linux-kernel - Re: [PATCH] sched: fix RLIMIT_RTTIME when PI-boosting to RT

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Date:	Mon, 9 Mar 2015 19:29:11 -0400
From:	Brian Silverman <brian@...oton-tech.com>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:	Austin Schuh <austin@...oton-tech.com>, mingo@...hat.com,
	peterz <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	rt-users <linux-rt-users@...r.kernel.org>
Subject: Re: [PATCH] sched: fix RLIMIT_RTTIME when PI-boosting to RT

On Mon, Mar 9, 2015 at 1:34 PM, Sebastian Andrzej Siewior
<bigeasy@...utronix.de> wrote:

> From what I can tell not beeing a sched guy is that the patch looks
> reasonable since the timeout gets only set to zero on enqueue_task_rt().
> Is there something special you do to trigger this?

I posted some test code with two threads and a shared PTHREAD_PRIO_INHERIT
mutex. It forces repeated priority boosting from SCHED_OTHER to SCHED_RR and
then spins for a bit while boosted. It eventually receives a SIGXCPU
on non-fixed kernels.
The SIGXCPU happens much faster with a CONFIG_PREEMPT_RT kernel, and does
happen eventually with CONFIG_PREEMPT_VOLUNTARY kernels.

>
> Sebastian

Thanks,
Brian
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