sched/eevdf: Rate limit task migration

Implement task migration rate limiting to speed up workload patterns
such as hackbench which trigger frequent migrations.

The first patch implements a simple rate limiting of 1 migration per
2ms. The second patch implements adaptative task migration rate
limiting.

I would be interested to hear feedback on this approach, especially
about how it behaves on various workloads.

Thanks,

Mathieu

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Swapnil Sapkal <Swapnil.Sapkal@amd.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Julien Desfossez <jdesfossez@digitalocean.com>
Cc: x86@kernel.org

Mathieu Desnoyers (2):
  sched: rate limit migrations to 1 per 2ms per task
  sched: Implement adaptative rate limiting of task migrations

 include/linux/sched.h |  4 ++++
 kernel/sched/core.c   |  3 +++
 kernel/sched/fair.c   | 40 ++++++++++++++++++++++++++++++++++++++++
 kernel/sched/sched.h  |  4 ++++
 4 files changed, 51 insertions(+)

-- 
2.39.2