linux-kernel - Re: [BUG] Corrupted SCHED_DEADLINE bandwidth with cpusets

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Message-ID: <20160203135755.07f59bc2@gandalf.local.home>
Date:	Wed, 3 Feb 2016 13:57:55 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Clark Williams <williams@...hat.com>,
	John Kacur <jkacur@...hat.com>,
	Daniel Bristot de Oliveira <bristot@...hat.com>,
	Juri Lelli <juri.lelli@...il.com>
Subject: Re: [BUG] Corrupted SCHED_DEADLINE bandwidth with cpusets

On Wed, 3 Feb 2016 13:55:50 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

>  # grep dl /proc/sched_debug
> dl_rq[0]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : -104857
> dl_rq[1]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : -104857
> dl_rq[2]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : -104857
> dl_rq[3]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : -104857
> dl_rq[4]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : -104857
> dl_rq[5]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : -104857
> dl_rq[6]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : -104857
> dl_rq[7]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : -104857
> 
> They all went negative!
> 
> Not good, but we can recover...

Even though we can recover, I'm betting we can easily overcommit
deadline tasks here. It probably wouldn't be too hard to come up with a
test case that does so.

-- Steve