When LRUs are pending, the drain can be triggered remotely, whether the
remote CPU is running in userspace in nohz_full mode or not. This kind
of noise is expected to be caused by preparatory work before a task
runs isolated in userspace. This patchset is a proposal to flush that
before the task starts its critical work in userspace.
Changes since v1:
_ Various task_work improvements (Oleg)
_ Remove leftover comment on numa_work (Valentin)
_ Add Reviewed-by tag from Valentin
_ Use housekeeping_cpu() instead of housekeeping_test_cpu() on
fastpath to benefit from static branch (Vlastimil)
_ Spare the actual remote LRU drain when the target CPU is nohz_full. It
is assumed the LRU drain will happen locally eventually. (Michal)
Frederic Weisbecker (6):
task_work: Provide means to check if a work is queued
sched/fair: Use task_work_queued() on numa_work
sched: Use task_work_queued() on cid_work
tick/nohz: Move nohz_full related fields out of hot task struct's
places
sched/isolation: Introduce isolated task work
mm: Drain LRUs upon resume to userspace on nohz_full CPUs
include/linux/sched.h | 15 +++++++++------
include/linux/sched/isolation.h | 17 +++++++++++++++++
include/linux/swap.h | 1 +
include/linux/task_work.h | 12 ++++++++++++
kernel/sched/core.c | 6 ++----
kernel/sched/fair.c | 5 +----
kernel/sched/isolation.c | 34 +++++++++++++++++++++++++++++++++
kernel/sched/sched.h | 1 +
kernel/task_work.c | 11 +++++++++--
mm/swap.c | 8 +++++++-
10 files changed, 93 insertions(+), 17 deletions(-)
--
2.46.0
