linux-kernel - Re: [RFC 4/8] Improve the tracking of active utilisation

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Message-ID: <20160128121441.0ebde65d@utopia>
Date:	Thu, 28 Jan 2016 12:14:41 +0100
From:	luca abeni <luca.abeni@...tn.it>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	Juri Lelli <juri.lelli@....com>
Subject: Re: [RFC 4/8] Improve the tracking of active utilisation

Hi Peter,

On Wed, 27 Jan 2016 15:39:46 +0100
Peter Zijlstra <peterz@...radead.org> wrote:

> On Wed, Jan 27, 2016 at 02:36:51PM +0100, Luca Abeni wrote:
> > Ok, so I implemented this idea, and I am currently testing it...
> > The first experiments seem to show that there are no problems, but I
> > just tried some simple workload (rt-app, or some other periodic
> > taskset scheduled by SCHED_DEADLINE). Do you have suggestions for
> > more "interesting" (and meaningful) tests/experiments?
> 
> rt-app is the workload generator, right?
> 
> I think the most interesting part here is the switched_from path, so
> you'd want the workload to include a !rt task that gets PI boosted to
> deadline every so often.
I am looking at the PI stuff right now... And I am not sure if
SCHED_DEADLINE does the right thing for PI :)

Anyway, I think the total SCHED_DEADLINE utilization (rd->dl_bw) is
currently not changed when a SCHED_OTHER task is boosted to
SCHED_DEADLINE due to PI... Right? Is this the desired behaviour?
If yes, I'll make sure that my patch does not change it.



			Thanks,
				Luca