations,
> (specifically on Qualcomm Snapgdragon chipsets running Android) and its metrics
> have been used to guide task placement and p-state selection (load balancing
> in CFS still uses PELT statistics). WALT is now present in the android-common
> kernel as well.
And how come we only learn of it after its already shipping? Isn't that
arse backwards?
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