Merge tag 'sched_ext-for-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

Pull sched_ext updates from Tejun Heo:

 - scx_bpf_now() added so that BPF scheduler can access the cached
   timestamp in struct rq to avoid reading TSC multiple times within a
   locked scheduling operation.

 - Minor updates to the built-in idle CPU selection logic.

 - tool/sched_ext updates and other misc changes.

* tag 'sched_ext-for-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
  sched_ext: fix kernel-doc warnings
  sched_ext: Use time helpers in BPF schedulers
  sched_ext: Replace bpf_ktime_get_ns() to scx_bpf_now()
  sched_ext: Add time helpers for BPF schedulers
  sched_ext: Add scx_bpf_now() for BPF scheduler
  sched_ext: Implement scx_bpf_now()
  sched_ext: Relocate scx_enabled() related code
  sched_ext: Add option -l in selftest runner to list all available tests
  sched_ext: Include remaining task time slice in error state dump
  sched_ext: update scx_bpf_dsq_insert() doc for SCX_DSQ_LOCAL_ON
  sched_ext: idle: small CPU iteration refactoring
  sched_ext: idle: introduce check_builtin_idle_enabled() helper
  sched_ext: idle: clarify comments
  sched_ext: idle: use assign_cpu() to update the idle cpumask
  sched_ext: Use str_enabled_disabled() helper in update_selcpu_topology()
  sched_ext: Use sizeof_field for key_len in dsq_hash_params
  tools/sched_ext: Receive updates from SCX repo
  sched_ext: Use the NUMA scheduling domain for NUMA optimizations

21 files changed, 690 insertions, 160 deletions

diff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst
index 6d83df3dd74e..c4672d7df2f7 100644
--- a/Documentation/scheduler/sched-ext.rst
+++ b/Documentation/scheduler/sched-ext.rst
@@ -242,9 +242,9 @@ The following briefly shows how a waking task is scheduled and executed.
    task was inserted directly from ``ops.select_cpu()``). ``ops.enqueue()``
    can make one of the following decisions:
 
-   * Immediately insert the task into either the global or local DSQ by
-     calling ``scx_bpf_dsq_insert()`` with ``SCX_DSQ_GLOBAL`` or
-     ``SCX_DSQ_LOCAL``, respectively.
+   * Immediately insert the task into either the global or a local DSQ by
+     calling ``scx_bpf_dsq_insert()`` with one of the following options:
+     ``SCX_DSQ_GLOBAL``, ``SCX_DSQ_LOCAL``, or ``SCX_DSQ_LOCAL_ON | cpu``.
 
    * Immediately insert the task into a custom DSQ by calling
      ``scx_bpf_dsq_insert()`` with a DSQ ID which is smaller than 2^63.
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 88a9a515b2ba..901170708e2a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -793,6 +793,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
 void update_rq_clock(struct rq *rq)
 {
 	s64 delta;
+	u64 clock;
 
 	lockdep_assert_rq_held(rq);
 
@@ -804,11 +805,14 @@ void update_rq_clock(struct rq *rq)
 		SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);
 	rq->clock_update_flags |= RQCF_UPDATED;
 #endif
+	clock = sched_clock_cpu(cpu_of(rq));
+	scx_rq_clock_update(rq, clock);
 
-	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
+	delta = clock - rq->clock;
 	if (delta < 0)
 		return;
 	rq->clock += delta;
+
 	update_rq_clock_task(rq, delta);
 }
 
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 7fee43426ee7..8857c0709bdd 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -206,7 +206,7 @@ struct scx_dump_ctx {
  */
 struct sched_ext_ops {
 	/**
-	 * select_cpu - Pick the target CPU for a task which is being woken up
+	 * @select_cpu: Pick the target CPU for a task which is being woken up
 	 * @p: task being woken up
 	 * @prev_cpu: the cpu @p was on before sleeping
 	 * @wake_flags: SCX_WAKE_*
@@ -233,7 +233,7 @@ struct sched_ext_ops {
 	s32 (*select_cpu)(struct task_struct *p, s32 prev_cpu, u64 wake_flags);
 
 	/**
-	 * enqueue - Enqueue a task on the BPF scheduler
+	 * @enqueue: Enqueue a task on the BPF scheduler
 	 * @p: task being enqueued
 	 * @enq_flags: %SCX_ENQ_*
 	 *
@@ -248,7 +248,7 @@ struct sched_ext_ops {
 	void (*enqueue)(struct task_struct *p, u64 enq_flags);
 
 	/**
-	 * dequeue - Remove a task from the BPF scheduler
+	 * @dequeue: Remove a task from the BPF scheduler
 	 * @p: task being dequeued
 	 * @deq_flags: %SCX_DEQ_*
 	 *
@@ -264,7 +264,7 @@ struct sched_ext_ops {
 	void (*dequeue)(struct task_struct *p, u64 deq_flags);
 
 	/**
-	 * dispatch - Dispatch tasks from the BPF scheduler and/or user DSQs
+	 * @dispatch: Dispatch tasks from the BPF scheduler and/or user DSQs
 	 * @cpu: CPU to dispatch tasks for
 	 * @prev: previous task being switched out
 	 *
@@ -287,7 +287,7 @@ struct sched_ext_ops {
 	void (*dispatch)(s32 cpu, struct task_struct *prev);
 
 	/**
-	 * tick - Periodic tick
+	 * @tick: Periodic tick
 	 * @p: task running currently
 	 *
 	 * This operation is called every 1/HZ seconds on CPUs which are
@@ -297,7 +297,7 @@ struct sched_ext_ops {
 	void (*tick)(struct task_struct *p);
 
 	/**
-	 * runnable - A task is becoming runnable on its associated CPU
+	 * @runnable: A task is becoming runnable on its associated CPU
 	 * @p: task becoming runnable
 	 * @enq_flags: %SCX_ENQ_*
 	 *
@@ -324,7 +324,7 @@ struct sched_ext_ops {
 	void (*runnable)(struct task_struct *p, u64 enq_flags);
 
 	/**
-	 * running - A task is starting to run on its associated CPU
+	 * @running: A task is starting to run on its associated CPU
 	 * @p: task starting to run
 	 *
 	 * See ->runnable() for explanation on the task state notifiers.
@@ -332,7 +332,7 @@ struct sched_ext_ops {
 	void (*running)(struct task_struct *p);
 
 	/**
-	 * stopping - A task is stopping execution
+	 * @stopping: A task is stopping execution
 	 * @p: task stopping to run
 	 * @runnable: is task @p still runnable?
 	 *
@@ -343,7 +343,7 @@ struct sched_ext_ops {
 	void (*stopping)(struct task_struct *p, bool runnable);
 
 	/**
-	 * quiescent - A task is becoming not runnable on its associated CPU
+	 * @quiescent: A task is becoming not runnable on its associated CPU
 	 * @p: task becoming not runnable
 	 * @deq_flags: %SCX_DEQ_*
 	 *
@@ -363,7 +363,7 @@ struct sched_ext_ops {
 	void (*quiescent)(struct task_struct *p, u64 deq_flags);
 
 	/**
-	 * yield - Yield CPU
+	 * @yield: Yield CPU
 	 * @from: yielding task
 	 * @to: optional yield target task
 	 *
@@ -378,7 +378,7 @@ struct sched_ext_ops {
 	bool (*yield)(struct task_struct *from, struct task_struct *to);
 
 	/**
-	 * core_sched_before - Task ordering for core-sched
+	 * @core_sched_before: Task ordering for core-sched
 	 * @a: task A
 	 * @b: task B
 	 *
@@ -396,7 +396,7 @@ struct sched_ext_ops {
 	bool (*core_sched_before)(struct task_struct *a, struct task_struct *b);
 
 	/**
-	 * set_weight - Set task weight
+	 * @set_weight: Set task weight
 	 * @p: task to set weight for
 	 * @weight: new weight [1..10000]
 	 *
@@ -405,7 +405,7 @@ struct sched_ext_ops {
 	void (*set_weight)(struct task_struct *p, u32 weight);
 
 	/**
-	 * set_cpumask - Set CPU affinity
+	 * @set_cpumask: Set CPU affinity
 	 * @p: task to set CPU affinity for
 	 * @cpumask: cpumask of cpus that @p can run on
 	 *
@@ -415,7 +415,7 @@ struct sched_ext_ops {
 			    const struct cpumask *cpumask);
 
 	/**
-	 * update_idle - Update the idle state of a CPU
+	 * @update_idle: Update the idle state of a CPU
 	 * @cpu: CPU to udpate the idle state for
 	 * @idle: whether entering or exiting the idle state
 	 *
@@ -436,7 +436,7 @@ struct sched_ext_ops {
 	void (*update_idle)(s32 cpu, bool idle);
 
 	/**
-	 * cpu_acquire - A CPU is becoming available to the BPF scheduler
+	 * @cpu_acquire: A CPU is becoming available to the BPF scheduler
 	 * @cpu: The CPU being acquired by the BPF scheduler.
 	 * @args: Acquire arguments, see the struct definition.
 	 *
@@ -446,7 +446,7 @@ struct sched_ext_ops {
 	void (*cpu_acquire)(s32 cpu, struct scx_cpu_acquire_args *args);
 
 	/**
-	 * cpu_release - A CPU is taken away from the BPF scheduler
+	 * @cpu_release: A CPU is taken away from the BPF scheduler
 	 * @cpu: The CPU being released by the BPF scheduler.
 	 * @args: Release arguments, see the struct definition.
 	 *
@@ -458,7 +458,7 @@ struct sched_ext_ops {
 	void (*cpu_release)(s32 cpu, struct scx_cpu_release_args *args);
 
 	/**
-	 * init_task - Initialize a task to run in a BPF scheduler
+	 * @init_task: Initialize a task to run in a BPF scheduler
 	 * @p: task to initialize for BPF scheduling
 	 * @args: init arguments, see the struct definition
 	 *
@@ -473,8 +473,9 @@ struct sched_ext_ops {
 	s32 (*init_task)(struct task_struct *p, struct scx_init_task_args *args);
 
 	/**
-	 * exit_task - Exit a previously-running task from the system
+	 * @exit_task: Exit a previously-running task from the system
 	 * @p: task to exit
+	 * @args: exit arguments, see the struct definition
 	 *
 	 * @p is exiting or the BPF scheduler is being unloaded. Perform any
 	 * necessary cleanup for @p.
@@ -482,7 +483,7 @@ struct sched_ext_ops {
 	void (*exit_task)(struct task_struct *p, struct scx_exit_task_args *args);
 
 	/**
-	 * enable - Enable BPF scheduling for a task
+	 * @enable: Enable BPF scheduling for a task
 	 * @p: task to enable BPF scheduling for
 	 *
 	 * Enable @p for BPF scheduling. enable() is called on @p any time it
@@ -491,7 +492,7 @@ struct sched_ext_ops {
 	void (*enable)(struct task_struct *p);
 
 	/**
-	 * disable - Disable BPF scheduling for a task
+	 * @disable: Disable BPF scheduling for a task
 	 * @p: task to disable BPF scheduling for
 	 *
 	 * @p is exiting, leaving SCX or the BPF scheduler is being unloaded.
@@ -501,7 +502,7 @@ struct sched_ext_ops {
 	void (*disable)(struct task_struct *p);
 
 	/**
-	 * dump - Dump BPF scheduler state on error
+	 * @dump: Dump BPF scheduler state on error
 	 * @ctx: debug dump context
 	 *
 	 * Use scx_bpf_dump() to generate BPF scheduler specific debug dump.
@@ -509,7 +510,7 @@ struct sched_ext_ops {
 	void (*dump)(struct scx_dump_ctx *ctx);
 
 	/**
-	 * dump_cpu - Dump BPF scheduler state for a CPU on error
+	 * @dump_cpu: Dump BPF scheduler state for a CPU on error
 	 * @ctx: debug dump context
 	 * @cpu: CPU to generate debug dump for
 	 * @idle: @cpu is currently idle without any runnable tasks
@@ -521,7 +522,7 @@ struct sched_ext_ops {
 	void (*dump_cpu)(struct scx_dump_ctx *ctx, s32 cpu, bool idle);
 
 	/**
-	 * dump_task - Dump BPF scheduler state for a runnable task on error
+	 * @dump_task: Dump BPF scheduler state for a runnable task on error
 	 * @ctx: debug dump context
 	 * @p: runnable task to generate debug dump for
 	 *
@@ -532,7 +533,7 @@ struct sched_ext_ops {
 
 #ifdef CONFIG_EXT_GROUP_SCHED
 	/**
-	 * cgroup_init - Initialize a cgroup
+	 * @cgroup_init: Initialize a cgroup
 	 * @cgrp: cgroup being initialized
 	 * @args: init arguments, see the struct definition
 	 *
@@ -547,7 +548,7 @@ struct sched_ext_ops {
 			   struct scx_cgroup_init_args *args);
 
 	/**
-	 * cgroup_exit - Exit a cgroup
+	 * @cgroup_exit: Exit a cgroup
 	 * @cgrp: cgroup being exited
 	 *
 	 * Either the BPF scheduler is being unloaded or @cgrp destroyed, exit
@@ -556,7 +557,7 @@ struct sched_ext_ops {
 	void (*cgroup_exit)(struct cgroup *cgrp);
 
 	/**
-	 * cgroup_prep_move - Prepare a task to be moved to a different cgroup
+	 * @cgroup_prep_move: Prepare a task to be moved to a different cgroup
 	 * @p: task being moved
 	 * @from: cgroup @p is being moved from
 	 * @to: cgroup @p is being moved to
@@ -571,7 +572,7 @@ struct sched_ext_ops {
 				struct cgroup *from, struct cgroup *to);
 
 	/**
-	 * cgroup_move - Commit cgroup move
+	 * @cgroup_move: Commit cgroup move
 	 * @p: task being moved
 	 * @from: cgroup @p is being moved from
 	 * @to: cgroup @p is being moved to
@@ -582,7 +583,7 @@ struct sched_ext_ops {
 			    struct cgroup *from, struct cgroup *to);
 
 	/**
-	 * cgroup_cancel_move - Cancel cgroup move
+	 * @cgroup_cancel_move: Cancel cgroup move
 	 * @p: task whose cgroup move is being canceled
 	 * @from: cgroup @p was being moved from
 	 * @to: cgroup @p was being moved to
@@ -594,7 +595,7 @@ struct sched_ext_ops {
 				   struct cgroup *from, struct cgroup *to);
 
 	/**
-	 * cgroup_set_weight - A cgroup's weight is being changed
+	 * @cgroup_set_weight: A cgroup's weight is being changed
 	 * @cgrp: cgroup whose weight is being updated
 	 * @weight: new weight [1..10000]
 	 *
@@ -608,7 +609,7 @@ struct sched_ext_ops {
 	 */
 
 	/**
-	 * cpu_online - A CPU became online
+	 * @cpu_online: A CPU became online
 	 * @cpu: CPU which just came up
 	 *
 	 * @cpu just came online. @cpu will not call ops.enqueue() or
@@ -617,7 +618,7 @@ struct sched_ext_ops {
 	void (*cpu_online)(s32 cpu);
 
 	/**
-	 * cpu_offline - A CPU is going offline
+	 * @cpu_offline: A CPU is going offline
 	 * @cpu: CPU which is going offline
 	 *
 	 * @cpu is going offline. @cpu will not call ops.enqueue() or
@@ -630,12 +631,12 @@ struct sched_ext_ops {
 	 */
 
 	/**
-	 * init - Initialize the BPF scheduler
+	 * @init: Initialize the BPF scheduler
 	 */
 	s32 (*init)(void);
 
 	/**
-	 * exit - Clean up after the BPF scheduler
+	 * @exit: Clean up after the BPF scheduler
 	 * @info: Exit info
 	 *
 	 * ops.exit() is also called on ops.init() failure, which is a bit
@@ -645,17 +646,17 @@ struct sched_ext_ops {
 	void (*exit)(struct scx_exit_info *info);
 
 	/**
-	 * dispatch_max_batch - Max nr of tasks that dispatch() can dispatch
+	 * @dispatch_max_batch: Max nr of tasks that dispatch() can dispatch
 	 */
 	u32 dispatch_max_batch;
 
 	/**
-	 * flags - %SCX_OPS_* flags
+	 * @flags: %SCX_OPS_* flags
 	 */
 	u64 flags;
 
 	/**
-	 * timeout_ms - The maximum amount of time, in milliseconds, that a
+	 * @timeout_ms: The maximum amount of time, in milliseconds, that a
 	 * runnable task should be able to wait before being scheduled. The
 	 * maximum timeout may not exceed the default timeout of 30 seconds.
 	 *
@@ -664,13 +665,13 @@ struct sched_ext_ops {
 	u32 timeout_ms;
 
 	/**
-	 * exit_dump_len - scx_exit_info.dump buffer length. If 0, the default
+	 * @exit_dump_len: scx_exit_info.dump buffer length. If 0, the default
 	 * value of 32768 is used.
 	 */
 	u32 exit_dump_len;
 
 	/**
-	 * hotplug_seq - A sequence number that may be set by the scheduler to
+	 * @hotplug_seq: A sequence number that may be set by the scheduler to
 	 * detect when a hotplug event has occurred during the loading process.
 	 * If 0, no detection occurs. Otherwise, the scheduler will fail to
 	 * load if the sequence number does not match @scx_hotplug_seq on the
@@ -679,7 +680,7 @@ struct sched_ext_ops {
 	u64 hotplug_seq;
 
 	/**
-	 * name - BPF scheduler's name
+	 * @name: BPF scheduler's name
 	 *
 	 * Must be a non-zero valid BPF object name including only isalnum(),
 	 * '_' and '.' chars. Shows up in kernel.sched_ext_ops sysctl while the
@@ -960,7 +961,7 @@ static DEFINE_PER_CPU(struct task_struct *, direct_dispatch_task);
 static struct scx_dispatch_q **global_dsqs;
 
 static const struct rhashtable_params dsq_hash_params = {
-	.key_len		= 8,
+	.key_len		= sizeof_field(struct scx_dispatch_q, id),
 	.key_offset		= offsetof(struct scx_dispatch_q, id),
 	.head_offset		= offsetof(struct scx_dispatch_q, hash_node),
 };
@@ -1408,7 +1409,6 @@ static struct task_struct *scx_task_iter_next(struct scx_task_iter *iter)
 /**
  * scx_task_iter_next_locked - Next non-idle task with its rq locked
  * @iter: iterator to walk
- * @include_dead: Whether we should include dead tasks in the iteration
  *
  * Visit the non-idle task with its rq lock held. Allows callers to specify
  * whether they would like to filter out dead tasks. See scx_task_iter_start()
@@ -3136,6 +3136,7 @@ static struct task_struct *pick_task_scx(struct rq *rq)
  * scx_prio_less - Task ordering for core-sched
  * @a: task A
  * @b: task B
+ * @in_fi: in forced idle state
  *
  * Core-sched is implemented as an additional scheduling layer on top of the
  * usual sched_class'es and needs to find out the expected task ordering. For
@@ -3184,6 +3185,10 @@ static bool test_and_clear_cpu_idle(int cpu)
 		 * scx_pick_idle_cpu() can get caught in an infinite loop as
 		 * @cpu is never cleared from idle_masks.smt. Ensure that @cpu
 		 * is eventually cleared.
+		 *
+		 * NOTE: Use cpumask_intersects() and cpumask_test_cpu() to
+		 * reduce memory writes, which may help alleviate cache
+		 * coherence pressure.
 		 */
 		if (cpumask_intersects(smt, idle_masks.smt))
 			cpumask_andnot(idle_masks.smt, idle_masks.smt, smt);
@@ -3220,6 +3225,74 @@ found:
 }
 
 /*
+ * Return the amount of CPUs in the same LLC domain of @cpu (or zero if the LLC
+ * domain is not defined).
+ */
+static unsigned int llc_weight(s32 cpu)
+{
+	struct sched_domain *sd;
+
+	sd = rcu_dereference(per_cpu(sd_llc, cpu));
+	if (!sd)
+		return 0;
+
+	return sd->span_weight;
+}
+
+/*
+ * Return the cpumask representing the LLC domain of @cpu (or NULL if the LLC
+ * domain is not defined).
+ */
+static struct cpumask *llc_span(s32 cpu)
+{
+	struct sched_domain *sd;
+
+	sd = rcu_dereference(per_cpu(sd_llc, cpu));
+	if (!sd)
+		return 0;
+
+	return sched_domain_span(sd);
+}
+
+/*
+ * Return the amount of CPUs in the same NUMA domain of @cpu (or zero if the
+ * NUMA domain is not defined).
+ */
+static unsigned int numa_weight(s32 cpu)
+{
+	struct sched_domain *sd;
+	struct sched_group *sg;
+
+	sd = rcu_dereference(per_cpu(sd_numa, cpu));
+	if (!sd)
+		return 0;
+	sg = sd->groups;
+	if (!sg)
+		return 0;
+
+	return sg->group_weight;
+}
+
+/*
+ * Return the cpumask representing the NUMA domain of @cpu (or NULL if the NUMA
+ * domain is not defined).
+ */
+static struct cpumask *numa_span(s32 cpu)
+{
+	struct sched_domain *sd;
+	struct sched_group *sg;
+
+	sd = rcu_dereference(per_cpu(sd_numa, cpu));
+	if (!sd)
+		return NULL;
+	sg = sd->groups;
+	if (!sg)
+		return NULL;
+
+	return sched_group_span(sg);
+}
+
+/*
  * Return true if the LLC domains do not perfectly overlap with the NUMA
  * domains, false otherwise.
  */
@@ -3250,19 +3323,10 @@ static bool llc_numa_mismatch(void)
 	 * overlapping, which is incorrect (as NUMA 1 has two distinct LLC
 	 * domains).
 	 */
-	for_each_online_cpu(cpu) {
-		const struct cpumask *numa_cpus;
-		struct sched_domain *sd;
-
-		sd = rcu_dereference(per_cpu(sd_llc, cpu));
-		if (!sd)
+	for_each_online_cpu(cpu)
+		if (llc_weight(cpu) != numa_weight(cpu))
 			return true;
 
-		numa_cpus = cpumask_of_node(cpu_to_node(cpu));
-		if (sd->span_weight != cpumask_weight(numa_cpus))
-			return true;
-	}
-
 	return false;
 }
 
@@ -3280,8 +3344,7 @@ static bool llc_numa_mismatch(void)
 static void update_selcpu_topology(void)
 {
 	bool enable_llc = false, enable_numa = false;
-	struct sched_domain *sd;
-	const struct cpumask *cpus;
+	unsigned int nr_cpus;
 	s32 cpu = cpumask_first(cpu_online_mask);
 
 	/*
@@ -3295,10 +3358,12 @@ static void update_selcpu_topology(void)
 	 * CPUs.
 	 */
 	rcu_read_lock();
-	sd = rcu_dereference(per_cpu(sd_llc, cpu));
-	if (sd) {
-		if (sd->span_weight < num_online_cpus())
+	nr_cpus = llc_weight(cpu);
+	if (nr_cpus > 0) {
+		if (nr_cpus < num_online_cpus())
 			enable_llc = true;
+		pr_debug("sched_ext: LLC=%*pb weight=%u\n",
+			 cpumask_pr_args(llc_span(cpu)), llc_weight(cpu));
 	}
 
 	/*
@@ -3310,15 +3375,19 @@ static void update_selcpu_topology(void)
 	 * enabling both NUMA and LLC optimizations is unnecessary, as checking
 	 * for an idle CPU in the same domain twice is redundant.
 	 */
-	cpus = cpumask_of_node(cpu_to_node(cpu));
-	if ((cpumask_weight(cpus) < num_online_cpus()) && llc_numa_mismatch())
-		enable_numa = true;
+	nr_cpus = numa_weight(cpu);
+	if (nr_cpus > 0) {
+		if (nr_cpus < num_online_cpus() && llc_numa_mismatch())
+			enable_numa = true;
+		pr_debug("sched_ext: NUMA=%*pb weight=%u\n",
+			 cpumask_pr_args(numa_span(cpu)), numa_weight(cpu));
+	}
 	rcu_read_unlock();
 
 	pr_debug("sched_ext: LLC idle selection %s\n",
-		 enable_llc ? "enabled" : "disabled");
+		 str_enabled_disabled(enable_llc));
 	pr_debug("sched_ext: NUMA idle selection %s\n",
-		 enable_numa ? "enabled" : "disabled");
+		 str_enabled_disabled(enable_numa));
 
 	if (enable_llc)
 		static_branch_enable_cpuslocked(&scx_selcpu_topo_llc);
@@ -3348,6 +3417,8 @@ static void update_selcpu_topology(void)
  * 4. Pick a CPU within the same NUMA node, if enabled:
  *   - choose a CPU from the same NUMA node to reduce memory access latency.
  *
+ * 5. Pick any idle CPU usable by the task.
+ *
  * Step 3 and 4 are performed only if the system has, respectively, multiple
  * LLC domains / multiple NUMA nodes (see scx_selcpu_topo_llc and
  * scx_selcpu_topo_numa).
@@ -3364,7 +3435,6 @@ static s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu,
 
 	*found = false;
 
-
 	/*
 	 * This is necessary to protect llc_cpus.
 	 */
@@ -3383,15 +3453,10 @@ static s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu,
 	 */
 	if (p->nr_cpus_allowed >= num_possible_cpus()) {
 		if (static_branch_maybe(CONFIG_NUMA, &scx_selcpu_topo_numa))
-			numa_cpus = cpumask_of_node(cpu_to_node(prev_cpu));
-
-		if (static_branch_maybe(CONFIG_SCHED_MC, &scx_selcpu_topo_llc)) {
-			struct sched_domain *sd;
+			numa_cpus = numa_span(prev_cpu);
 
-			sd = rcu_dereference(per_cpu(sd_llc, prev_cpu));
-			if (sd)
-				llc_cpus = sched_domain_span(sd);
-		}
+		if (static_branch_maybe(CONFIG_SCHED_MC, &scx_selcpu_topo_llc))
+			llc_cpus = llc_span(prev_cpu);
 	}
 
 	/*
@@ -3592,10 +3657,7 @@ static void reset_idle_masks(void)
 
 static void update_builtin_idle(int cpu, bool idle)
 {
-	if (idle)
-		cpumask_set_cpu(cpu, idle_masks.cpu);
-	else
-		cpumask_clear_cpu(cpu, idle_masks.cpu);
+	assign_cpu(cpu, idle_masks.cpu, idle);
 
 #ifdef CONFIG_SCHED_SMT
 	if (sched_smt_active()) {
@@ -3606,10 +3668,8 @@ static void update_builtin_idle(int cpu, bool idle)
 			 * idle_masks.smt handling is racy but that's fine as
 			 * it's only for optimization and self-correcting.
 			 */
-			for_each_cpu(cpu, smt) {
-				if (!cpumask_test_cpu(cpu, idle_masks.cpu))
-					return;
-			}
+			if (!cpumask_subset(smt, idle_masks.cpu))
+				return;
 			cpumask_or(idle_masks.smt, idle_masks.smt, smt);
 		} else {
 			cpumask_andnot(idle_masks.smt, idle_masks.smt, smt);
@@ -4688,6 +4748,7 @@ bool task_should_scx(int policy)
 
 /**
  * scx_softlockup - sched_ext softlockup handler
+ * @dur_s: number of seconds of CPU stuck due to soft lockup
  *
  * On some multi-socket setups (e.g. 2x Intel 8480c), the BPF scheduler can
  * live-lock the system by making many CPUs target the same DSQ to the point
@@ -4731,6 +4792,7 @@ static void scx_clear_softlockup(void)
 
 /**
  * scx_ops_bypass - [Un]bypass scx_ops and guarantee forward progress
+ * @bypass: true for bypass, false for unbypass
  *
  * Bypassing guarantees that all runnable tasks make forward progress without
  * trusting the BPF scheduler. We can't grab any mutexes or rwsems as they might
@@ -4899,7 +4961,7 @@ static void scx_ops_disable_workfn(struct kthread_work *work)
 	struct task_struct *p;
 	struct rhashtable_iter rht_iter;
 	struct scx_dispatch_q *dsq;
-	int i, kind;
+	int i, kind, cpu;
 
 	kind = atomic_read(&scx_exit_kind);
 	while (true) {
@@ -4982,6 +5044,15 @@ static void scx_ops_disable_workfn(struct kthread_work *work)
 	scx_task_iter_stop(&sti);
 	percpu_up_write(&scx_fork_rwsem);
 
+	/*
+	 * Invalidate all the rq clocks to prevent getting outdated
+	 * rq clocks from a previous scx scheduler.
+	 */
+	for_each_possible_cpu(cpu) {
+		struct rq *rq = cpu_rq(cpu);
+		scx_rq_clock_invalidate(rq);
+	}
+
 	/* no task is on scx, turn off all the switches and flush in-progress calls */
 	static_branch_disable(&__scx_ops_enabled);
 	for (i = SCX_OPI_BEGIN; i < SCX_OPI_END; i++)
@@ -5206,9 +5277,9 @@ static void scx_dump_task(struct seq_buf *s, struct scx_dump_ctx *dctx,
 		  scx_get_task_state(p), p->scx.flags & ~SCX_TASK_STATE_MASK,
 		  p->scx.dsq_flags, ops_state & SCX_OPSS_STATE_MASK,
 		  ops_state >> SCX_OPSS_QSEQ_SHIFT);
-	dump_line(s, "      sticky/holding_cpu=%d/%d dsq_id=%s dsq_vtime=%llu",
+	dump_line(s, "      sticky/holding_cpu=%d/%d dsq_id=%s dsq_vtime=%llu slice=%llu",
 		  p->scx.sticky_cpu, p->scx.holding_cpu, dsq_id_buf,
-		  p->scx.dsq_vtime);
+		  p->scx.dsq_vtime, p->scx.slice);
 	dump_line(s, "      cpus=%*pb", cpumask_pr_args(p->cpus_ptr));
 
 	if (SCX_HAS_OP(dump_task)) {
@@ -6283,6 +6354,15 @@ void __init init_sched_ext_class(void)
 
 __bpf_kfunc_start_defs();
 
+static bool check_builtin_idle_enabled(void)
+{
+	if (static_branch_likely(&scx_builtin_idle_enabled))
+		return true;
+
+	scx_ops_error("built-in idle tracking is disabled");
+	return false;
+}
+
 /**
  * scx_bpf_select_cpu_dfl - The default implementation of ops.select_cpu()
  * @p: task_struct to select a CPU for
@@ -6300,10 +6380,8 @@ __bpf_kfunc_start_defs();
 __bpf_kfunc s32 scx_bpf_select_cpu_dfl(struct task_struct *p, s32 prev_cpu,
 				       u64 wake_flags, bool *is_idle)
 {
-	if (!static_branch_likely(&scx_builtin_idle_enabled)) {
-		scx_ops_error("built-in idle tracking is disabled");
+	if (!check_builtin_idle_enabled())
 		goto prev_cpu;
-	}
 
 	if (!scx_kf_allowed(SCX_KF_SELECT_CPU))
 		goto prev_cpu;
@@ -6387,9 +6465,7 @@ __bpf_kfunc_start_defs();
  * ops.select_cpu(), and ops.dispatch().
  *
  * When called from ops.select_cpu() or ops.enqueue(), it's for direct dispatch
- * and @p must match the task being enqueued. Also, %SCX_DSQ_LOCAL_ON can't be
- * used to target the local DSQ of a CPU other than the enqueueing one. Use
- * ops.select_cpu() to be on the target CPU in the first place.
+ * and @p must match the task being enqueued.
  *
  * When called from ops.select_cpu(), @enq_flags and @dsp_id are stored, and @p
  * will be directly inserted into the corresponding dispatch queue after
@@ -7228,7 +7304,7 @@ __bpf_kfunc void scx_bpf_error_bstr(char *fmt, unsigned long long *data,
 }
 
 /**
- * scx_bpf_dump - Generate extra debug dump specific to the BPF scheduler
+ * scx_bpf_dump_bstr - Generate extra debug dump specific to the BPF scheduler
  * @fmt: format string
  * @data: format string parameters packaged using ___bpf_fill() macro
  * @data__sz: @data len, must end in '__sz' for the verifier
@@ -7320,7 +7396,6 @@ __bpf_kfunc u32 scx_bpf_cpuperf_cur(s32 cpu)
  * scx_bpf_cpuperf_set - Set the relative performance target of a CPU
  * @cpu: CPU of interest
  * @perf: target performance level [0, %SCX_CPUPERF_ONE]
- * @flags: %SCX_CPUPERF_* flags
  *
  * Set the target performance level of @cpu to @perf. @perf is in linear
  * relative scale between 0 and %SCX_CPUPERF_ONE. This determines how the
@@ -7397,10 +7472,8 @@ __bpf_kfunc void scx_bpf_put_cpumask(const struct cpumask *cpumask)
  */
 __bpf_kfunc const struct cpumask *scx_bpf_get_idle_cpumask(void)
 {
-	if (!static_branch_likely(&scx_builtin_idle_enabled)) {
-		scx_ops_error("built-in idle tracking is disabled");
+	if (!check_builtin_idle_enabled())
 		return cpu_none_mask;
-	}
 
 #ifdef CONFIG_SMP
 	return idle_masks.cpu;
@@ -7418,10 +7491,8 @@ __bpf_kfunc const struct cpumask *scx_bpf_get_idle_cpumask(void)
  */
 __bpf_kfunc const struct cpumask *scx_bpf_get_idle_smtmask(void)
 {
-	if (!static_branch_likely(&scx_builtin_idle_enabled)) {
-		scx_ops_error("built-in idle tracking is disabled");
+	if (!check_builtin_idle_enabled())
 		return cpu_none_mask;
-	}
 
 #ifdef CONFIG_SMP
 	if (sched_smt_active())
@@ -7436,6 +7507,7 @@ __bpf_kfunc const struct cpumask *scx_bpf_get_idle_smtmask(void)
 /**
  * scx_bpf_put_idle_cpumask - Release a previously acquired referenced kptr to
  * either the percpu, or SMT idle-tracking cpumask.
+ * @idle_mask: &cpumask to use
  */
 __bpf_kfunc void scx_bpf_put_idle_cpumask(const struct cpumask *idle_mask)
 {
@@ -7459,10 +7531,8 @@ __bpf_kfunc void scx_bpf_put_idle_cpumask(const struct cpumask *idle_mask)
  */
 __bpf_kfunc bool scx_bpf_test_and_clear_cpu_idle(s32 cpu)
 {
-	if (!static_branch_likely(&scx_builtin_idle_enabled)) {
-		scx_ops_error("built-in idle tracking is disabled");
+	if (!check_builtin_idle_enabled())
 		return false;
-	}
 
 	if (ops_cpu_valid(cpu, NULL))
 		return test_and_clear_cpu_idle(cpu);
@@ -7492,10 +7562,8 @@ __bpf_kfunc bool scx_bpf_test_and_clear_cpu_idle(s32 cpu)
 __bpf_kfunc s32 scx_bpf_pick_idle_cpu(const struct cpumask *cpus_allowed,
 				      u64 flags)
 {
-	if (!static_branch_likely(&scx_builtin_idle_enabled)) {
-		scx_ops_error("built-in idle tracking is disabled");
+	if (!check_builtin_idle_enabled())
 		return -EBUSY;
-	}
 
 	return scx_pick_idle_cpu(cpus_allowed, flags);
 }
@@ -7590,6 +7658,68 @@ out:
 }
 #endif
 
+/**
+ * scx_bpf_now - Returns a high-performance monotonically non-decreasing
+ * clock for the current CPU. The clock returned is in nanoseconds.
+ *
+ * It provides the following properties:
+ *
+ * 1) High performance: Many BPF schedulers call bpf_ktime_get_ns() frequently
+ *  to account for execution time and track tasks' runtime properties.
+ *  Unfortunately, in some hardware platforms, bpf_ktime_get_ns() -- which
+ *  eventually reads a hardware timestamp counter -- is neither performant nor
+ *  scalable. scx_bpf_now() aims to provide a high-performance clock by
+ *  using the rq clock in the scheduler core whenever possible.
+ *
+ * 2) High enough resolution for the BPF scheduler use cases: In most BPF
+ *  scheduler use cases, the required clock resolution is lower than the most
+ *  accurate hardware clock (e.g., rdtsc in x86). scx_bpf_now() basically
+ *  uses the rq clock in the scheduler core whenever it is valid. It considers
+ *  that the rq clock is valid from the time the rq clock is updated
+ *  (update_rq_clock) until the rq is unlocked (rq_unpin_lock).
+ *
+ * 3) Monotonically non-decreasing clock for the same CPU: scx_bpf_now()
+ *  guarantees the clock never goes backward when comparing them in the same
+ *  CPU. On the other hand, when comparing clocks in different CPUs, there
+ *  is no such guarantee -- the clock can go backward. It provides a
+ *  monotonically *non-decreasing* clock so that it would provide the same
+ *  clock values in two different scx_bpf_now() calls in the same CPU
+ *  during the same period of when the rq clock is valid.
+ */
+__bpf_kfunc u64 scx_bpf_now(void)
+{
+	struct rq *rq;
+	u64 clock;
+
+	preempt_disable();
+
+	rq = this_rq();
+	if (smp_load_acquire(&rq->scx.flags) & SCX_RQ_CLK_VALID) {
+		/*
+		 * If the rq clock is valid, use the cached rq clock.
+		 *
+		 * Note that scx_bpf_now() is re-entrant between a process
+		 * context and an interrupt context (e.g., timer interrupt).
+		 * However, we don't need to consider the race between them
+		 * because such race is not observable from a caller.
+		 */
+		clock = READ_ONCE(rq->scx.clock);
+	} else {
+		/*
+		 * Otherwise, return a fresh rq clock.
+		 *
+		 * The rq clock is updated outside of the rq lock.
+		 * In this case, keep the updated rq clock invalid so the next
+		 * kfunc call outside the rq lock gets a fresh rq clock.
+		 */
+		clock = sched_clock_cpu(cpu_of(rq));
+	}
+
+	preempt_enable();
+
+	return clock;
+}
+
 __bpf_kfunc_end_defs();
 
 BTF_KFUNCS_START(scx_kfunc_ids_any)
@@ -7621,6 +7751,7 @@ BTF_ID_FLAGS(func, scx_bpf_cpu_rq)
 #ifdef CONFIG_CGROUP_SCHED
 BTF_ID_FLAGS(func, scx_bpf_task_cgroup, KF_RCU | KF_ACQUIRE)
 #endif
+BTF_ID_FLAGS(func, scx_bpf_now)
 BTF_KFUNCS_END(scx_kfunc_ids_any)
 
 static const struct btf_kfunc_id_set scx_kfunc_set_any = {
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c7cf4cc57cdd..38e0e323dda2 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -759,6 +759,7 @@ enum scx_rq_flags {
 	SCX_RQ_BAL_PENDING	= 1 << 2, /* balance hasn't run yet */
 	SCX_RQ_BAL_KEEP		= 1 << 3, /* balance decided to keep current */
 	SCX_RQ_BYPASSING	= 1 << 4,
+	SCX_RQ_CLK_VALID	= 1 << 5, /* RQ clock is fresh and valid */
 
 	SCX_RQ_IN_WAKEUP	= 1 << 16,
 	SCX_RQ_IN_BALANCE	= 1 << 17,
@@ -771,9 +772,10 @@ struct scx_rq {
 	unsigned long		ops_qseq;
 	u64			extra_enq_flags;	/* see move_task_to_local_dsq() */
 	u32			nr_running;
-	u32			flags;
 	u32			cpuperf_target;		/* [0, SCHED_CAPACITY_SCALE] */
 	bool			cpu_released;
+	u32			flags;
+	u64			clock;			/* current per-rq clock -- see scx_bpf_now() */
 	cpumask_var_t		cpus_to_kick;
 	cpumask_var_t		cpus_to_kick_if_idle;
 	cpumask_var_t		cpus_to_preempt;
@@ -1722,6 +1724,38 @@ struct rq_flags {
 
 extern struct balance_callback balance_push_callback;
 
+#ifdef CONFIG_SCHED_CLASS_EXT
+extern const struct sched_class ext_sched_class;
+
+DECLARE_STATIC_KEY_FALSE(__scx_ops_enabled);	/* SCX BPF scheduler loaded */
+DECLARE_STATIC_KEY_FALSE(__scx_switched_all);	/* all fair class tasks on SCX */
+
+#define scx_enabled()		static_branch_unlikely(&__scx_ops_enabled)
+#define scx_switched_all()	static_branch_unlikely(&__scx_switched_all)
+
+static inline void scx_rq_clock_update(struct rq *rq, u64 clock)
+{
+	if (!scx_enabled())
+		return;
+	WRITE_ONCE(rq->scx.clock, clock);
+	smp_store_release(&rq->scx.flags, rq->scx.flags | SCX_RQ_CLK_VALID);
+}
+
+static inline void scx_rq_clock_invalidate(struct rq *rq)
+{
+	if (!scx_enabled())
+		return;
+	WRITE_ONCE(rq->scx.flags, rq->scx.flags & ~SCX_RQ_CLK_VALID);
+}
+
+#else /* !CONFIG_SCHED_CLASS_EXT */
+#define scx_enabled()		false
+#define scx_switched_all()	false
+
+static inline void scx_rq_clock_update(struct rq *rq, u64 clock) {}
+static inline void scx_rq_clock_invalidate(struct rq *rq) {}
+#endif /* !CONFIG_SCHED_CLASS_EXT */
+
 /*
  * Lockdep annotation that avoids accidental unlocks; it's like a
  * sticky/continuous lockdep_assert_held().
@@ -1751,7 +1785,7 @@ static inline void rq_unpin_lock(struct rq *rq, struct rq_flags *rf)
 	if (rq->clock_update_flags > RQCF_ACT_SKIP)
 		rf->clock_update_flags = RQCF_UPDATED;
 #endif
-
+	scx_rq_clock_invalidate(rq);
 	lockdep_unpin_lock(__rq_lockp(rq), rf->cookie);
 }
 
@@ -2510,19 +2544,6 @@ extern const struct sched_class rt_sched_class;
 extern const struct sched_class fair_sched_class;
 extern const struct sched_class idle_sched_class;
 
-#ifdef CONFIG_SCHED_CLASS_EXT
-extern const struct sched_class ext_sched_class;
-
-DECLARE_STATIC_KEY_FALSE(__scx_ops_enabled);	/* SCX BPF scheduler loaded */
-DECLARE_STATIC_KEY_FALSE(__scx_switched_all);	/* all fair class tasks on SCX */
-
-#define scx_enabled()		static_branch_unlikely(&__scx_ops_enabled)
-#define scx_switched_all()	static_branch_unlikely(&__scx_switched_all)
-#else /* !CONFIG_SCHED_CLASS_EXT */
-#define scx_enabled()		false
-#define scx_switched_all()	false
-#endif /* !CONFIG_SCHED_CLASS_EXT */
-
 /*
  * Iterate only active classes. SCX can take over all fair tasks or be
  * completely disabled. If the former, skip fair. If the latter, skip SCX.
diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h
index 625f5b046776..f3e15e9efa76 100644
--- a/tools/sched_ext/include/scx/common.bpf.h
+++ b/tools/sched_ext/include/scx/common.bpf.h
@@ -9,7 +9,7 @@
 
 #ifdef LSP
 #define __bpf__
-#include "../vmlinux/vmlinux.h"
+#include "../vmlinux.h"
 #else
 #include "vmlinux.h"
 #endif
@@ -24,6 +24,10 @@
 #define PF_EXITING			0x00000004
 #define CLOCK_MONOTONIC			1
 
+extern int LINUX_KERNEL_VERSION __kconfig;
+extern const char CONFIG_CC_VERSION_TEXT[64] __kconfig __weak;
+extern const char CONFIG_LOCALVERSION[64] __kconfig __weak;
+
 /*
  * Earlier versions of clang/pahole lost upper 32bits in 64bit enums which can
  * lead to really confusing misbehaviors. Let's trigger a build failure.
@@ -72,6 +76,7 @@ bool scx_bpf_task_running(const struct task_struct *p) __ksym;
 s32 scx_bpf_task_cpu(const struct task_struct *p) __ksym;
 struct rq *scx_bpf_cpu_rq(s32 cpu) __ksym;
 struct cgroup *scx_bpf_task_cgroup(struct task_struct *p) __ksym __weak;
+u64 scx_bpf_now(void) __ksym __weak;
 
 /*
  * Use the following as @it__iter when calling scx_bpf_dsq_move[_vtime]() from
@@ -98,7 +103,7 @@ void ___scx_bpf_bstr_format_checker(const char *fmt, ...) {}
 	_Pragma("GCC diagnostic push")						\
 	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")			\
 	___bpf_fill(___param, args);						\
-	_Pragma("GCC diagnostic pop")						\
+	_Pragma("GCC diagnostic pop")
 
 /*
  * scx_bpf_exit() wraps the scx_bpf_exit_bstr() kfunc with variadic arguments
@@ -136,6 +141,20 @@ void ___scx_bpf_bstr_format_checker(const char *fmt, ...) {}
 	___scx_bpf_bstr_format_checker(fmt, ##args);				\
 })
 
+/*
+ * scx_bpf_dump_header() is a wrapper around scx_bpf_dump that adds a header
+ * of system information for debugging.
+ */
+#define scx_bpf_dump_header()							\
+({										\
+	scx_bpf_dump("kernel: %d.%d.%d %s\ncc: %s\n",				\
+		     LINUX_KERNEL_VERSION >> 16,				\
+		     LINUX_KERNEL_VERSION >> 8 & 0xFF,				\
+		     LINUX_KERNEL_VERSION & 0xFF,				\
+		     CONFIG_LOCALVERSION,					\
+		     CONFIG_CC_VERSION_TEXT);					\
+})
+
 #define BPF_STRUCT_OPS(name, args...)						\
 SEC("struct_ops/"#name)								\
 BPF_PROG(name, ##args)
@@ -317,6 +336,66 @@ u32 bpf_cpumask_any_and_distribute(const struct cpumask *src1,
 				   const struct cpumask *src2) __ksym;
 u32 bpf_cpumask_weight(const struct cpumask *cpumask) __ksym;
 
+int bpf_iter_bits_new(struct bpf_iter_bits *it, const u64 *unsafe_ptr__ign, u32 nr_words) __ksym;
+int *bpf_iter_bits_next(struct bpf_iter_bits *it) __ksym;
+void bpf_iter_bits_destroy(struct bpf_iter_bits *it) __ksym;
+
+#define def_iter_struct(name)							\
+struct bpf_iter_##name {							\
+    struct bpf_iter_bits it;							\
+    const struct cpumask *bitmap;						\
+};
+
+#define def_iter_new(name)							\
+static inline int bpf_iter_##name##_new(					\
+	struct bpf_iter_##name *it, const u64 *unsafe_ptr__ign, u32 nr_words)	\
+{										\
+	it->bitmap = scx_bpf_get_##name##_cpumask();				\
+	return bpf_iter_bits_new(&it->it, (const u64 *)it->bitmap,		\
+				 sizeof(struct cpumask) / 8);			\
+}
+
+#define def_iter_next(name)							\
+static inline int *bpf_iter_##name##_next(struct bpf_iter_##name *it) {		\
+	return bpf_iter_bits_next(&it->it);					\
+}
+
+#define def_iter_destroy(name)							\
+static inline void bpf_iter_##name##_destroy(struct bpf_iter_##name *it) {	\
+	scx_bpf_put_cpumask(it->bitmap);					\
+	bpf_iter_bits_destroy(&it->it);						\
+}
+#define def_for_each_cpu(cpu, name) for_each_##name##_cpu(cpu)
+
+/// Provides iterator for possible and online cpus.
+///
+/// # Example
+///
+/// ```
+/// static inline void example_use() {
+///     int *cpu;
+///
+///     for_each_possible_cpu(cpu){
+///         bpf_printk("CPU %d is possible", *cpu);
+///     }
+///
+///     for_each_online_cpu(cpu){
+///         bpf_printk("CPU %d is online", *cpu);
+///     }
+/// }
+/// ```
+def_iter_struct(possible);
+def_iter_new(possible);
+def_iter_next(possible);
+def_iter_destroy(possible);
+#define for_each_possible_cpu(cpu) bpf_for_each(possible, cpu, NULL, 0)
+
+def_iter_struct(online);
+def_iter_new(online);
+def_iter_next(online);
+def_iter_destroy(online);
+#define for_each_online_cpu(cpu) bpf_for_each(online, cpu, NULL, 0)
+
 /*
  * Access a cpumask in read-only mode (typically to check bits).
  */
@@ -329,6 +408,100 @@ static __always_inline const struct cpumask *cast_mask(struct bpf_cpumask *mask)
 void bpf_rcu_read_lock(void) __ksym;
 void bpf_rcu_read_unlock(void) __ksym;
 
+/*
+ * Time helpers, most of which are from jiffies.h.
+ */
+
+/**
+ * time_delta - Calculate the delta between new and old time stamp
+ * @after: first comparable as u64
+ * @before: second comparable as u64
+ *
+ * Return: the time difference, which is >= 0
+ */
+static inline s64 time_delta(u64 after, u64 before)
+{
+	return (s64)(after - before) > 0 ? : 0;
+}
+
+/**
+ * time_after - returns true if the time a is after time b.
+ * @a: first comparable as u64
+ * @b: second comparable as u64
+ *
+ * Do this with "<0" and ">=0" to only test the sign of the result. A
+ * good compiler would generate better code (and a really good compiler
+ * wouldn't care). Gcc is currently neither.
+ *
+ * Return: %true is time a is after time b, otherwise %false.
+ */
+static inline bool time_after(u64 a, u64 b)
+{
+	 return (s64)(b - a) < 0;
+}
+
+/**
+ * time_before - returns true if the time a is before time b.
+ * @a: first comparable as u64
+ * @b: second comparable as u64
+ *
+ * Return: %true is time a is before time b, otherwise %false.
+ */
+static inline bool time_before(u64 a, u64 b)
+{
+	return time_after(b, a);
+}
+
+/**
+ * time_after_eq - returns true if the time a is after or the same as time b.
+ * @a: first comparable as u64
+ * @b: second comparable as u64
+ *
+ * Return: %true is time a is after or the same as time b, otherwise %false.
+ */
+static inline bool time_after_eq(u64 a, u64 b)
+{
+	 return (s64)(a - b) >= 0;
+}
+
+/**
+ * time_before_eq - returns true if the time a is before or the same as time b.
+ * @a: first comparable as u64
+ * @b: second comparable as u64
+ *
+ * Return: %true is time a is before or the same as time b, otherwise %false.
+ */
+static inline bool time_before_eq(u64 a, u64 b)
+{
+	return time_after_eq(b, a);
+}
+
+/**
+ * time_in_range - Calculate whether a is in the range of [b, c].
+ * @a: time to test
+ * @b: beginning of the range
+ * @c: end of the range
+ *
+ * Return: %true is time a is in the range [b, c], otherwise %false.
+ */
+static inline bool time_in_range(u64 a, u64 b, u64 c)
+{
+	return time_after_eq(a, b) && time_before_eq(a, c);
+}
+
+/**
+ * time_in_range_open - Calculate whether a is in the range of [b, c).
+ * @a: time to test
+ * @b: beginning of the range
+ * @c: end of the range
+ *
+ * Return: %true is time a is in the range [b, c), otherwise %false.
+ */
+static inline bool time_in_range_open(u64 a, u64 b, u64 c)
+{
+	return time_after_eq(a, b) && time_before(a, c);
+}
+
 
 /*
  * Other helpers
@@ -423,5 +596,6 @@ static inline u32 log2_u64(u64 v)
 }
 
 #include "compat.bpf.h"
+#include "enums.bpf.h"
 
 #endif	/* __SCX_COMMON_BPF_H */
diff --git a/tools/sched_ext/include/scx/common.h b/tools/sched_ext/include/scx/common.h
index 5b0f90152152..dc18b99e55cd 100644
--- a/tools/sched_ext/include/scx/common.h
+++ b/tools/sched_ext/include/scx/common.h
@@ -71,5 +71,11 @@ typedef int64_t s64;
 
 #include "user_exit_info.h"
 #include "compat.h"
+#include "enums.h"
+
+/* not available when building kernel tools/sched_ext */
+#if __has_include(<lib/sdt_task.h>)
+#include <lib/sdt_task.h>
+#endif
 
 #endif	/* __SCHED_EXT_COMMON_H */
diff --git a/tools/sched_ext/include/scx/compat.bpf.h b/tools/sched_ext/include/scx/compat.bpf.h
index d56520100a26..50e1499ae093 100644
--- a/tools/sched_ext/include/scx/compat.bpf.h
+++ b/tools/sched_ext/include/scx/compat.bpf.h
@@ -125,6 +125,11 @@ bool scx_bpf_dispatch_vtime_from_dsq___compat(struct bpf_iter_scx_dsq *it__iter,
 	false;									\
 })
 
+#define scx_bpf_now()								\
+	(bpf_ksym_exists(scx_bpf_now) ?						\
+	 scx_bpf_now() :							\
+	 bpf_ktime_get_ns())
+
 /*
  * Define sched_ext_ops. This may be expanded to define multiple variants for
  * backward compatibility. See compat.h::SCX_OPS_LOAD/ATTACH().
diff --git a/tools/sched_ext/include/scx/compat.h b/tools/sched_ext/include/scx/compat.h
index cc56ff9aa252..b50280e2ba2b 100644
--- a/tools/sched_ext/include/scx/compat.h
+++ b/tools/sched_ext/include/scx/compat.h
@@ -149,6 +149,7 @@ static inline long scx_hotplug_seq(void)
 	__skel = __scx_name##__open();						\
 	SCX_BUG_ON(!__skel, "Could not open " #__scx_name);			\
 	__skel->struct_ops.__ops_name->hotplug_seq = scx_hotplug_seq();		\
+	SCX_ENUM_INIT(__skel);							\
 	__skel; 								\
 })
 
diff --git a/tools/sched_ext/include/scx/enums.autogen.bpf.h b/tools/sched_ext/include/scx/enums.autogen.bpf.h
new file mode 100644
index 000000000000..0e941a0d6f88
--- /dev/null
+++ b/tools/sched_ext/include/scx/enums.autogen.bpf.h
@@ -0,0 +1,105 @@
+/*
+ * WARNING: This file is autogenerated from scripts/gen_enums.py. If you would
+ * like to access an enum that is currently missing, add it to the script
+ * and run it from the root directory to update this file.
+ */
+
+const volatile u64 __SCX_OPS_NAME_LEN __weak;
+#define SCX_OPS_NAME_LEN __SCX_OPS_NAME_LEN
+
+const volatile u64 __SCX_SLICE_DFL __weak;
+#define SCX_SLICE_DFL __SCX_SLICE_DFL
+
+const volatile u64 __SCX_SLICE_INF __weak;
+#define SCX_SLICE_INF __SCX_SLICE_INF
+
+const volatile u64 __SCX_DSQ_FLAG_BUILTIN __weak;
+#define SCX_DSQ_FLAG_BUILTIN __SCX_DSQ_FLAG_BUILTIN
+
+const volatile u64 __SCX_DSQ_FLAG_LOCAL_ON __weak;
+#define SCX_DSQ_FLAG_LOCAL_ON __SCX_DSQ_FLAG_LOCAL_ON
+
+const volatile u64 __SCX_DSQ_INVALID __weak;
+#define SCX_DSQ_INVALID __SCX_DSQ_INVALID
+
+const volatile u64 __SCX_DSQ_GLOBAL __weak;
+#define SCX_DSQ_GLOBAL __SCX_DSQ_GLOBAL
+
+const volatile u64 __SCX_DSQ_LOCAL __weak;
+#define SCX_DSQ_LOCAL __SCX_DSQ_LOCAL
+
+const volatile u64 __SCX_DSQ_LOCAL_ON __weak;
+#define SCX_DSQ_LOCAL_ON __SCX_DSQ_LOCAL_ON
+
+const volatile u64 __SCX_DSQ_LOCAL_CPU_MASK __weak;
+#define SCX_DSQ_LOCAL_CPU_MASK __SCX_DSQ_LOCAL_CPU_MASK
+
+const volatile u64 __SCX_TASK_QUEUED __weak;
+#define SCX_TASK_QUEUED __SCX_TASK_QUEUED
+
+const volatile u64 __SCX_TASK_RESET_RUNNABLE_AT __weak;
+#define SCX_TASK_RESET_RUNNABLE_AT __SCX_TASK_RESET_RUNNABLE_AT
+
+const volatile u64 __SCX_TASK_DEQD_FOR_SLEEP __weak;
+#define SCX_TASK_DEQD_FOR_SLEEP __SCX_TASK_DEQD_FOR_SLEEP
+
+const volatile u64 __SCX_TASK_STATE_SHIFT __weak;
+#define SCX_TASK_STATE_SHIFT __SCX_TASK_STATE_SHIFT
+
+const volatile u64 __SCX_TASK_STATE_BITS __weak;
+#define SCX_TASK_STATE_BITS __SCX_TASK_STATE_BITS
+
+const volatile u64 __SCX_TASK_STATE_MASK __weak;
+#define SCX_TASK_STATE_MASK __SCX_TASK_STATE_MASK
+
+const volatile u64 __SCX_TASK_CURSOR __weak;
+#define SCX_TASK_CURSOR __SCX_TASK_CURSOR
+
+const volatile u64 __SCX_TASK_NONE __weak;
+#define SCX_TASK_NONE __SCX_TASK_NONE
+
+const volatile u64 __SCX_TASK_INIT __weak;
+#define SCX_TASK_INIT __SCX_TASK_INIT
+
+const volatile u64 __SCX_TASK_READY __weak;
+#define SCX_TASK_READY __SCX_TASK_READY
+
+const volatile u64 __SCX_TASK_ENABLED __weak;
+#define SCX_TASK_ENABLED __SCX_TASK_ENABLED
+
+const volatile u64 __SCX_TASK_NR_STATES __weak;
+#define SCX_TASK_NR_STATES __SCX_TASK_NR_STATES
+
+const volatile u64 __SCX_TASK_DSQ_ON_PRIQ __weak;
+#define SCX_TASK_DSQ_ON_PRIQ __SCX_TASK_DSQ_ON_PRIQ
+
+const volatile u64 __SCX_KICK_IDLE __weak;
+#define SCX_KICK_IDLE __SCX_KICK_IDLE
+
+const volatile u64 __SCX_KICK_PREEMPT __weak;
+#define SCX_KICK_PREEMPT __SCX_KICK_PREEMPT
+
+const volatile u64 __SCX_KICK_WAIT __weak;
+#define SCX_KICK_WAIT __SCX_KICK_WAIT
+
+const volatile u64 __SCX_ENQ_WAKEUP __weak;
+#define SCX_ENQ_WAKEUP __SCX_ENQ_WAKEUP
+
+const volatile u64 __SCX_ENQ_HEAD __weak;
+#define SCX_ENQ_HEAD __SCX_ENQ_HEAD
+
+const volatile u64 __SCX_ENQ_PREEMPT __weak;
+#define SCX_ENQ_PREEMPT __SCX_ENQ_PREEMPT
+
+const volatile u64 __SCX_ENQ_REENQ __weak;
+#define SCX_ENQ_REENQ __SCX_ENQ_REENQ
+
+const volatile u64 __SCX_ENQ_LAST __weak;
+#define SCX_ENQ_LAST __SCX_ENQ_LAST
+
+const volatile u64 __SCX_ENQ_CLEAR_OPSS __weak;
+#define SCX_ENQ_CLEAR_OPSS __SCX_ENQ_CLEAR_OPSS
+
+const volatile u64 __SCX_ENQ_DSQ_PRIQ __weak;
+#define SCX_ENQ_DSQ_PRIQ __SCX_ENQ_DSQ_PRIQ
+
diff --git a/tools/sched_ext/include/scx/enums.autogen.h b/tools/sched_ext/include/scx/enums.autogen.h
new file mode 100644
index 000000000000..88137a140e72
--- /dev/null
+++ b/tools/sched_ext/include/scx/enums.autogen.h
@@ -0,0 +1,41 @@
+/*
+ * WARNING: This file is autogenerated from scripts/gen_enums.py. If you would
+ * like to access an enum that is currently missing, add it to the script
+ * and run it from the root directory to update this file.
+ */
+
+#define SCX_ENUM_INIT(skel) do { \
+	SCX_ENUM_SET(skel, scx_public_consts, SCX_OPS_NAME_LEN); \
+	SCX_ENUM_SET(skel, scx_public_consts, SCX_SLICE_DFL); \
+	SCX_ENUM_SET(skel, scx_public_consts, SCX_SLICE_INF); \
+	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_FLAG_BUILTIN); \
+	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_FLAG_LOCAL_ON); \
+	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_INVALID); \
+	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_GLOBAL); \
+	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_LOCAL); \
+	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_LOCAL_ON); \
+	SCX_ENUM_SET(skel, scx_dsq_id_flags, SCX_DSQ_LOCAL_CPU_MASK); \
+	SCX_ENUM_SET(skel, scx_ent_flags, SCX_TASK_QUEUED); \
+	SCX_ENUM_SET(skel, scx_ent_flags, SCX_TASK_RESET_RUNNABLE_AT); \
+	SCX_ENUM_SET(skel, scx_ent_flags, SCX_TASK_DEQD_FOR_SLEEP); \
+	SCX_ENUM_SET(skel, scx_ent_flags, SCX_TASK_STATE_SHIFT); \
+	SCX_ENUM_SET(skel, scx_ent_flags, SCX_TASK_STATE_BITS); \
+	SCX_ENUM_SET(skel, scx_ent_flags, SCX_TASK_STATE_MASK); \
+	SCX_ENUM_SET(skel, scx_ent_flags, SCX_TASK_CURSOR); \
+	SCX_ENUM_SET(skel, scx_task_state, SCX_TASK_NONE); \
+	SCX_ENUM_SET(skel, scx_task_state, SCX_TASK_INIT); \
+	SCX_ENUM_SET(skel, scx_task_state, SCX_TASK_READY); \
+	SCX_ENUM_SET(skel, scx_task_state, SCX_TASK_ENABLED); \
+	SCX_ENUM_SET(skel, scx_task_state, SCX_TASK_NR_STATES); \
+	SCX_ENUM_SET(skel, scx_ent_dsq_flags, SCX_TASK_DSQ_ON_PRIQ); \
+	SCX_ENUM_SET(skel, scx_kick_flags, SCX_KICK_IDLE); \
+	SCX_ENUM_SET(skel, scx_kick_flags, SCX_KICK_PREEMPT); \
+	SCX_ENUM_SET(skel, scx_kick_flags, SCX_KICK_WAIT); \
+	SCX_ENUM_SET(skel, scx_enq_flags, SCX_ENQ_WAKEUP); \
+	SCX_ENUM_SET(skel, scx_enq_flags, SCX_ENQ_HEAD); \
+	SCX_ENUM_SET(skel, scx_enq_flags, SCX_ENQ_PREEMPT); \
+	SCX_ENUM_SET(skel, scx_enq_flags, SCX_ENQ_REENQ); \
+	SCX_ENUM_SET(skel, scx_enq_flags, SCX_ENQ_LAST); \
+	SCX_ENUM_SET(skel, scx_enq_flags, SCX_ENQ_CLEAR_OPSS); \
+	SCX_ENUM_SET(skel, scx_enq_flags, SCX_ENQ_DSQ_PRIQ); \
+} while (0)
diff --git a/tools/sched_ext/include/scx/enums.bpf.h b/tools/sched_ext/include/scx/enums.bpf.h
new file mode 100644
index 000000000000..af704c5d6334
--- /dev/null
+++ b/tools/sched_ext/include/scx/enums.bpf.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Convenience macros for getting/setting struct scx_enums instances.
+ *
+ * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
+ */
+#ifndef __SCX_ENUMS_BPF_H
+#define __SCX_ENUMS_BPF_H
+
+#include "enums.autogen.bpf.h"
+
+#endif /* __SCX_ENUMS_BPF_H */
diff --git a/tools/sched_ext/include/scx/enums.h b/tools/sched_ext/include/scx/enums.h
new file mode 100644
index 000000000000..34cbebe974b7
--- /dev/null
+++ b/tools/sched_ext/include/scx/enums.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Define struct scx_enums that stores the load-time values of enums
+ * used by the BPF program.
+ *
+ * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
+ */
+
+#ifndef __SCX_ENUMS_H
+#define __SCX_ENUMS_H
+
+static inline void __ENUM_set(u64 *val, char *type, char *name)
+{
+	bool res;
+
+	res = __COMPAT_read_enum(type, name, val);
+	SCX_BUG_ON(!res, "enum not found(%s)", name);
+}
+
+#define SCX_ENUM_SET(skel, type, name) do {			\
+	__ENUM_set(&skel->rodata->__##name, #type, #name);	\
+	} while (0)
+
+
+#include "enums.autogen.h"
+
+#endif /* __SCX_ENUMS_H */
diff --git a/tools/sched_ext/include/scx/user_exit_info.h b/tools/sched_ext/include/scx/user_exit_info.h
index 8ce2734402e1..66f856640ee7 100644
--- a/tools/sched_ext/include/scx/user_exit_info.h
+++ b/tools/sched_ext/include/scx/user_exit_info.h
@@ -10,6 +10,11 @@
 #ifndef __USER_EXIT_INFO_H
 #define __USER_EXIT_INFO_H
 
+#ifdef LSP
+#define __bpf__
+#include "../vmlinux.h"
+#endif
+
 enum uei_sizes {
 	UEI_REASON_LEN		= 128,
 	UEI_MSG_LEN		= 1024,
@@ -25,9 +30,7 @@ struct user_exit_info {
 
 #ifdef __bpf__
 
-#ifdef LSP
-#include "../vmlinux/vmlinux.h"
-#else
+#ifndef LSP
 #include "vmlinux.h"
 #endif
 #include <bpf/bpf_core_read.h>
diff --git a/tools/sched_ext/scx_central.bpf.c b/tools/sched_ext/scx_central.bpf.c
index e6fad6211f6c..50bc1737c167 100644
--- a/tools/sched_ext/scx_central.bpf.c
+++ b/tools/sched_ext/scx_central.bpf.c
@@ -57,7 +57,7 @@ enum {
 
 const volatile s32 central_cpu;
 const volatile u32 nr_cpu_ids = 1;	/* !0 for veristat, set during init */
-const volatile u64 slice_ns = SCX_SLICE_DFL;
+const volatile u64 slice_ns;
 
 bool timer_pinned = true;
 u64 nr_total, nr_locals, nr_queued, nr_lost_pids;
@@ -87,11 +87,6 @@ struct {
 	__type(value, struct central_timer);
 } central_timer SEC(".maps");
 
-static bool vtime_before(u64 a, u64 b)
-{
-	return (s64)(a - b) < 0;
-}
-
 s32 BPF_STRUCT_OPS(central_select_cpu, struct task_struct *p,
 		   s32 prev_cpu, u64 wake_flags)
 {
@@ -245,7 +240,7 @@ void BPF_STRUCT_OPS(central_running, struct task_struct *p)
 	s32 cpu = scx_bpf_task_cpu(p);
 	u64 *started_at = ARRAY_ELEM_PTR(cpu_started_at, cpu, nr_cpu_ids);
 	if (started_at)
-		*started_at = bpf_ktime_get_ns() ?: 1;	/* 0 indicates idle */
+		*started_at = scx_bpf_now() ?: 1;	/* 0 indicates idle */
 }
 
 void BPF_STRUCT_OPS(central_stopping, struct task_struct *p, bool runnable)
@@ -258,7 +253,7 @@ void BPF_STRUCT_OPS(central_stopping, struct task_struct *p, bool runnable)
 
 static int central_timerfn(void *map, int *key, struct bpf_timer *timer)
 {
-	u64 now = bpf_ktime_get_ns();
+	u64 now = scx_bpf_now();
 	u64 nr_to_kick = nr_queued;
 	s32 i, curr_cpu;
 
@@ -279,7 +274,7 @@ static int central_timerfn(void *map, int *key, struct bpf_timer *timer)
 		/* kick iff the current one exhausted its slice */
 		started_at = ARRAY_ELEM_PTR(cpu_started_at, cpu, nr_cpu_ids);
 		if (started_at && *started_at &&
-		    vtime_before(now, *started_at + slice_ns))
+		    time_before(now, *started_at + slice_ns))
 			continue;
 
 		/* and there's something pending */
diff --git a/tools/sched_ext/scx_central.c b/tools/sched_ext/scx_central.c
index e938156ed0a0..1e9f74525d8f 100644
--- a/tools/sched_ext/scx_central.c
+++ b/tools/sched_ext/scx_central.c
@@ -58,6 +58,7 @@ restart:
 
 	skel->rodata->central_cpu = 0;
 	skel->rodata->nr_cpu_ids = libbpf_num_possible_cpus();
+	skel->rodata->slice_ns = __COMPAT_ENUM_OR_ZERO("scx_public_consts", "SCX_SLICE_DFL");
 
 	while ((opt = getopt(argc, argv, "s:c:pvh")) != -1) {
 		switch (opt) {
diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
index 4e3afcd260bf..2c720e3ecad5 100644
--- a/tools/sched_ext/scx_flatcg.bpf.c
+++ b/tools/sched_ext/scx_flatcg.bpf.c
@@ -57,7 +57,7 @@ enum {
 char _license[] SEC("license") = "GPL";
 
 const volatile u32 nr_cpus = 32;	/* !0 for veristat, set during init */
-const volatile u64 cgrp_slice_ns = SCX_SLICE_DFL;
+const volatile u64 cgrp_slice_ns;
 const volatile bool fifo_sched;
 
 u64 cvtime_now;
@@ -137,11 +137,6 @@ static u64 div_round_up(u64 dividend, u64 divisor)
 	return (dividend + divisor - 1) / divisor;
 }
 
-static bool vtime_before(u64 a, u64 b)
-{
-	return (s64)(a - b) < 0;
-}
-
 static bool cgv_node_less(struct bpf_rb_node *a, const struct bpf_rb_node *b)
 {
 	struct cgv_node *cgc_a, *cgc_b;
@@ -271,7 +266,7 @@ static void cgrp_cap_budget(struct cgv_node *cgv_node, struct fcg_cgrp_ctx *cgc)
 	 */
 	max_budget = (cgrp_slice_ns * nr_cpus * cgc->hweight) /
 		(2 * FCG_HWEIGHT_ONE);
-	if (vtime_before(cvtime, cvtime_now - max_budget))
+	if (time_before(cvtime, cvtime_now - max_budget))
 		cvtime = cvtime_now - max_budget;
 
 	cgv_node->cvtime = cvtime;
@@ -401,7 +396,7 @@ void BPF_STRUCT_OPS(fcg_enqueue, struct task_struct *p, u64 enq_flags)
 		 * Limit the amount of budget that an idling task can accumulate
 		 * to one slice.
 		 */
-		if (vtime_before(tvtime, cgc->tvtime_now - SCX_SLICE_DFL))
+		if (time_before(tvtime, cgc->tvtime_now - SCX_SLICE_DFL))
 			tvtime = cgc->tvtime_now - SCX_SLICE_DFL;
 
 		scx_bpf_dsq_insert_vtime(p, cgrp->kn->id, SCX_SLICE_DFL,
@@ -535,7 +530,7 @@ void BPF_STRUCT_OPS(fcg_running, struct task_struct *p)
 		 * from multiple CPUs and thus racy. Any error should be
 		 * contained and temporary. Let's just live with it.
 		 */
-		if (vtime_before(cgc->tvtime_now, p->scx.dsq_vtime))
+		if (time_before(cgc->tvtime_now, p->scx.dsq_vtime))
 			cgc->tvtime_now = p->scx.dsq_vtime;
 	}
 	bpf_cgroup_release(cgrp);
@@ -645,7 +640,7 @@ static bool try_pick_next_cgroup(u64 *cgidp)
 	cgv_node = container_of(rb_node, struct cgv_node, rb_node);
 	cgid = cgv_node->cgid;
 
-	if (vtime_before(cvtime_now, cgv_node->cvtime))
+	if (time_before(cvtime_now, cgv_node->cvtime))
 		cvtime_now = cgv_node->cvtime;
 
 	/*
@@ -734,7 +729,7 @@ void BPF_STRUCT_OPS(fcg_dispatch, s32 cpu, struct task_struct *prev)
 	struct fcg_cpu_ctx *cpuc;
 	struct fcg_cgrp_ctx *cgc;
 	struct cgroup *cgrp;
-	u64 now = bpf_ktime_get_ns();
+	u64 now = scx_bpf_now();
 	bool picked_next = false;
 
 	cpuc = find_cpu_ctx();
@@ -744,7 +739,7 @@ void BPF_STRUCT_OPS(fcg_dispatch, s32 cpu, struct task_struct *prev)
 	if (!cpuc->cur_cgid)
 		goto pick_next_cgroup;
 
-	if (vtime_before(now, cpuc->cur_at + cgrp_slice_ns)) {
+	if (time_before(now, cpuc->cur_at + cgrp_slice_ns)) {
 		if (scx_bpf_dsq_move_to_local(cpuc->cur_cgid)) {
 			stat_inc(FCG_STAT_CNS_KEEP);
 			return;
@@ -920,14 +915,14 @@ void BPF_STRUCT_OPS(fcg_cgroup_move, struct task_struct *p,
 		    struct cgroup *from, struct cgroup *to)
 {
 	struct fcg_cgrp_ctx *from_cgc, *to_cgc;
-	s64 vtime_delta;
+	s64 delta;
 
 	/* find_cgrp_ctx() triggers scx_ops_error() on lookup failures */
 	if (!(from_cgc = find_cgrp_ctx(from)) || !(to_cgc = find_cgrp_ctx(to)))
 		return;
 
-	vtime_delta = p->scx.dsq_vtime - from_cgc->tvtime_now;
-	p->scx.dsq_vtime = to_cgc->tvtime_now + vtime_delta;
+	delta = time_delta(p->scx.dsq_vtime, from_cgc->tvtime_now);
+	p->scx.dsq_vtime = to_cgc->tvtime_now + delta;
 }
 
 s32 BPF_STRUCT_OPS_SLEEPABLE(fcg_init)
diff --git a/tools/sched_ext/scx_flatcg.c b/tools/sched_ext/scx_flatcg.c
index 5d24ca9c29d9..6dd423eeb4ff 100644
--- a/tools/sched_ext/scx_flatcg.c
+++ b/tools/sched_ext/scx_flatcg.c
@@ -137,6 +137,7 @@ restart:
 	skel = SCX_OPS_OPEN(flatcg_ops, scx_flatcg);
 
 	skel->rodata->nr_cpus = libbpf_num_possible_cpus();
+	skel->rodata->cgrp_slice_ns = __COMPAT_ENUM_OR_ZERO("scx_public_consts", "SCX_SLICE_DFL");
 
 	while ((opt = getopt(argc, argv, "s:i:dfvh")) != -1) {
 		double v;
diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c
index ee264947e0c3..3a20bb0c014a 100644
--- a/tools/sched_ext/scx_qmap.bpf.c
+++ b/tools/sched_ext/scx_qmap.bpf.c
@@ -33,7 +33,7 @@ enum consts {
 
 char _license[] SEC("license") = "GPL";
 
-const volatile u64 slice_ns = SCX_SLICE_DFL;
+const volatile u64 slice_ns;
 const volatile u32 stall_user_nth;
 const volatile u32 stall_kernel_nth;
 const volatile u32 dsp_inf_loop_after;
diff --git a/tools/sched_ext/scx_qmap.c b/tools/sched_ext/scx_qmap.c
index ac45a02b4055..c4912ab2e76f 100644
--- a/tools/sched_ext/scx_qmap.c
+++ b/tools/sched_ext/scx_qmap.c
@@ -64,6 +64,8 @@ int main(int argc, char **argv)
 
 	skel = SCX_OPS_OPEN(qmap_ops, scx_qmap);
 
+	skel->rodata->slice_ns = __COMPAT_ENUM_OR_ZERO("scx_public_consts", "SCX_SLICE_DFL");
+
 	while ((opt = getopt(argc, argv, "s:e:t:T:l:b:PHd:D:Spvh")) != -1) {
 		switch (opt) {
 		case 's':
diff --git a/tools/sched_ext/scx_simple.bpf.c b/tools/sched_ext/scx_simple.bpf.c
index 31f915b286c6..e6de99dba7db 100644
--- a/tools/sched_ext/scx_simple.bpf.c
+++ b/tools/sched_ext/scx_simple.bpf.c
@@ -52,11 +52,6 @@ static void stat_inc(u32 idx)
 		(*cnt_p)++;
 }
 
-static inline bool vtime_before(u64 a, u64 b)
-{
-	return (s64)(a - b) < 0;
-}
-
 s32 BPF_STRUCT_OPS(simple_select_cpu, struct task_struct *p, s32 prev_cpu, u64 wake_flags)
 {
 	bool is_idle = false;
@@ -84,7 +79,7 @@ void BPF_STRUCT_OPS(simple_enqueue, struct task_struct *p, u64 enq_flags)
 		 * Limit the amount of budget that an idling task can accumulate
 		 * to one slice.
 		 */
-		if (vtime_before(vtime, vtime_now - SCX_SLICE_DFL))
+		if (time_before(vtime, vtime_now - SCX_SLICE_DFL))
 			vtime = vtime_now - SCX_SLICE_DFL;
 
 		scx_bpf_dsq_insert_vtime(p, SHARED_DSQ, SCX_SLICE_DFL, vtime,
@@ -108,7 +103,7 @@ void BPF_STRUCT_OPS(simple_running, struct task_struct *p)
 	 * thus racy. Any error should be contained and temporary. Let's just
 	 * live with it.
 	 */
-	if (vtime_before(vtime_now, p->scx.dsq_vtime))
+	if (time_before(vtime_now, p->scx.dsq_vtime))
 		vtime_now = p->scx.dsq_vtime;
 }
 
diff --git a/tools/testing/selftests/sched_ext/runner.c b/tools/testing/selftests/sched_ext/runner.c
index eab48c7ff309..aa2d7d32dda9 100644
--- a/tools/testing/selftests/sched_ext/runner.c
+++ b/tools/testing/selftests/sched_ext/runner.c
@@ -22,11 +22,12 @@ const char help_fmt[] =
 "\n"
 "  -t TEST       Only run tests whose name includes this string\n"
 "  -s            Include print output for skipped tests\n"
+"  -l            List all available tests\n"
 "  -q            Don't print the test descriptions during run\n"
 "  -h            Display this help and exit\n";
 
 static volatile int exit_req;
-static bool quiet, print_skipped;
+static bool quiet, print_skipped, list;
 
 #define MAX_SCX_TESTS 2048
 
@@ -133,7 +134,7 @@ int main(int argc, char **argv)
 
 	libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
 
-	while ((opt = getopt(argc, argv, "qst:h")) != -1) {
+	while ((opt = getopt(argc, argv, "qslt:h")) != -1) {
 		switch (opt) {
 		case 'q':
 			quiet = true;
@@ -141,6 +142,9 @@ int main(int argc, char **argv)
 		case 's':
 			print_skipped = true;
 			break;
+		case 'l':
+			list = true;
+			break;
 		case 't':
 			filter = optarg;
 			break;
@@ -154,6 +158,13 @@ int main(int argc, char **argv)
 		enum scx_test_status status;
 		struct scx_test *test = &__scx_tests[i];
 
+		if (list) {
+			printf("%s\n", test->name);
+			if (i == (__scx_num_tests - 1))
+				return 0;
+			continue;
+		}
+
 		if (filter && should_skip_test(test, filter)) {
 			/*
 			 * Printing the skipped tests and their preambles can