[SRU][Xenial][PATCH] System stalls when creating device node on booting

Robert Hooker sarvatt at ubuntu.com
Tue Nov 22 10:25:54 UTC 2016


This is actually scary because it could potentially affect many
workloads, but it has almost 11 months of being upstream and no
regression bugs being bisected down to this commit as far as I can
find out. In the worse case things will work like 4.5+ kernels do and
it fixes a real problem on newer systems.

Acked-by: Robert Hooker <robert.hooker at canonical.com>

On Tue, Nov 22, 2016 at 4:48 AM, Phidias Chiang
<phidias.chiang at canonical.com> wrote:
> We've found on some Apollo Lake system stalls for around 4 seconds on
> function `wait_for_completion` when creating nodes in devtmpfs. With 70+
> nodes created it can be stalled for 5+ minutes when booting.
>
> This patch can be clean picked, and shows positive result on multiple
> Apollo Lake system. The patch is already in v4.5+ so Yakkety is not
> affected.
>
>
> Yuyang Du (1):
>   sched/fair: Fix new task's load avg removed from source CPU in
>     wake_up_new_task()
>
>  kernel/sched/fair.c | 38 ++++++++++++++++++++++++++++----------
>  1 file changed, 28 insertions(+), 10 deletions(-)
>
> --
> 2.7.3
>
>
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