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

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 */

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 */

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().

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; 								\
 })
 

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
+

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)

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 */

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 */

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>

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 */

tools/sched_ext/scx_central.c

@@ -58,6 +58,7 @@ int main(int argc, char **argv)
 
 	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) {

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)

tools/sched_ext/scx_flatcg.c

@@ -137,6 +137,7 @@ int main(int argc, char **argv)
 	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;

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;

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':

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;
 }
 

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