linux-kernel - [RFC][PATCH 00/16] sched: Core scheduling

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Message-Id: <20190218165620.383905466@infradead.org>
Date:   Mon, 18 Feb 2019 17:56:20 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     mingo@...nel.org, tglx@...utronix.de, pjt@...gle.com,
        tim.c.chen@...ux.intel.com, torvalds@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, subhra.mazumdar@...cle.com,
        fweisbec@...il.com, keescook@...omium.org, kerrnel@...gle.com,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [RFC][PATCH 00/16] sched: Core scheduling

A much 'demanded' feature: core-scheduling :-(

I still hate it with a passion, and that is part of why it took a little
longer than 'promised'.

While this one doesn't have all the 'features' of the previous (never
published) version and isn't L1TF 'complete', I tend to like the structure
better (relatively speaking: I hate it slightly less).

This one is sched class agnostic and therefore, in principle, doesn't horribly
wreck RT (in fact, RT could 'ab'use this by setting 'task->core_cookie = task'
to force-idle siblings).

Now, as hinted by that, there are semi sane reasons for actually having this.
Various hardware features like Intel RDT - Memory Bandwidth Allocation, work
per core (due to SMT fundamentally sharing caches) and therefore grouping
related tasks on a core makes it more reliable.

However; whichever way around you turn this cookie; it is expensive and nasty.

It doesn't help that there are truly bonghit crazy proposals for using this out
there, and I really hope to never see them in code.

These patches are lightly tested and didn't insta explode, but no promises,
they might just set your pets on fire.

'enjoy'

@pjt; I know this isn't quite what we talked about, but this is where I ended
up after I started typing. There's plenty design decisions to question and my
changelogs don't even get close to beginning to cover them all. Feel free to ask.

---
 include/linux/sched.h    |   9 +-
 kernel/Kconfig.preempt   |   8 +-
 kernel/sched/core.c      | 762 ++++++++++++++++++++++++++++++++++++++++++++---
 kernel/sched/deadline.c  |  99 +++---
 kernel/sched/debug.c     |   4 +-
 kernel/sched/fair.c      | 129 +++++---
 kernel/sched/idle.c      |  42 ++-
 kernel/sched/pelt.h      |   2 +-
 kernel/sched/rt.c        |  96 +++---
 kernel/sched/sched.h     | 183 ++++++++----
 kernel/sched/stop_task.c |  35 ++-
 kernel/sched/topology.c  |   4 +-
 kernel/stop_machine.c    |   2 +
 13 files changed, 1096 insertions(+), 279 deletions(-)