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

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Message-ID: <1460440715.3839.101.camel@gmail.com>
Date:	Tue, 12 Apr 2016 07:58:35 +0200
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	"Bill Huey (hui)" <bill.huey@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Steven Rostedt <rostedt@...dmis.org>,
	linux-kernel@...r.kernel.org
Cc:	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>
Subject: Re: [PATCH RFC v0 00/12] Cyclic Scheduler Against RTC

On Mon, 2016-04-11 at 22:29 -0700, Bill Huey (hui) wrote:
> Hi,
> 
> This a crude cyclic scheduler implementation. It uses SCHED_FIFO tasks
> and runs them according to a map pattern specified by a 64 bit mask. Each
> bit corresponds to an entry into an 64 entry array of
> 'struct task_struct'. This works single core CPU 0 only for now.
> 
> Threads are 'admitted' to this map by an extension to the ioctl() via the
> of (rtc) real-time clock interface. The bit pattern then determines when
> the task will run or activate next.
> 
> The /dev/rtc interface is choosen for this purpose because of its
> accessibilty to userspace. For example, the mplayer program already use
> it as a timer source and could possibly benefit from being sync to a
> vertical retrace interrupt during decoding. Could be an OpenGL program
> needing precisely scheduler support for those same handling vertical
> retrace interrupts, low latency audio and timely handling of touch
> events amognst other uses.

Sounds like you want SGI's frame rate scheduler.

	-Mike