| From: |
| Peter Zijlstra <peterz-AT-infradead.org> |
| To: |
| Vikram Mulukutla <markivx-AT-codeaurora.org> |
| Subject: |
| Re: [RFC PATCH 0/3] sched: Introduce Window Assisted Load Tracking |
| Date: |
| Fri, 28 Oct 2016 09:29:49 +0200 |
| Message-ID: |
| <20161028072949.GQ3102@twins.programming.kicks-ass.net> |
| Cc: |
| linux-kernel-AT-vger.kernel.org, Ingo Molnar <mingo-AT-kernel.org>, Srivatsa Vaddagiri <vatsa-AT-codeaurora.org>, Steve Muckle <steve.muckle-AT-linaro.org>, Olav Haugan <ohaugan-AT-codeaurora.org>, Syed Rameez Mustafa <rameezmustafa-AT-codeaurora.org>, Joonwoo Park <joonwoop-AT-codeaurora.org>, Pavankumar Kondeti <pkondeti-AT-codeaurora.org>, Saravana Kannan <skannan-AT-codeaurora.org>, Bryan Huntsman <bryanh-AT-codeaurora.org>, Juri Lelli <juri.lelli-AT-arm.com>, Morten Rasmussen <morten.rasmussen-AT-arm.com>, Dietmar Eggemann <dietmar.eggemann-AT-arm.com>, Chris Redpath <chris.redpath-AT-arm.com>, Robin Randhawa <robin.randhawa-AT-arm.com>, Patrick Bellasi <patrick.bellasi-AT-arm.com>, Todd Kjos <tkjos-AT-google.com>, Srinath Sridharan <srinathsr-AT-google.com>, Andres Oportus <andresoportus-AT-google.co |
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?
