linux-kernel - [PATCH 0/9] sched: Migrate disable support

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Message-ID: <20200921163557.234036895@infradead.org>
Date:   Mon, 21 Sep 2020 18:35:57 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     tglx@...utronix.de, mingo@...nel.org
Cc:     linux-kernel@...r.kernel.org, bigeasy@...utronix.de,
        qais.yousef@....com, swood@...hat.com, peterz@...radead.org,
        valentin.schneider@....com, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vincent.donnefort@....com
Subject: [PATCH 0/9] sched: Migrate disable support

Hi,

Here's my take on migrate_disable(). It avoids growing a second means of
changing the affinity, documents how the things violates locking rules but
still mostly works.

It also avoids blocking completely, so no more futex band-aids required.

Also, no more atomics/locks on the fast path.

I also put in a comment that explains how the whole concept is fundamentally
flawed but a necessary evil to get PREEMPT_RT going -- for now.

Somewhat tested with PREEMPT_RT.

---
 include/linux/cpuhotplug.h    |    1 
 include/linux/preempt.h       |   60 +++
 include/linux/sched.h         |    4 
 include/linux/sched/hotplug.h |    2 
 include/linux/stop_machine.h  |    5 
 kernel/cpu.c                  |    9 
 kernel/sched/core.c           |  673 +++++++++++++++++++++++++++++++-----------
 kernel/sched/deadline.c       |    5 
 kernel/sched/sched.h          |   24 +
 kernel/stop_machine.c         |   23 +
 lib/dump_stack.c              |    2 
 lib/smp_processor_id.c        |    5 
 12 files changed, 635 insertions(+), 178 deletions(-)