* [PATCH v3 1/2] sched_ext: Update demo schedulers and selftests to use scx_bpf_task_set_dsq_vtime()
2026-03-13 1:49 [PATCH v3 0/2] sched_ext: Update demo schedulers and selftests for deprecated APIs Cheng-Yang Chou
@ 2026-03-13 1:49 ` Cheng-Yang Chou
2026-03-13 16:56 ` Tejun Heo
2026-03-13 1:49 ` [PATCH v3 2/2] sched_ext: Update demo schedulers and selftests to drop ops.cpu_acquire/release() Cheng-Yang Chou
1 sibling, 1 reply; 5+ messages in thread
From: Cheng-Yang Chou @ 2026-03-13 1:49 UTC (permalink / raw)
To: sched-ext; +Cc: tj, void, arighi, changwoo, jserv, yphbchou0911
Direct writes to p->scx.dsq_vtime are deprecated in favor of
scx_bpf_task_set_dsq_vtime(). Update scx_simple, scx_flatcg, and
select_cpu_vtime selftest to use the new kfunc with
scale_by_task_weight_inverse().
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
---
tools/sched_ext/scx_flatcg.bpf.c | 9 +++++----
tools/sched_ext/scx_simple.bpf.c | 6 ++++--
tools/testing/selftests/sched_ext/select_cpu_vtime.bpf.c | 7 +++++--
3 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
index a8a9234bb41e..c734ef616c7f 100644
--- a/tools/sched_ext/scx_flatcg.bpf.c
+++ b/tools/sched_ext/scx_flatcg.bpf.c
@@ -551,9 +551,10 @@ void BPF_STRUCT_OPS(fcg_stopping, struct task_struct *p, bool runnable)
* too much, determine the execution time by taking explicit timestamps
* instead of depending on @p->scx.slice.
*/
+ u64 delta = scale_by_task_weight_inverse(p, SCX_SLICE_DFL - p->scx.slice);
+
if (!fifo_sched)
- p->scx.dsq_vtime +=
- (SCX_SLICE_DFL - p->scx.slice) * 100 / p->scx.weight;
+ scx_bpf_task_set_dsq_vtime(p, p->scx.dsq_vtime + delta);
taskc = bpf_task_storage_get(&task_ctx, p, 0, 0);
if (!taskc) {
@@ -822,7 +823,7 @@ s32 BPF_STRUCT_OPS(fcg_init_task, struct task_struct *p,
if (!(cgc = find_cgrp_ctx(args->cgroup)))
return -ENOENT;
- p->scx.dsq_vtime = cgc->tvtime_now;
+ scx_bpf_task_set_dsq_vtime(p, cgc->tvtime_now);
return 0;
}
@@ -924,7 +925,7 @@ void BPF_STRUCT_OPS(fcg_cgroup_move, struct task_struct *p,
return;
delta = time_delta(p->scx.dsq_vtime, from_cgc->tvtime_now);
- p->scx.dsq_vtime = to_cgc->tvtime_now + delta;
+ scx_bpf_task_set_dsq_vtime(p, to_cgc->tvtime_now + delta);
}
s32 BPF_STRUCT_OPS_SLEEPABLE(fcg_init)
diff --git a/tools/sched_ext/scx_simple.bpf.c b/tools/sched_ext/scx_simple.bpf.c
index b456bd7cae77..024c3ce29610 100644
--- a/tools/sched_ext/scx_simple.bpf.c
+++ b/tools/sched_ext/scx_simple.bpf.c
@@ -121,12 +121,14 @@ void BPF_STRUCT_OPS(simple_stopping, struct task_struct *p, bool runnable)
* too much, determine the execution time by taking explicit timestamps
* instead of depending on @p->scx.slice.
*/
- p->scx.dsq_vtime += (SCX_SLICE_DFL - p->scx.slice) * 100 / p->scx.weight;
+ u64 delta = scale_by_task_weight_inverse(p, SCX_SLICE_DFL - p->scx.slice);
+
+ scx_bpf_task_set_dsq_vtime(p, p->scx.dsq_vtime + delta);
}
void BPF_STRUCT_OPS(simple_enable, struct task_struct *p)
{
- p->scx.dsq_vtime = vtime_now;
+ scx_bpf_task_set_dsq_vtime(p, vtime_now);
}
s32 BPF_STRUCT_OPS_SLEEPABLE(simple_init)
diff --git a/tools/testing/selftests/sched_ext/select_cpu_vtime.bpf.c b/tools/testing/selftests/sched_ext/select_cpu_vtime.bpf.c
index bfcb96cd4954..a2c6be98b81b 100644
--- a/tools/testing/selftests/sched_ext/select_cpu_vtime.bpf.c
+++ b/tools/testing/selftests/sched_ext/select_cpu_vtime.bpf.c
@@ -66,12 +66,15 @@ void BPF_STRUCT_OPS(select_cpu_vtime_running, struct task_struct *p)
void BPF_STRUCT_OPS(select_cpu_vtime_stopping, struct task_struct *p,
bool runnable)
{
- p->scx.dsq_vtime += (SCX_SLICE_DFL - p->scx.slice) * 100 / p->scx.weight;
+ u64 delta = scale_by_task_weight_inverse(p, SCX_SLICE_DFL - p->scx.slice);
+
+ scx_bpf_task_set_dsq_vtime(p, p->scx.dsq_vtime + delta);
+
}
void BPF_STRUCT_OPS(select_cpu_vtime_enable, struct task_struct *p)
{
- p->scx.dsq_vtime = vtime_now;
+ scx_bpf_task_set_dsq_vtime(p, vtime_now);
}
s32 BPF_STRUCT_OPS_SLEEPABLE(select_cpu_vtime_init)
--
2.48.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v3 2/2] sched_ext: Update demo schedulers and selftests to drop ops.cpu_acquire/release()
2026-03-13 1:49 [PATCH v3 0/2] sched_ext: Update demo schedulers and selftests for deprecated APIs Cheng-Yang Chou
2026-03-13 1:49 ` [PATCH v3 1/2] sched_ext: Update demo schedulers and selftests to use scx_bpf_task_set_dsq_vtime() Cheng-Yang Chou
@ 2026-03-13 1:49 ` Cheng-Yang Chou
1 sibling, 0 replies; 5+ messages in thread
From: Cheng-Yang Chou @ 2026-03-13 1:49 UTC (permalink / raw)
To: sched-ext; +Cc: tj, void, arighi, changwoo, jserv, yphbchou0911
ops.cpu_acquire/release() are deprecated by commit a3f5d4822253
("sched_ext: Allow scx_bpf_reenqueue_local() to be called from
anywhere") in favor of handling CPU preemption via the sched_switch
tracepoint. Update scx_qmap and the maximal selftest to use the new
approach.
In scx_qmap, remove the cpu_release fallback and the
__COMPAT_scx_bpf_reenqueue_local_from_anywhere() compat guard from
qmap_sched_switch(), unconditionally handling preemption via the TP.
In the maximal selftest, replace the cpu_acquire/release stubs with a
minimal sched_switch TP program. Attach all non-struct_ops programs
(including the new TP) via maximal__attach() after disabling auto-attach
for the maximal_ops struct_ops map, which is managed manually in run().
Apply the same fix to reload_loop, which also uses the maximal skeleton.
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
---
tools/sched_ext/scx_qmap.bpf.c | 15 ++-------------
tools/testing/selftests/sched_ext/maximal.bpf.c | 15 ++++++---------
tools/testing/selftests/sched_ext/maximal.c | 3 +++
tools/testing/selftests/sched_ext/reload_loop.c | 3 +++
4 files changed, 14 insertions(+), 22 deletions(-)
diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c
index a4a1b84fe359..a11e27c8de77 100644
--- a/tools/sched_ext/scx_qmap.bpf.c
+++ b/tools/sched_ext/scx_qmap.bpf.c
@@ -11,8 +11,8 @@
*
* - BPF-side queueing using PIDs.
* - Sleepable per-task storage allocation using ops.prep_enable().
- * - Using ops.cpu_release() to handle a higher priority scheduling class taking
- * the CPU away.
+ * - Using the sched_switch tracepoint to handle a higher priority scheduling
+ * class taking the CPU away.
* - Core-sched support.
*
* This scheduler is primarily for demonstration and testing of sched_ext
@@ -562,9 +562,6 @@ SEC("tp_btf/sched_switch")
int BPF_PROG(qmap_sched_switch, bool preempt, struct task_struct *prev,
struct task_struct *next, unsigned long prev_state)
{
- if (!__COMPAT_scx_bpf_reenqueue_local_from_anywhere())
- return 0;
-
/*
* If @cpu is taken by a higher priority scheduling class, it is no
* longer available for executing sched_ext tasks. As we don't want the
@@ -586,13 +583,6 @@ int BPF_PROG(qmap_sched_switch, bool preempt, struct task_struct *prev,
return 0;
}
-void BPF_STRUCT_OPS(qmap_cpu_release, s32 cpu, struct scx_cpu_release_args *args)
-{
- /* see qmap_sched_switch() to learn how to do this on newer kernels */
- if (!__COMPAT_scx_bpf_reenqueue_local_from_anywhere())
- scx_bpf_reenqueue_local();
-}
-
s32 BPF_STRUCT_OPS(qmap_init_task, struct task_struct *p,
struct scx_init_task_args *args)
{
@@ -999,7 +989,6 @@ SCX_OPS_DEFINE(qmap_ops,
.dispatch = (void *)qmap_dispatch,
.tick = (void *)qmap_tick,
.core_sched_before = (void *)qmap_core_sched_before,
- .cpu_release = (void *)qmap_cpu_release,
.init_task = (void *)qmap_init_task,
.dump = (void *)qmap_dump,
.dump_cpu = (void *)qmap_dump_cpu,
diff --git a/tools/testing/selftests/sched_ext/maximal.bpf.c b/tools/testing/selftests/sched_ext/maximal.bpf.c
index 01cf4f3da4e0..5858f64313e9 100644
--- a/tools/testing/selftests/sched_ext/maximal.bpf.c
+++ b/tools/testing/selftests/sched_ext/maximal.bpf.c
@@ -67,13 +67,12 @@ void BPF_STRUCT_OPS(maximal_set_cpumask, struct task_struct *p,
void BPF_STRUCT_OPS(maximal_update_idle, s32 cpu, bool idle)
{}
-void BPF_STRUCT_OPS(maximal_cpu_acquire, s32 cpu,
- struct scx_cpu_acquire_args *args)
-{}
-
-void BPF_STRUCT_OPS(maximal_cpu_release, s32 cpu,
- struct scx_cpu_release_args *args)
-{}
+SEC("tp_btf/sched_switch")
+int BPF_PROG(maximal_sched_switch, bool preempt, struct task_struct *prev,
+ struct task_struct *next, unsigned long prev_state)
+{
+ return 0;
+}
void BPF_STRUCT_OPS(maximal_cpu_online, s32 cpu)
{}
@@ -150,8 +149,6 @@ struct sched_ext_ops maximal_ops = {
.set_weight = (void *) maximal_set_weight,
.set_cpumask = (void *) maximal_set_cpumask,
.update_idle = (void *) maximal_update_idle,
- .cpu_acquire = (void *) maximal_cpu_acquire,
- .cpu_release = (void *) maximal_cpu_release,
.cpu_online = (void *) maximal_cpu_online,
.cpu_offline = (void *) maximal_cpu_offline,
.init_task = (void *) maximal_init_task,
diff --git a/tools/testing/selftests/sched_ext/maximal.c b/tools/testing/selftests/sched_ext/maximal.c
index c6be50a9941d..1dc369224670 100644
--- a/tools/testing/selftests/sched_ext/maximal.c
+++ b/tools/testing/selftests/sched_ext/maximal.c
@@ -19,6 +19,9 @@ static enum scx_test_status setup(void **ctx)
SCX_ENUM_INIT(skel);
SCX_FAIL_IF(maximal__load(skel), "Failed to load skel");
+ bpf_map__set_autoattach(skel->maps.maximal_ops, false);
+ SCX_FAIL_IF(maximal__attach(skel), "Failed to attach skel");
+
*ctx = skel;
return SCX_TEST_PASS;
diff --git a/tools/testing/selftests/sched_ext/reload_loop.c b/tools/testing/selftests/sched_ext/reload_loop.c
index 308211d80436..49297b83d748 100644
--- a/tools/testing/selftests/sched_ext/reload_loop.c
+++ b/tools/testing/selftests/sched_ext/reload_loop.c
@@ -23,6 +23,9 @@ static enum scx_test_status setup(void **ctx)
SCX_ENUM_INIT(skel);
SCX_FAIL_IF(maximal__load(skel), "Failed to load skel");
+ bpf_map__set_autoattach(skel->maps.maximal_ops, false);
+ SCX_FAIL_IF(maximal__attach(skel), "Failed to attach skel");
+
return SCX_TEST_PASS;
}
--
2.48.1
^ permalink raw reply related [flat|nested] 5+ messages in thread