linux-kernel - Re: [PATCH RFC v0 00/12] Cyclic Scheduler Against RTC

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Message-ID: <CAAmnkz=Oo+jDn05+1ECYBnYchfB8_p04SvYmrMu-GWSxBKxOBA@mail.gmail.com>
Date:	Wed, 13 Apr 2016 02:37:26 -0700
From:	"Bill Huey (hui)" <bill.huey@...il.com>
To:	Juri Lelli <juri.lelli@....com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Steven Rostedt <rostedt@...dmis.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dario Faggioli <raistlin@...ux.it>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Thomas Gleixner <tglx@...utronix.de>,
	KY Srinivasan <kys@...rosoft.com>,
	Amir Frenkel <frenkel.amir@...il.com>,
	Bdale Garbee <bdale@....com>, luca abeni <luca.abeni@...tn.it>
Subject: Re: [PATCH RFC v0 00/12] Cyclic Scheduler Against RTC

[Trying to resend this so that linux-kernel mailer doesn't reject it.
ok just found plain text mode. Will cull the CC list in future
responses]

Hi Juri,

It's not for replacing deadline first of all. I'm not fully aware of the
kind of things being done with deadline and I would like links so that I
have some kind of reference

The original motivation for doing this was for a number of reasons:

1) Current FIFO/RR policies aren't exact enough for a lot of the mixed
modern multimedia scenarios I saw working a real-world load on an Android
like system. Insufficient feedback to interactive UX tasks that include
things like jackd and pulse audio for low latency applications (music,
keyboard controllers, touch events...) across a span of tasks across the
system.

Deadline seems to be more localized to a specific application's need and
seems to be hard to use but I'm inexperienced with it. The problems would
benefit from a simpler solution.

2) The need for a scheduler to be driven by an external interrupt from a
number sources directly.

3) The need for a global view of the system so that power management
decisions can be made sensibly made in multicore systems. It's not a
scheduler alone but ideal would have more influence over power management
decision on battery powered devices, etc...

4) other reasons that should be in the docs but I got sick of writing
exhaustive documentation on the matter...

That's the best I can do for now. I need to post new version with
compilations fixes. There's a lot of problems with code regarding
portability and other issues with the initial revision.

bill