diff options
| -rw-r--r-- | kernel/sched/ext.c | 320 | ||||
| -rw-r--r-- | tools/sched_ext/include/scx/common.bpf.h | 15 | ||||
| -rw-r--r-- | tools/sched_ext/include/scx/compat.bpf.h | 19 | ||||
| -rw-r--r-- | tools/sched_ext/include/scx/user_exit_info.h | 4 | ||||
| -rw-r--r-- | tools/sched_ext/scx_flatcg.bpf.c | 32 | ||||
| -rw-r--r-- | tools/sched_ext/scx_qmap.bpf.c | 12 |
6 files changed, 236 insertions, 166 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index c09e3dc38c34..3cd7c50a51c5 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -9,6 +9,7 @@ #define SCX_OP_IDX(op) (offsetof(struct sched_ext_ops, op) / sizeof(void (*)(void))) enum scx_consts { + SCX_SLICE_BYPASS = SCX_SLICE_DFL / 4, SCX_DSP_DFL_MAX_BATCH = 32, SCX_DSP_MAX_LOOPS = 32, SCX_WATCHDOG_MAX_TIMEOUT = 30 * HZ, @@ -778,7 +779,6 @@ enum scx_tg_flags { }; enum scx_ops_enable_state { - SCX_OPS_PREPPING, SCX_OPS_ENABLING, SCX_OPS_ENABLED, SCX_OPS_DISABLING, @@ -786,7 +786,6 @@ enum scx_ops_enable_state { }; static const char *scx_ops_enable_state_str[] = { - [SCX_OPS_PREPPING] = "prepping", [SCX_OPS_ENABLING] = "enabling", [SCX_OPS_ENABLED] = "enabled", [SCX_OPS_DISABLING] = "disabling", @@ -854,6 +853,7 @@ DEFINE_STATIC_KEY_FALSE(__scx_ops_enabled); DEFINE_STATIC_PERCPU_RWSEM(scx_fork_rwsem); static atomic_t scx_ops_enable_state_var = ATOMIC_INIT(SCX_OPS_DISABLED); static atomic_t scx_ops_bypass_depth = ATOMIC_INIT(0); +static bool scx_ops_init_task_enabled; static bool scx_switching_all; DEFINE_STATIC_KEY_FALSE(__scx_switched_all); @@ -925,8 +925,15 @@ static unsigned long __percpu *scx_kick_cpus_pnt_seqs; */ static DEFINE_PER_CPU(struct task_struct *, direct_dispatch_task); -/* dispatch queues */ -static struct scx_dispatch_q __cacheline_aligned_in_smp scx_dsq_global; +/* + * Dispatch queues. + * + * The global DSQ (%SCX_DSQ_GLOBAL) is split per-node for scalability. This is + * to avoid live-locking in bypass mode where all tasks are dispatched to + * %SCX_DSQ_GLOBAL and all CPUs consume from it. If per-node split isn't + * sufficient, it can be further split. + */ +static struct scx_dispatch_q **global_dsqs; static const struct rhashtable_params dsq_hash_params = { .key_len = 8, @@ -1029,6 +1036,16 @@ static bool u32_before(u32 a, u32 b) return (s32)(a - b) < 0; } +static struct scx_dispatch_q *find_global_dsq(struct task_struct *p) +{ + return global_dsqs[cpu_to_node(task_cpu(p))]; +} + +static struct scx_dispatch_q *find_user_dsq(u64 dsq_id) +{ + return rhashtable_lookup_fast(&dsq_hash, &dsq_id, dsq_hash_params); +} + /* * scx_kf_mask enforcement. Some kfuncs can only be called from specific SCX * ops. When invoking SCX ops, SCX_CALL_OP[_RET]() should be used to indicate @@ -1637,7 +1654,7 @@ static void dispatch_enqueue(struct scx_dispatch_q *dsq, struct task_struct *p, scx_ops_error("attempting to dispatch to a destroyed dsq"); /* fall back to the global dsq */ raw_spin_unlock(&dsq->lock); - dsq = &scx_dsq_global; + dsq = find_global_dsq(p); raw_spin_lock(&dsq->lock); } } @@ -1803,21 +1820,6 @@ static void dispatch_dequeue(struct rq *rq, struct task_struct *p) raw_spin_unlock(&dsq->lock); } -static struct scx_dispatch_q *find_user_dsq(u64 dsq_id) -{ - return rhashtable_lookup_fast(&dsq_hash, &dsq_id, dsq_hash_params); -} - -static struct scx_dispatch_q *find_non_local_dsq(u64 dsq_id) -{ - lockdep_assert(rcu_read_lock_any_held()); - - if (dsq_id == SCX_DSQ_GLOBAL) - return &scx_dsq_global; - else - return find_user_dsq(dsq_id); -} - static struct scx_dispatch_q *find_dsq_for_dispatch(struct rq *rq, u64 dsq_id, struct task_struct *p) { @@ -1830,16 +1832,20 @@ static struct scx_dispatch_q *find_dsq_for_dispatch(struct rq *rq, u64 dsq_id, s32 cpu = dsq_id & SCX_DSQ_LOCAL_CPU_MASK; if (!ops_cpu_valid(cpu, "in SCX_DSQ_LOCAL_ON dispatch verdict")) - return &scx_dsq_global; + return find_global_dsq(p); return &cpu_rq(cpu)->scx.local_dsq; } - dsq = find_non_local_dsq(dsq_id); + if (dsq_id == SCX_DSQ_GLOBAL) + dsq = find_global_dsq(p); + else + dsq = find_user_dsq(dsq_id); + if (unlikely(!dsq)) { scx_ops_error("non-existent DSQ 0x%llx for %s[%d]", dsq_id, p->comm, p->pid); - return &scx_dsq_global; + return find_global_dsq(p); } return dsq; @@ -1938,6 +1944,7 @@ static bool scx_rq_online(struct rq *rq) static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags, int sticky_cpu) { + bool bypassing = scx_rq_bypassing(rq); struct task_struct **ddsp_taskp; unsigned long qseq; @@ -1955,7 +1962,7 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags, if (!scx_rq_online(rq)) goto local; - if (scx_rq_bypassing(rq)) + if (bypassing) goto global; if (p->scx.ddsp_dsq_id != SCX_DSQ_INVALID) @@ -2010,8 +2017,8 @@ local_norefill: global: touch_core_sched(rq, p); /* see the comment in local: */ - p->scx.slice = SCX_SLICE_DFL; - dispatch_enqueue(&scx_dsq_global, p, enq_flags); + p->scx.slice = bypassing ? SCX_SLICE_BYPASS : SCX_SLICE_DFL; + dispatch_enqueue(find_global_dsq(p), p, enq_flags); } static bool task_runnable(const struct task_struct *p) @@ -2357,6 +2364,7 @@ static bool consume_remote_task(struct rq *this_rq, struct task_struct *p, } } #else /* CONFIG_SMP */ +static inline void move_remote_task_to_local_dsq(struct task_struct *p, u64 enq_flags, struct rq *src_rq, struct rq *dst_rq) { WARN_ON_ONCE(1); } static inline bool task_can_run_on_remote_rq(struct task_struct *p, struct rq *rq, bool trigger_error) { return false; } static inline bool consume_remote_task(struct rq *this_rq, struct task_struct *p, struct scx_dispatch_q *dsq, struct rq *task_rq) { return false; } #endif /* CONFIG_SMP */ @@ -2396,6 +2404,13 @@ retry: return false; } +static bool consume_global_dsq(struct rq *rq) +{ + int node = cpu_to_node(cpu_of(rq)); + + return consume_dispatch_q(rq, global_dsqs[node]); +} + /** * dispatch_to_local_dsq - Dispatch a task to a local dsq * @rq: current rq which is locked @@ -2429,7 +2444,8 @@ static void dispatch_to_local_dsq(struct rq *rq, struct scx_dispatch_q *dst_dsq, #ifdef CONFIG_SMP if (unlikely(!task_can_run_on_remote_rq(p, dst_rq, true))) { - dispatch_enqueue(&scx_dsq_global, p, enq_flags | SCX_ENQ_CLEAR_OPSS); + dispatch_enqueue(find_global_dsq(p), p, + enq_flags | SCX_ENQ_CLEAR_OPSS); return; } @@ -2629,7 +2645,7 @@ static int balance_one(struct rq *rq, struct task_struct *prev) if (rq->scx.local_dsq.nr) goto has_tasks; - if (consume_dispatch_q(rq, &scx_dsq_global)) + if (consume_global_dsq(rq)) goto has_tasks; if (!SCX_HAS_OP(dispatch) || scx_rq_bypassing(rq) || !scx_rq_online(rq)) @@ -2654,7 +2670,7 @@ static int balance_one(struct rq *rq, struct task_struct *prev) if (rq->scx.local_dsq.nr) goto has_tasks; - if (consume_dispatch_q(rq, &scx_dsq_global)) + if (consume_global_dsq(rq)) goto has_tasks; /* @@ -3058,22 +3074,13 @@ static s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, * there is an idle core elsewhere on the system. */ cpu = smp_processor_id(); - if ((wake_flags & SCX_WAKE_SYNC) && p->nr_cpus_allowed > 1 && + if ((wake_flags & SCX_WAKE_SYNC) && !cpumask_empty(idle_masks.cpu) && !(current->flags & PF_EXITING) && cpu_rq(cpu)->scx.local_dsq.nr == 0) { if (cpumask_test_cpu(cpu, p->cpus_ptr)) goto cpu_found; } - if (p->nr_cpus_allowed == 1) { - if (test_and_clear_cpu_idle(prev_cpu)) { - cpu = prev_cpu; - goto cpu_found; - } else { - return prev_cpu; - } - } - /* * If CPU has SMT, any wholly idle CPU is likely a better pick than * partially idle @prev_cpu. @@ -3550,7 +3557,7 @@ int scx_fork(struct task_struct *p) { percpu_rwsem_assert_held(&scx_fork_rwsem); - if (scx_enabled()) + if (scx_ops_init_task_enabled) return scx_ops_init_task(p, task_group(p), true); else return 0; @@ -3558,7 +3565,7 @@ int scx_fork(struct task_struct *p) void scx_post_fork(struct task_struct *p) { - if (scx_enabled()) { + if (scx_ops_init_task_enabled) { scx_set_task_state(p, SCX_TASK_READY); /* @@ -3690,6 +3697,7 @@ bool scx_can_stop_tick(struct rq *rq) #ifdef CONFIG_EXT_GROUP_SCHED DEFINE_STATIC_PERCPU_RWSEM(scx_cgroup_rwsem); +static bool scx_cgroup_enabled; static bool cgroup_warned_missing_weight; static bool cgroup_warned_missing_idle; @@ -3709,8 +3717,7 @@ static void scx_cgroup_warn_missing_weight(struct task_group *tg) static void scx_cgroup_warn_missing_idle(struct task_group *tg) { - if (scx_ops_enable_state() == SCX_OPS_DISABLED || - cgroup_warned_missing_idle) + if (!scx_cgroup_enabled || cgroup_warned_missing_idle) return; if (!tg->idle) @@ -3731,15 +3738,18 @@ int scx_tg_online(struct task_group *tg) scx_cgroup_warn_missing_weight(tg); - if (SCX_HAS_OP(cgroup_init)) { - struct scx_cgroup_init_args args = { .weight = tg->scx_weight }; + if (scx_cgroup_enabled) { + if (SCX_HAS_OP(cgroup_init)) { + struct scx_cgroup_init_args args = + { .weight = tg->scx_weight }; - ret = SCX_CALL_OP_RET(SCX_KF_UNLOCKED, cgroup_init, - tg->css.cgroup, &args); - if (!ret) + ret = SCX_CALL_OP_RET(SCX_KF_UNLOCKED, cgroup_init, + tg->css.cgroup, &args); + if (ret) + ret = ops_sanitize_err("cgroup_init", ret); + } + if (ret == 0) tg->scx_flags |= SCX_TG_ONLINE | SCX_TG_INITED; - else - ret = ops_sanitize_err("cgroup_init", ret); } else { tg->scx_flags |= SCX_TG_ONLINE; } @@ -3770,7 +3780,7 @@ int scx_cgroup_can_attach(struct cgroup_taskset *tset) /* released in scx_finish/cancel_attach() */ percpu_down_read(&scx_cgroup_rwsem); - if (!scx_enabled()) + if (!scx_cgroup_enabled) return 0; cgroup_taskset_for_each(p, css, tset) { @@ -3813,7 +3823,7 @@ err: void scx_move_task(struct task_struct *p) { - if (!scx_enabled()) + if (!scx_cgroup_enabled) return; /* @@ -3849,7 +3859,7 @@ void scx_cgroup_cancel_attach(struct cgroup_taskset *tset) struct cgroup_subsys_state *css; struct task_struct *p; - if (!scx_enabled()) + if (!scx_cgroup_enabled) goto out_unlock; cgroup_taskset_for_each(p, css, tset) { @@ -3866,7 +3876,7 @@ void scx_group_set_weight(struct task_group *tg, unsigned long weight) { percpu_down_read(&scx_cgroup_rwsem); - if (tg->scx_weight != weight) { + if (scx_cgroup_enabled && tg->scx_weight != weight) { if (SCX_HAS_OP(cgroup_set_weight)) SCX_CALL_OP(SCX_KF_UNLOCKED, cgroup_set_weight, tg_cgrp(tg), weight); @@ -4038,6 +4048,9 @@ static void scx_cgroup_exit(void) percpu_rwsem_assert_held(&scx_cgroup_rwsem); + WARN_ON_ONCE(!scx_cgroup_enabled); + scx_cgroup_enabled = false; + /* * scx_tg_on/offline() are excluded through scx_cgroup_rwsem. If we walk * cgroups and exit all the inited ones, all online cgroups are exited. @@ -4113,6 +4126,9 @@ static int scx_cgroup_init(void) } rcu_read_unlock(); + WARN_ON_ONCE(scx_cgroup_enabled); + scx_cgroup_enabled = true; + return 0; } @@ -4431,19 +4447,23 @@ static void scx_ops_disable_workfn(struct kthread_work *work) WRITE_ONCE(scx_switching_all, false); /* - * Avoid racing against fork and cgroup changes. See scx_ops_enable() - * for explanation on the locking order. + * Shut down cgroup support before tasks so that the cgroup attach path + * doesn't race against scx_ops_exit_task(). */ - percpu_down_write(&scx_fork_rwsem); - cpus_read_lock(); scx_cgroup_lock(); + scx_cgroup_exit(); + scx_cgroup_unlock(); - spin_lock_irq(&scx_tasks_lock); - scx_task_iter_init(&sti); /* * The BPF scheduler is going away. All tasks including %TASK_DEAD ones * must be switched out and exited synchronously. */ + percpu_down_write(&scx_fork_rwsem); + + scx_ops_init_task_enabled = false; + + spin_lock_irq(&scx_tasks_lock); + scx_task_iter_init(&sti); while ((p = scx_task_iter_next_locked(&sti))) { const struct sched_class *old_class = p->sched_class; struct sched_enq_and_set_ctx ctx; @@ -4461,23 +4481,18 @@ static void scx_ops_disable_workfn(struct kthread_work *work) } scx_task_iter_exit(&sti); spin_unlock_irq(&scx_tasks_lock); + percpu_up_write(&scx_fork_rwsem); /* no task is on scx, turn off all the switches and flush in-progress calls */ - static_branch_disable_cpuslocked(&__scx_ops_enabled); + static_branch_disable(&__scx_ops_enabled); for (i = SCX_OPI_BEGIN; i < SCX_OPI_END; i++) - static_branch_disable_cpuslocked(&scx_has_op[i]); - static_branch_disable_cpuslocked(&scx_ops_enq_last); - static_branch_disable_cpuslocked(&scx_ops_enq_exiting); - static_branch_disable_cpuslocked(&scx_ops_cpu_preempt); - static_branch_disable_cpuslocked(&scx_builtin_idle_enabled); + static_branch_disable(&scx_has_op[i]); + static_branch_disable(&scx_ops_enq_last); + static_branch_disable(&scx_ops_enq_exiting); + static_branch_disable(&scx_ops_cpu_preempt); + static_branch_disable(&scx_builtin_idle_enabled); synchronize_rcu(); - scx_cgroup_exit(); - - scx_cgroup_unlock(); - cpus_read_unlock(); - percpu_up_write(&scx_fork_rwsem); - if (ei->kind >= SCX_EXIT_ERROR) { pr_err("sched_ext: BPF scheduler \"%s\" disabled (%s)\n", scx_ops.name, ei->reason); @@ -4929,7 +4944,7 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) struct scx_task_iter sti; struct task_struct *p; unsigned long timeout; - int i, cpu, ret; + int i, cpu, node, ret; if (!cpumask_equal(housekeeping_cpumask(HK_TYPE_DOMAIN), cpu_possible_mask)) { @@ -4948,6 +4963,34 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) } } + if (!global_dsqs) { + struct scx_dispatch_q **dsqs; + + dsqs = kcalloc(nr_node_ids, sizeof(dsqs[0]), GFP_KERNEL); + if (!dsqs) { + ret = -ENOMEM; + goto err_unlock; + } + + for_each_node_state(node, N_POSSIBLE) { + struct scx_dispatch_q *dsq; + + dsq = kzalloc_node(sizeof(*dsq), GFP_KERNEL, node); + if (!dsq) { + for_each_node_state(node, N_POSSIBLE) + kfree(dsqs[node]); + kfree(dsqs); + ret = -ENOMEM; + goto err_unlock; + } + + init_dsq(dsq, SCX_DSQ_GLOBAL); + dsqs[node] = dsq; + } + + global_dsqs = dsqs; + } + if (scx_ops_enable_state() != SCX_OPS_DISABLED) { ret = -EBUSY; goto err_unlock; @@ -4971,12 +5014,12 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) } /* - * Set scx_ops, transition to PREPPING and clear exit info to arm the + * Set scx_ops, transition to ENABLING and clear exit info to arm the * disable path. Failure triggers full disabling from here on. */ scx_ops = *ops; - WARN_ON_ONCE(scx_ops_set_enable_state(SCX_OPS_PREPPING) != + WARN_ON_ONCE(scx_ops_set_enable_state(SCX_OPS_ENABLING) != SCX_OPS_DISABLED); atomic_set(&scx_exit_kind, SCX_EXIT_NONE); @@ -4997,7 +5040,8 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) ret = SCX_CALL_OP_RET(SCX_KF_UNLOCKED, init); if (ret) { ret = ops_sanitize_err("init", ret); - goto err_disable_unlock_cpus; + cpus_read_unlock(); + goto err_disable; } } @@ -5005,6 +5049,7 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) if (((void (**)(void))ops)[i]) static_branch_enable_cpuslocked(&scx_has_op[i]); + check_hotplug_seq(ops); cpus_read_unlock(); ret = validate_ops(ops); @@ -5032,57 +5077,40 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) scx_watchdog_timeout / 2); /* - * Lock out forks, cgroup on/offlining and moves before opening the - * floodgate so that they don't wander into the operations prematurely. - * - * We don't need to keep the CPUs stable but static_branch_*() requires - * cpus_read_lock() and scx_cgroup_rwsem must nest inside - * cpu_hotplug_lock because of the following dependency chain: - * - * cpu_hotplug_lock --> cgroup_threadgroup_rwsem --> scx_cgroup_rwsem - * - * So, we need to do cpus_read_lock() before scx_cgroup_lock() and use - * static_branch_*_cpuslocked(). - * - * Note that cpu_hotplug_lock must nest inside scx_fork_rwsem due to the - * following dependency chain: - * - * scx_fork_rwsem --> pernet_ops_rwsem --> cpu_hotplug_lock + * Once __scx_ops_enabled is set, %current can be switched to SCX + * anytime. This can lead to stalls as some BPF schedulers (e.g. + * userspace scheduling) may not function correctly before all tasks are + * switched. Init in bypass mode to guarantee forward progress. */ - percpu_down_write(&scx_fork_rwsem); - cpus_read_lock(); - scx_cgroup_lock(); - - check_hotplug_seq(ops); + scx_ops_bypass(true); for (i = SCX_OPI_NORMAL_BEGIN; i < SCX_OPI_NORMAL_END; i++) if (((void (**)(void))ops)[i]) - static_branch_enable_cpuslocked(&scx_has_op[i]); + static_branch_enable(&scx_has_op[i]); if (ops->flags & SCX_OPS_ENQ_LAST) - static_branch_enable_cpuslocked(&scx_ops_enq_last); + static_branch_enable(&scx_ops_enq_last); if (ops->flags & SCX_OPS_ENQ_EXITING) - static_branch_enable_cpuslocked(&scx_ops_enq_exiting); + static_branch_enable(&scx_ops_enq_exiting); if (scx_ops.cpu_acquire || scx_ops.cpu_release) - static_branch_enable_cpuslocked(&scx_ops_cpu_preempt); + static_branch_enable(&scx_ops_cpu_preempt); if (!ops->update_idle || (ops->flags & SCX_OPS_KEEP_BUILTIN_IDLE)) { reset_idle_masks(); - static_branch_enable_cpuslocked(&scx_builtin_idle_enabled); + static_branch_enable(&scx_builtin_idle_enabled); } else { - static_branch_disable_cpuslocked(&scx_builtin_idle_enabled); + static_branch_disable(&scx_builtin_idle_enabled); } /* - * All cgroups should be initialized before letting in tasks. cgroup - * on/offlining and task migrations are already locked out. + * Lock out forks, cgroup on/offlining and moves before opening the + * floodgate so that they don't wander into the operations prematurely. */ - ret = scx_cgroup_init(); - if (ret) - goto err_disable_unlock_all; + percpu_down_write(&scx_fork_rwsem); - static_branch_enable_cpuslocked(&__scx_ops_enabled); + WARN_ON_ONCE(scx_ops_init_task_enabled); + scx_ops_init_task_enabled = true; /* * Enable ops for every task. Fork is excluded by scx_fork_rwsem @@ -5090,9 +5118,19 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) * leaving as sched_ext_free() can handle both prepped and enabled * tasks. Prep all tasks first and then enable them with preemption * disabled. + * + * All cgroups should be initialized before scx_ops_init_task() so that + * the BPF scheduler can reliably track each task's cgroup membership + * from scx_ops_init_task(). Lock out cgroup on/offlining and task + * migrations while tasks are being initialized so that + * scx_cgroup_can_attach() never sees uninitialized tasks. */ - spin_lock_irq(&scx_tasks_lock); + scx_cgroup_lock(); + ret = scx_cgroup_init(); + if (ret) + goto err_disable_unlock_all; + spin_lock_irq(&scx_tasks_lock); scx_task_iter_init(&sti); while ((p = scx_task_iter_next_locked(&sti))) { /* @@ -5117,43 +5155,30 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) goto err_disable_unlock_all; } + scx_set_task_state(p, SCX_TASK_READY); + put_task_struct(p); spin_lock_irq(&scx_tasks_lock); } scx_task_iter_exit(&sti); + spin_unlock_irq(&scx_tasks_lock); + scx_cgroup_unlock(); + percpu_up_write(&scx_fork_rwsem); /* - * All tasks are prepped but are still ops-disabled. Ensure that - * %current can't be scheduled out and switch everyone. - * preempt_disable() is necessary because we can't guarantee that - * %current won't be starved if scheduled out while switching. - */ - preempt_disable(); - - /* - * From here on, the disable path must assume that tasks have ops - * enabled and need to be recovered. - * - * Transition to ENABLING fails iff the BPF scheduler has already - * triggered scx_bpf_error(). Returning an error code here would lose - * the recorded error information. Exit indicating success so that the - * error is notified through ops.exit() with all the details. + * All tasks are READY. It's safe to turn on scx_enabled() and switch + * all eligible tasks. */ - if (!scx_ops_tryset_enable_state(SCX_OPS_ENABLING, SCX_OPS_PREPPING)) { - preempt_enable(); - spin_unlock_irq(&scx_tasks_lock); - WARN_ON_ONCE(atomic_read(&scx_exit_kind) == SCX_EXIT_NONE); - ret = 0; - goto err_disable_unlock_all; - } + WRITE_ONCE(scx_switching_all, !(ops->flags & SCX_OPS_SWITCH_PARTIAL)); + static_branch_enable(&__scx_ops_enabled); /* - * We're fully committed and can't fail. The PREPPED -> ENABLED + * We're fully committed and can't fail. The task READY -> ENABLED * transitions here are synchronized against sched_ext_free() through * scx_tasks_lock. */ - WRITE_ONCE(scx_switching_all, !(ops->flags & SCX_OPS_SWITCH_PARTIAL)); - + percpu_down_write(&scx_fork_rwsem); + spin_lock_irq(&scx_tasks_lock); scx_task_iter_init(&sti); while ((p = scx_task_iter_next_locked(&sti))) { const struct sched_class *old_class = p->sched_class; @@ -5161,7 +5186,6 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) sched_deq_and_put_task(p, DEQUEUE_SAVE | DEQUEUE_MOVE, &ctx); - scx_set_task_state(p, SCX_TASK_READY); __setscheduler_prio(p, p->prio); check_class_changing(task_rq(p), p, old_class); @@ -5170,14 +5194,16 @@ static int scx_ops_enable(struct sched_ext_ops *ops, struct bpf_link *link) check_class_changed(task_rq(p), p, old_class, p->prio); } scx_task_iter_exit(&sti); - spin_unlock_irq(&scx_tasks_lock); - preempt_enable(); - scx_cgroup_unlock(); - cpus_read_unlock(); percpu_up_write(&scx_fork_rwsem); - /* see above ENABLING transition for the explanation on exiting with 0 */ + scx_ops_bypass(false); + + /* + * Returning an error code here would lose the recorded error + * information. Exit indicating success so that the error is notified + * through ops.exit() with all the details. + */ if (!scx_ops_tryset_enable_state(SCX_OPS_ENABLED, SCX_OPS_ENABLING)) { WARN_ON_ONCE(atomic_read(&scx_exit_kind) == SCX_EXIT_NONE); ret = 0; @@ -5212,8 +5238,7 @@ err_unlock: err_disable_unlock_all: scx_cgroup_unlock(); percpu_up_write(&scx_fork_rwsem); -err_disable_unlock_cpus: - cpus_read_unlock(); + scx_ops_bypass(false); err_disable: mutex_unlock(&scx_ops_enable_mutex); /* must be fully disabled before returning */ @@ -5782,7 +5807,6 @@ void __init init_sched_ext_class(void) SCX_TG_ONLINE); BUG_ON(rhashtable_init(&dsq_hash, &dsq_hash_params)); - init_dsq(&scx_dsq_global, SCX_DSQ_GLOBAL); #ifdef CONFIG_SMP BUG_ON(!alloc_cpumask_var(&idle_masks.cpu, GFP_KERNEL)); BUG_ON(!alloc_cpumask_var(&idle_masks.smt, GFP_KERNEL)); @@ -6058,7 +6082,7 @@ static bool scx_dispatch_from_dsq(struct bpf_iter_scx_dsq_kern *kit, if (dst_dsq->id == SCX_DSQ_LOCAL) { dst_rq = container_of(dst_dsq, struct rq, scx.local_dsq); if (!task_can_run_on_remote_rq(p, dst_rq, true)) { - dst_dsq = &scx_dsq_global; + dst_dsq = find_global_dsq(p); dst_rq = src_rq; } } else { @@ -6175,7 +6199,7 @@ __bpf_kfunc bool scx_bpf_consume(u64 dsq_id) flush_dispatch_buf(dspc->rq); - dsq = find_non_local_dsq(dsq_id); + dsq = find_user_dsq(dsq_id); if (unlikely(!dsq)) { scx_ops_error("invalid DSQ ID 0x%016llx", dsq_id); return false; @@ -6496,7 +6520,7 @@ __bpf_kfunc s32 scx_bpf_dsq_nr_queued(u64 dsq_id) goto out; } } else { - dsq = find_non_local_dsq(dsq_id); + dsq = find_user_dsq(dsq_id); if (dsq) { ret = READ_ONCE(dsq->nr); goto out; @@ -6545,7 +6569,7 @@ __bpf_kfunc int bpf_iter_scx_dsq_new(struct bpf_iter_scx_dsq *it, u64 dsq_id, if (flags & ~__SCX_DSQ_ITER_USER_FLAGS) return -EINVAL; - kit->dsq = find_non_local_dsq(dsq_id); + kit->dsq = find_user_dsq(dsq_id); if (!kit->dsq) return -ENOENT; diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h index f538c75db183..225f61f9bfca 100644 --- a/tools/sched_ext/include/scx/common.bpf.h +++ b/tools/sched_ext/include/scx/common.bpf.h @@ -7,7 +7,13 @@ #ifndef __SCX_COMMON_BPF_H #define __SCX_COMMON_BPF_H +#ifdef LSP +#define __bpf__ +#include "../vmlinux/vmlinux.h" +#else #include "vmlinux.h" +#endif + #include <bpf/bpf_helpers.h> #include <bpf/bpf_tracing.h> #include <asm-generic/errno.h> @@ -309,6 +315,15 @@ void bpf_cpumask_copy(struct bpf_cpumask *dst, const struct cpumask *src) __ksym u32 bpf_cpumask_any_distribute(const struct cpumask *cpumask) __ksym; u32 bpf_cpumask_any_and_distribute(const struct cpumask *src1, const struct cpumask *src2) __ksym; +u32 bpf_cpumask_weight(const struct cpumask *cpumask) __ksym; + +/* + * Access a cpumask in read-only mode (typically to check bits). + */ +const struct cpumask *cast_mask(struct bpf_cpumask *mask) +{ + return (const struct cpumask *)mask; +} /* rcu */ void bpf_rcu_read_lock(void) __ksym; diff --git a/tools/sched_ext/include/scx/compat.bpf.h b/tools/sched_ext/include/scx/compat.bpf.h index 3d2fe1208900..e5afe9efd3f3 100644 --- a/tools/sched_ext/include/scx/compat.bpf.h +++ b/tools/sched_ext/include/scx/compat.bpf.h @@ -15,6 +15,25 @@ __ret; \ }) +/* v6.12: 819513666966 ("sched_ext: Add cgroup support") */ +#define __COMPAT_scx_bpf_task_cgroup(p) \ + (bpf_ksym_exists(scx_bpf_task_cgroup) ? \ + scx_bpf_task_cgroup((p)) : NULL) + +/* v6.12: 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()") */ +#define __COMPAT_scx_bpf_dispatch_from_dsq_set_slice(it, slice) \ + (bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_slice) ? \ + scx_bpf_dispatch_from_dsq_set_slice((it), (slice)) : (void)0) +#define __COMPAT_scx_bpf_dispatch_from_dsq_set_vtime(it, vtime) \ + (bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_vtime) ? \ + scx_bpf_dispatch_from_dsq_set_vtime((it), (vtime)) : (void)0) +#define __COMPAT_scx_bpf_dispatch_from_dsq(it, p, dsq_id, enq_flags) \ + (bpf_ksym_exists(scx_bpf_dispatch_from_dsq) ? \ + scx_bpf_dispatch_from_dsq((it), (p), (dsq_id), (enq_flags)) : false) +#define __COMPAT_scx_bpf_dispatch_vtime_from_dsq(it, p, dsq_id, enq_flags) \ + (bpf_ksym_exists(scx_bpf_dispatch_vtime_from_dsq) ? \ + scx_bpf_dispatch_vtime_from_dsq((it), (p), (dsq_id), (enq_flags)) : false) + /* * 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/user_exit_info.h b/tools/sched_ext/include/scx/user_exit_info.h index 891693ee604e..8ce2734402e1 100644 --- a/tools/sched_ext/include/scx/user_exit_info.h +++ b/tools/sched_ext/include/scx/user_exit_info.h @@ -25,7 +25,11 @@ struct user_exit_info { #ifdef __bpf__ +#ifdef LSP +#include "../vmlinux/vmlinux.h" +#else #include "vmlinux.h" +#endif #include <bpf/bpf_core_read.h> #define UEI_DEFINE(__name) \ diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c index 3ab2b60781a0..b722baf6da4b 100644 --- a/tools/sched_ext/scx_flatcg.bpf.c +++ b/tools/sched_ext/scx_flatcg.bpf.c @@ -49,7 +49,10 @@ /* * Maximum amount of retries to find a valid cgroup. */ -#define CGROUP_MAX_RETRIES 1024 +enum { + FALLBACK_DSQ = 0, + CGROUP_MAX_RETRIES = 1024, +}; char _license[] SEC("license") = "GPL"; @@ -225,7 +228,7 @@ static void cgrp_refresh_hweight(struct cgroup *cgrp, struct fcg_cgrp_ctx *cgc) break; /* - * We can be oppotunistic here and not grab the + * We can be opportunistic here and not grab the * cgv_tree_lock and deal with the occasional races. * However, hweight updates are already cached and * relatively low-frequency. Let's just do the @@ -258,8 +261,7 @@ static void cgrp_cap_budget(struct cgv_node *cgv_node, struct fcg_cgrp_ctx *cgc) * and thus can't be updated and repositioned. Instead, we collect the * vtime deltas separately and apply it asynchronously here. */ - delta = cgc->cvtime_delta; - __sync_fetch_and_sub(&cgc->cvtime_delta, delta); + delta = __sync_fetch_and_sub(&cgc->cvtime_delta, cgc->cvtime_delta); cvtime = cgv_node->cvtime + delta; /* @@ -378,12 +380,12 @@ void BPF_STRUCT_OPS(fcg_enqueue, struct task_struct *p, u64 enq_flags) scx_bpf_dispatch(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, enq_flags); } else { stat_inc(FCG_STAT_GLOBAL); - scx_bpf_dispatch(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags); + scx_bpf_dispatch(p, FALLBACK_DSQ, SCX_SLICE_DFL, enq_flags); } return; } - cgrp = scx_bpf_task_cgroup(p); + cgrp = __COMPAT_scx_bpf_task_cgroup(p); cgc = find_cgrp_ctx(cgrp); if (!cgc) goto out_release; @@ -509,7 +511,7 @@ void BPF_STRUCT_OPS(fcg_runnable, struct task_struct *p, u64 enq_flags) { struct cgroup *cgrp; - cgrp = scx_bpf_task_cgroup(p); + cgrp = __COMPAT_scx_bpf_task_cgroup(p); update_active_weight_sums(cgrp, true); bpf_cgroup_release(cgrp); } @@ -522,7 +524,7 @@ void BPF_STRUCT_OPS(fcg_running, struct task_struct *p) if (fifo_sched) return; - cgrp = scx_bpf_task_cgroup(p); + cgrp = __COMPAT_scx_bpf_task_cgroup(p); cgc = find_cgrp_ctx(cgrp); if (cgc) { /* @@ -565,7 +567,7 @@ void BPF_STRUCT_OPS(fcg_stopping, struct task_struct *p, bool runnable) if (!taskc->bypassed_at) return; - cgrp = scx_bpf_task_cgroup(p); + cgrp = __COMPAT_scx_bpf_task_cgroup(p); cgc = find_cgrp_ctx(cgrp); if (cgc) { __sync_fetch_and_add(&cgc->cvtime_delta, @@ -579,7 +581,7 @@ void BPF_STRUCT_OPS(fcg_quiescent, struct task_struct *p, u64 deq_flags) { struct cgroup *cgrp; - cgrp = scx_bpf_task_cgroup(p); + cgrp = __COMPAT_scx_bpf_task_cgroup(p); update_active_weight_sums(cgrp, false); bpf_cgroup_release(cgrp); } @@ -781,7 +783,7 @@ void BPF_STRUCT_OPS(fcg_dispatch, s32 cpu, struct task_struct *prev) pick_next_cgroup: cpuc->cur_at = now; - if (scx_bpf_consume(SCX_DSQ_GLOBAL)) { + if (scx_bpf_consume(FALLBACK_DSQ)) { cpuc->cur_cgid = 0; return; } @@ -838,7 +840,7 @@ int BPF_STRUCT_OPS_SLEEPABLE(fcg_cgroup_init, struct cgroup *cgrp, int ret; /* - * Technically incorrect as cgroup ID is full 64bit while dq ID is + * Technically incorrect as cgroup ID is full 64bit while dsq ID is * 63bit. Should not be a problem in practice and easy to spot in the * unlikely case that it breaks. */ @@ -926,6 +928,11 @@ void BPF_STRUCT_OPS(fcg_cgroup_move, struct task_struct *p, p->scx.dsq_vtime = to_cgc->tvtime_now + vtime_delta; } +s32 BPF_STRUCT_OPS_SLEEPABLE(fcg_init) +{ + return scx_bpf_create_dsq(FALLBACK_DSQ, -1); +} + void BPF_STRUCT_OPS(fcg_exit, struct scx_exit_info *ei) { UEI_RECORD(uei, ei); @@ -944,6 +951,7 @@ SCX_OPS_DEFINE(flatcg_ops, .cgroup_init = (void *)fcg_cgroup_init, .cgroup_exit = (void *)fcg_cgroup_exit, .cgroup_move = (void *)fcg_cgroup_move, + .init = (void *)fcg_init, .exit = (void *)fcg_exit, .flags = SCX_OPS_HAS_CGROUP_WEIGHT | SCX_OPS_ENQ_EXITING, .name = "flatcg"); diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c index 83c8f54c1e31..67e2a7968cc9 100644 --- a/tools/sched_ext/scx_qmap.bpf.c +++ b/tools/sched_ext/scx_qmap.bpf.c @@ -318,11 +318,11 @@ static bool dispatch_highpri(bool from_timer) if (tctx->highpri) { /* exercise the set_*() and vtime interface too */ - scx_bpf_dispatch_from_dsq_set_slice( + __COMPAT_scx_bpf_dispatch_from_dsq_set_slice( BPF_FOR_EACH_ITER, slice_ns * 2); - scx_bpf_dispatch_from_dsq_set_vtime( + __COMPAT_scx_bpf_dispatch_from_dsq_set_vtime( BPF_FOR_EACH_ITER, highpri_seq++); - scx_bpf_dispatch_vtime_from_dsq( + __COMPAT_scx_bpf_dispatch_vtime_from_dsq( BPF_FOR_EACH_ITER, p, HIGHPRI_DSQ, 0); } } @@ -340,9 +340,9 @@ static bool dispatch_highpri(bool from_timer) else cpu = scx_bpf_pick_any_cpu(p->cpus_ptr, 0); - if (scx_bpf_dispatch_from_dsq(BPF_FOR_EACH_ITER, p, - SCX_DSQ_LOCAL_ON | cpu, - SCX_ENQ_PREEMPT)) { + if (__COMPAT_scx_bpf_dispatch_from_dsq(BPF_FOR_EACH_ITER, p, + SCX_DSQ_LOCAL_ON | cpu, + SCX_ENQ_PREEMPT)) { if (cpu == this_cpu) { dispatched = true; __sync_fetch_and_add(&nr_expedited_local, 1); |