linux.git/kernel/sched/ext.h, branch v6.18.22

sched_ext: Use cgroup_lock/unlock() to synchronize against cgroup operations

2025-09-03T21:36:07+00:00

SCX hooks into CPU cgroup controller operations and read-locks
scx_cgroup_rwsem to exclude them while enabling and disable schedulers.
While this works, it's unnecessarily complicated given that
cgroup_[un]lock() are available and thus the cgroup operations can be locked
out that way.

Drop scx_cgroup_rwsem locking from the tg on/offline and cgroup [can_]attach
operations. Instead, grab cgroup_lock() from scx_cgroup_lock(). Drop
scx_cgroup_finish_attach() which is no longer necessary. Drop the now
unnecessary rcu locking and css ref bumping in scx_cgroup_init() and
scx_cgroup_exit().

As scx_cgroup_set_weight/bandwidth() paths aren't protected by
cgroup_lock(), rename scx_cgroup_rwsem to scx_cgroup_ops_rwsem and retain
the locking there.

This is overall simpler and will also allow enable/disable paths to
synchronize against cgroup changes independent of the CPU controller.

Signed-off-by: Tejun Heo 
Cc: Peter Zijlstra 
Acked-by: Andrea Righi

sched_ext: Move internal type and accessor definitions to ext_internal.h

2025-09-03T21:33:28+00:00

There currently isn't a place to place SCX-internal types and accessors to
be shared between ext.c and ext_idle.c. Create kernel/sched/ext_internal.h
and move internal type and accessor definitions there. This trims ext.c a
bit and makes future additions easier. Pure code reorganization. No
functional changes.

Signed-off-by: Tejun Heo 
Acked-by: Andrea Righi

sched_ext: Add support for cgroup bandwidth control interface

2025-06-21T03:03:51+00:00

From 077814f57f8acce13f91dc34bbd2b7e4911fbf25 Mon Sep 17 00:00:00 2001
From: Tejun Heo 
Date: Fri, 13 Jun 2025 15:06:47 -1000

- Add CONFIG_GROUP_SCHED_BANDWIDTH which is selected by both
  CONFIG_CFS_BANDWIDTH and EXT_GROUP_SCHED.

- Put bandwidth control interface files for both cgroup v1 and v2 under
  CONFIG_GROUP_SCHED_BANDWIDTH.

- Update tg_bandwidth() to fetch configuration parameters from fair if
  CONFIG_CFS_BANDWIDTH, SCX otherwise.

- Update tg_set_bandwidth() to update the parameters for both fair and SCX.

- Add bandwidth control parameters to struct scx_cgroup_init_args.

- Add sched_ext_ops.cgroup_set_bandwidth() which is invoked on bandwidth
  control parameter updates.

- Update scx_qmap and maximal selftest to test the new feature.

Signed-off-by: Tejun Heo

sched_ext: Merge branch 'for-6.16-fixes' into for-6.17

2025-06-21T03:01:21+00:00

Pull sched_ext/for-6.16-fixes to receive:

 c50784e99f0e ("sched_ext: Make scx_group_set_weight() always update tg->scx.weight")
 33796b91871a ("sched_ext, sched/core: Don't call scx_group_set_weight() prematurely from sched_create_group()")

which are needed to implement CPU bandwidth control interface support.

Signed-off-by: Tejun Heo

sched_ext, sched/core: Don't call scx_group_set_weight() prematurely from sched_create_group()

2025-06-17T18:19:55+00:00

During task_group creation, sched_create_group() calls
scx_group_set_weight() with CGROUP_WEIGHT_DFL to initialize the sched_ext
portion. This is premature and ends up calling ops.cgroup_set_weight() with
an incorrect @cgrp before ops.cgroup_init() is called.

sched_create_group() should just initialize SCX related fields in the new
task_group. Fix it by factoring out scx_tg_init() from sched_init() and
making sched_create_group() call that function instead of
scx_group_set_weight().

v2: Retain CONFIG_EXT_GROUP_SCHED ifdef in sched_init() as removing it leads
    to build failures on !CONFIG_GROUP_SCHED configs.

Signed-off-by: Tejun Heo 
Fixes: 819513666966 ("sched_ext: Add cgroup support")
Cc: stable@vger.kernel.org # v6.12+

sched_ext: Always use SMP versions in kernel/sched/ext.h

2025-06-14T00:30:58+00:00

Simplify the scheduler by making formerly SMP-only primitives and data
structures unconditional.

tj: Updated subject for clarity. Replace #if defined() with #ifdef.

Signed-off-by: Cheng-Yang Chou 
Signed-off-by: Tejun Heo

sched_ext: Make scx_locked_rq() inline

2025-06-09T16:25:35+00:00

scx_locked_rq() is used both from ext.c and ext_idle.c, move it to ext.h
as a static inline function.

No functional changes.

v2: Rename locked_rq to scx_locked_rq_state, expose it and make
    scx_locked_rq() inline, as suggested by Tejun.

Signed-off-by: Andrea Righi 
Signed-off-by: Tejun Heo

sched_ext: Make scx_rq_bypassing() inline

2025-06-09T16:25:24+00:00

scx_rq_bypassing() is used both from ext.c and ext_idle.c, move it to
ext.h as a static inline function.

No functional changes.

Signed-off-by: Andrea Righi 
Signed-off-by: Tejun Heo

sched_ext: Make scx_kf_allowed_if_unlocked() available outside ext.c

2025-05-20T20:23:50+00:00

Relocate the scx_kf_allowed_if_unlocked(), so it can be used from other
source files (e.g., ext_idle.c).

No functional change.

Signed-off-by: Andrea Righi 
Signed-off-by: Tejun Heo

sched_ext: Remove scx_ops_allow_queued_wakeup static_key

2025-04-09T19:06:00+00:00

scx_ops_allow_queued_wakeup is used to encode SCX_OPS_ALLOW_QUEUED_WAKEUP
into a static_key. The test is gated behind scx_enabled(), and, even when
sched_ext is enabled, is unlikely for the static_key usage to make any
meaningful difference. It is made to use a static_key mostly because there
was no reason not to. However, global static_keys can't work with the
planned hierarchical multiple scheduler support. Remove the static_key and
instead test SCX_OPS_ALLOW_QUEUED_WAKEUP directly.

In repeated hackbench runs before and after static_keys removal on an AMD
Ryzen 3900X, I couldn't tell any measurable performance difference.

Signed-off-by: Tejun Heo 
Acked-by: Changwoo Min 
Acked-by: Andrea Righi