From: Juri Lelli <juri.lelli@arm.com>
To: "Bill Huey (hui)" <bill.huey@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Steven Rostedt <rostedt@goodmis.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Dario Faggioli <raistlin@linux.it>,
Alessandro Zummo <a.zummo@towertech.it>,
Thomas Gleixner <tglx@linutronix.de>,
KY Srinivasan <kys@microsoft.com>,
Amir Frenkel <frenkel.amir@gmail.com>,
Bdale Garbee <bdale@gag.com>, luca abeni <luca.abeni@unitn.it>
Subject: Re: [PATCH RFC v0 00/12] Cyclic Scheduler Against RTC
Date: Wed, 13 Apr 2016 11:08:39 +0100 [thread overview]
Message-ID: <20160413100839.GH5609@e106622-lin> (raw)
In-Reply-To: <CAAmnkz=Oo+jDn05+1ECYBnYchfB8_p04SvYmrMu-GWSxBKxOBA@mail.gmail.com>
On 13/04/16 02:37, Bill Huey (hui) wrote:
> [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
>
OK. You can find references in Documentation, in my first reply and
embedded in the ELC slides as well. Please, let me know if you need more
:-).
> 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.
>
I'm not sure what you mean by "localized", but I believe DEADLINE should
be used more widely to service the same kind of applications you are
referring to. It's still a quite new addition to the scheduler, so it is
understandable that we still have some legacy to fight. But we can get
better in the future.
> 2) The need for a scheduler to be driven by an external interrupt from a
> number sources directly.
>
If you use DEADLINE to service the activity an interrupt source might
trigger, I think you can already do this.
> 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...
>
That's true. But it is also already something we currently are working on.
I don't know if you are following the schedfreq/schedutil threads [1], for
example, but there we are discussing how to integrate scheduler and
cpufreq more closely. And you might also be interested in the EAS effort
[2].
> 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.
>
OK. Feel free to ask if you also decide to experiment with DEADLINE and
find any problem with it.
Best,
- Juri
[1] https://lkml.org/lkml/2016/3/17/420
https://lkml.org/lkml/2016/2/22/1037
[2] https://lkml.org/lkml/2015/7/7/754
next prev parent reply other threads:[~2016-04-13 10:07 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-12 5:29 Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 01/12] Kconfig change Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 02/12] Reroute rtc update irqs to the cyclic scheduler handler Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 03/12] Add cyclic support to rtc-dev.c Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 04/12] Anonymous struct initialization Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 05/12] Task tracking per file descriptor Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 06/12] Add anonymous struct to sched_rt_entity Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 07/12] kernel/userspace additions for addition ioctl() support for rtc Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 08/12] Compilation support Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 09/12] Add priority support for the cyclic scheduler Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 10/12] Export SCHED_FIFO/RT requeuing functions Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 11/12] Cyclic scheduler support Bill Huey (hui)
2016-04-12 5:29 ` [PATCH RFC v0 12/12] Cyclic/rtc documentation Bill Huey (hui)
2016-04-12 5:58 ` [PATCH RFC v0 00/12] Cyclic Scheduler Against RTC Mike Galbraith
[not found] ` <CAAmnkz=X4TtY7LQwPuWWD0q99XeZQT+53RZ_7dNb3P=X=+jxrg@mail.gmail.com>
2016-04-12 6:05 ` Mike Galbraith
2016-04-13 8:57 ` Juri Lelli
2016-04-13 9:37 ` Bill Huey (hui)
2016-04-13 10:08 ` Juri Lelli [this message]
2016-04-13 10:35 ` Bill Huey (hui)
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