[RFC PATCH v3 0/3] sched: Skip queued wakeups only when L2 is shared

[Mathieu Desnoyers]

This series improves performance of scheduler wakeups on large systems
by skipping queued wakeups only when CPUs share their L2 cache, rather
than when they share their LLC.

The speedup mainly reproduces on workloads which have at least *some*
idle time (because it significantly increases the number of migrations,
and thus remote wakeups), *and* it needs to have a sufficient load to
cause contention on the runqueue locks.

Feedback is welcome,

Thanks,

Mathieu

Mathieu Desnoyers (3):
  sched: Rename cpus_share_cache to cpus_share_llc
  sched: Introduce cpus_share_l2c (v3)
  sched: ttwu_queue_cond: skip queued wakeups across different l2 caches

Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ben Segall <bsegall@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Swapnil Sapkal <Swapnil.Sapkal@xxxxxxx>
Cc: Aaron Lu <aaron.lu@xxxxxxxxx>
Cc: Julien Desfossez <jdesfossez@xxxxxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx

 block/blk-mq.c                 |  2 +-
 include/linux/sched/topology.h | 10 ++++++++--
 kernel/sched/core.c            | 14 +++++++++++---
 kernel/sched/fair.c            |  8 ++++----
 kernel/sched/sched.h           |  2 ++
 kernel/sched/topology.c        | 32 +++++++++++++++++++++++++++++---
 6 files changed, 55 insertions(+), 13 deletions(-)

-- 
2.39.2