[RFC PATCH 0/6] mm: LRU drain flush on nohz_full

From: Frederic Weisbecker
Date: Tue Jun 25 2024 - 09:52:59 EST


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.

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 | 4 +---
kernel/sched/isolation.c | 32 ++++++++++++++++++++++++++++++++
kernel/sched/sched.h | 1 +
kernel/task_work.c | 1 +
mm/swap.c | 5 ++++-
10 files changed, 80 insertions(+), 14 deletions(-)

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2.45.2