linux-kernel - [PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

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Message-ID: <20241110200308.103681-1-tj@kernel.org>
Date: Sun, 10 Nov 2024 10:02:50 -1000
From: Tejun Heo <tj@...nel.org>
To: void@...ifault.com
Cc: linux-kernel@...r.kernel.org,
	kernel-team@...a.com,
	sched-ext@...a.com,
	arighi@...dia.com,
	multics69@...il.com,
	me@...tlynerdless.de,
	ggherdovich@...e.com,
	dschatzberg@...a.com,
	yougmark94@...il.com
Subject: [PATCHSET sched_ext/for-6.13] sched_ext: Rename dispatch and consume kfuncs

Hello,

[v1] -> v2: Comment and documentation updates.

In sched_ext API, a repeatedly reported pain point is the overuse of the
verb "dispatch" and confusion around "consume":

- ops.dispatch()
- scx_bpf_dispatch[_vtime]()
- scx_bpf_consume()
- scx_bpf_dispatch[_vtime]_from_dsq*()

This overloading of the term is historical. Originally, there were only
built-in DSQs and moving a task into a DSQ always dispatched it for
execution. Using the verb "dispatch" for the kfuncs to move tasks into these
DSQs made sense.

Later, user DSQs were added and scx_bpf_dispatch[_vtime]() updated to be
able to insert tasks into any DSQ. The only allowed DSQ to DSQ transfer was
from a non-local DSQ to a local DSQ and this operation was named "consume".
This was already confusing as a task could be dispatched to a user DSQ from
ops.enqueue() and then the DSQ would have to be consumed in ops.dispatch().
Later addition of scx_bpf_dispatch_from_dsq*() made the confusion even worse
as "dispatch" in this context meant moving a task to an arbitrary DSQ from a
user DSQ.

Clean up the API with the following renames:

1. scx_bpf_dispatch[_vtime]()		-> scx_bpf_dsq_insert[_vtime]()
2. scx_bpf_consume()			-> scx_bpf_dsq_move_to_local()
3. scx_bpf_dispatch[_vtime]_from_dsq*()	-> scx_bpf_dsq_move[_vtime]*()

This patchset is on top of sched_ext/for-6.13 72b85bf6a7f6 ("sched_ext:
scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context") and
contains the following patches:

 0001-sched_ext-Rename-scx_bpf_dispatch-_vtime-to-scx_bpf_.patch
 0002-sched_ext-Rename-scx_bpf_consume-to-scx_bpf_dsq_move.patch
 0003-sched_ext-Rename-scx_bpf_dispatch-_vtime-_from_dsq-s.patch

and is always available in the following git branch:

 git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-api-rename-dispatch-v2

diffstat follows. Thanks.

 Documentation/scheduler/sched-ext.rst    |   71 ++++++-------
 kernel/sched/ext.c                       |  243 +++++++++++++++++++++++++++++-----------------
 tools/sched_ext/include/scx/common.bpf.h |   18 +--
 tools/sched_ext/include/scx/compat.bpf.h |  117 +++++++++++++++++++---
 tools/sched_ext/scx_central.bpf.c        |   14 +-
 tools/sched_ext/scx_flatcg.bpf.c         |   20 ++-
 tools/sched_ext/scx_qmap.bpf.c           |   36 +++---
 tools/sched_ext/scx_simple.bpf.c         |   16 +--
 8 files changed, 348 insertions(+), 187 deletions(-)

--
tejun

[v2] http://lkml.kernel.org/r/20241109194853.580310-1-tj@kernel.org