Re: [RFC PATCH 3/6] sched/dl: Try better placement even for deadline tasks that do not block

From: Juri Lelli
Date: Wed May 08 2019 - 04:02:20 EST

Hi Luca,

On 06/05/19 06:48, Luca Abeni wrote:
> From: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>
> Currently, the scheduler tries to find a proper placement for
> SCHED_DEADLINE tasks when they are pushed out of a core or when
> they wake up. Hence, if there is a single SCHED_DEADLINE task
> that never blocks and wakes up, such a task is never migrated to
> an appropriate CPU core, but continues to execute on its original
> core.
> This commit addresses the issue by trying to migrate a SCHED_DEADLINE
> task (searching for an appropriate CPU core) the first time it is
> throttled.

Why we failed to put the task on a CPU with enough (max) capacity right
after it passed admission control? The very first time the task was
scheduled I mean.


- Juri