linux-kernel - [PATCH 0/2] Move uclamp to each sched

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Message-Id: <cover.1719999165.git.hongyan.xia2@arm.com>
Date: Wed,  3 Jul 2024 11:07:46 +0100
From: Hongyan Xia <hongyan.xia2@....com>
To: Tejun Heo <tj@...nel.org>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] Move uclamp to each sched_class

Hi. I only just started looking at sched_ext a couple of days ago so
feel free to correct me if sched_ext patches have different rules,
different cc's and different mailing lists than normal LKML.

This mini series delegates uclamp operations to each sched_class. The
problem with the current handling of uclamp is that it seems to be a
global thing but it conditions on sched_class->uclamp_enabled anyway, so
it is in fact already kind of sched_class-specific. So, remove
sched_class->uclamp_enabled and just let each class decide what to do.

More importantly, sched_ext no longer unconditionally follows the
existing uclamp implementation, but instead each custom scheduler
decides itself what to do. It can re-use the existing uclamp, ignore
uclamp completely, or have its own uclamp implementation.

Some simple testing with trace_printk() shows uclamp_rq_{inc,dec}() are
called successfully from a sched_ext scheduler:

	[002] d..21  1016.017441: uclamp_rq_dec: sched_ext uclamp dec
	[002] dN.21  1016.017456: uclamp_rq_inc: sched_ext uclamp inc

Hongyan Xia (2):
  sched/uclamp: Delegate uclamp to each sched_class
  sched/ext: Add BPF functions for uclamp inc and dec

 kernel/sched/core.c                      | 14 ++------------
 kernel/sched/ext.c                       | 16 ++++++++++++----
 kernel/sched/fair.c                      |  6 ++----
 kernel/sched/rt.c                        |  7 +++----
 kernel/sched/sched.h                     | 15 +++++++++++----
 tools/sched_ext/include/scx/common.bpf.h |  2 ++
 6 files changed, 32 insertions(+), 28 deletions(-)

-- 
2.34.1