Re: [BUG] Corrupted SCHED_DEADLINE bandwidth with cpusets

[Juri Lelli]

On 04/02/16 12:31, Steven Rostedt wrote:
> On Thu, 4 Feb 2016 16:30:49 +0000
> Juri Lelli <juri.lelli@xxxxxxx> wrote:
> 
> > I've actually changed a bit this approach, and things seem better here.
> > Could you please give this a try? (You can also fetch the same branch).
> 
> It appears to fix the one issue I pointed out, but it doesn't fix the
> issue with cpusets.
> 
>  # burn&
>  # TASK=$!
>  # schedtool -E -t 2000000:20000000 $TASK
>  # 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
> 
>  # mkdir /sys/fs/cgroup/cpuset/my_cpuset
>  # echo 1 > /sys/fs/cgroup/cpuset/my_cpuset/cpuset.cpus
>  # grep dl /proc/sched_debug
> dl_rq[0]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : 209714
> dl_rq[1]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : 209714
> dl_rq[2]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : 209714
> dl_rq[3]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : 209714
> dl_rq[4]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : 209714
> dl_rq[5]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : 209714
> dl_rq[6]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : 209714
> dl_rq[7]:
>   .dl_nr_running                 : 0
>   .dl_bw->bw                     : 996147
>   .dl_bw->total_bw               : 209714
> 
> It appears to add double the bandwidth.
> 

Mmm.. IIUC that's because we don't destroy any root_domain in this case,
as sched_load_balance of the parent is still set. So we add again to the
existing one. I could fix that with some flag indicating when we
actually destroy root_domain(s), but I fear it will make this solution
uglier than it is already :/. More thinking required.

Thanks for testing.

Best,

- Juri