#define CREATE_TRACE_POINTS
#include <trace/events/sched_ext.h>
+static void process_ddsp_deferred_locals(struct rq *rq);
static void scx_bpf_kick_cpu(s32 cpu, u64 flags);
static __printf(3, 4) void scx_ops_exit_kind(enum scx_exit_kind kind,
s64 exit_code,
return -EPROTO;
}
+static void run_deferred(struct rq *rq)
+{
+ process_ddsp_deferred_locals(rq);
+}
+
+#ifdef CONFIG_SMP
+static void deferred_bal_cb_workfn(struct rq *rq)
+{
+ run_deferred(rq);
+}
+#endif
+
+static void deferred_irq_workfn(struct irq_work *irq_work)
+{
+ struct rq *rq = container_of(irq_work, struct rq, scx.deferred_irq_work);
+
+ raw_spin_rq_lock(rq);
+ run_deferred(rq);
+ raw_spin_rq_unlock(rq);
+}
+
+/**
+ * schedule_deferred - Schedule execution of deferred actions on an rq
+ * @rq: target rq
+ *
+ * Schedule execution of deferred actions on @rq. Must be called with @rq
+ * locked. Deferred actions are executed with @rq locked but unpinned, and thus
+ * can unlock @rq to e.g. migrate tasks to other rqs.
+ */
+static void schedule_deferred(struct rq *rq)
+{
+ lockdep_assert_rq_held(rq);
+
+#ifdef CONFIG_SMP
+ /*
+ * If in the middle of waking up a task, task_woken_scx() will be called
+ * afterwards which will then run the deferred actions, no need to
+ * schedule anything.
+ */
+ if (rq->scx.flags & SCX_RQ_IN_WAKEUP)
+ return;
+
+ /*
+ * If in balance, the balance callbacks will be called before rq lock is
+ * released. Schedule one.
+ */
+ if (rq->scx.flags & SCX_RQ_IN_BALANCE) {
+ queue_balance_callback(rq, &rq->scx.deferred_bal_cb,
+ deferred_bal_cb_workfn);
+ return;
+ }
+#endif
+ /*
+ * No scheduler hooks available. Queue an irq work. They are executed on
+ * IRQ re-enable which may take a bit longer than the scheduler hooks.
+ * The above WAKEUP and BALANCE paths should cover most of the cases and
+ * the time to IRQ re-enable shouldn't be long.
+ */
+ irq_work_queue(&rq->scx.deferred_irq_work);
+}
+
/**
* touch_core_sched - Update timestamp used for core-sched task ordering
* @rq: rq to read clock from, must be locked
bool is_local = dsq == &rq->scx.local_dsq;
if (!dsq) {
- WARN_ON_ONCE(!list_empty(&p->scx.dsq_list.node));
+ /*
+ * If !dsq && on-list, @p is on @rq's ddsp_deferred_locals.
+ * Unlinking is all that's needed to cancel.
+ */
+ if (unlikely(!list_empty(&p->scx.dsq_list.node)))
+ list_del_init(&p->scx.dsq_list.node);
+
/*
* When dispatching directly from the BPF scheduler to a local
* DSQ, the task isn't associated with any DSQ but
*/
if (p->scx.holding_cpu >= 0)
p->scx.holding_cpu = -1;
+
return;
}
return;
}
- /*
- * %SCX_DSQ_LOCAL_ON is not supported during direct dispatch because
- * dispatching to the local DSQ of a different CPU requires unlocking
- * the current rq which isn't allowed in the enqueue path. Use
- * ops.select_cpu() to be on the target CPU and then %SCX_DSQ_LOCAL.
- */
- if (unlikely((dsq_id & SCX_DSQ_LOCAL_ON) == SCX_DSQ_LOCAL_ON)) {
- scx_ops_error("SCX_DSQ_LOCAL_ON can't be used for direct-dispatch");
- return;
- }
-
WARN_ON_ONCE(p->scx.ddsp_dsq_id != SCX_DSQ_INVALID);
WARN_ON_ONCE(p->scx.ddsp_enq_flags);
static void direct_dispatch(struct task_struct *p, u64 enq_flags)
{
+ struct rq *rq = task_rq(p);
struct scx_dispatch_q *dsq;
+ u64 dsq_id = p->scx.ddsp_dsq_id;
+
+ touch_core_sched_dispatch(rq, p);
+
+ p->scx.ddsp_enq_flags |= enq_flags;
+
+ /*
+ * We are in the enqueue path with @rq locked and pinned, and thus can't
+ * double lock a remote rq and enqueue to its local DSQ. For
+ * DSQ_LOCAL_ON verdicts targeting the local DSQ of a remote CPU, defer
+ * the enqueue so that it's executed when @rq can be unlocked.
+ */
+ if ((dsq_id & SCX_DSQ_LOCAL_ON) == SCX_DSQ_LOCAL_ON) {
+ s32 cpu = dsq_id & SCX_DSQ_LOCAL_CPU_MASK;
+ unsigned long opss;
- touch_core_sched_dispatch(task_rq(p), p);
+ if (cpu == cpu_of(rq)) {
+ dsq_id = SCX_DSQ_LOCAL;
+ goto dispatch;
+ }
+
+ opss = atomic_long_read(&p->scx.ops_state) & SCX_OPSS_STATE_MASK;
+
+ switch (opss & SCX_OPSS_STATE_MASK) {
+ case SCX_OPSS_NONE:
+ break;
+ case SCX_OPSS_QUEUEING:
+ /*
+ * As @p was never passed to the BPF side, _release is
+ * not strictly necessary. Still do it for consistency.
+ */
+ atomic_long_set_release(&p->scx.ops_state, SCX_OPSS_NONE);
+ break;
+ default:
+ WARN_ONCE(true, "sched_ext: %s[%d] has invalid ops state 0x%lx in direct_dispatch()",
+ p->comm, p->pid, opss);
+ atomic_long_set_release(&p->scx.ops_state, SCX_OPSS_NONE);
+ break;
+ }
- enq_flags |= (p->scx.ddsp_enq_flags | SCX_ENQ_CLEAR_OPSS);
- dsq = find_dsq_for_dispatch(task_rq(p), p->scx.ddsp_dsq_id, p);
- dispatch_enqueue(dsq, p, enq_flags);
+ WARN_ON_ONCE(p->scx.dsq || !list_empty(&p->scx.dsq_list.node));
+ list_add_tail(&p->scx.dsq_list.node,
+ &rq->scx.ddsp_deferred_locals);
+ schedule_deferred(rq);
+ return;
+ }
+
+dispatch:
+ dsq = find_dsq_for_dispatch(rq, dsq_id, p);
+ dispatch_enqueue(dsq, p, p->scx.ddsp_enq_flags | SCX_ENQ_CLEAR_OPSS);
}
static bool scx_rq_online(struct rq *rq)
}
}
+static void process_ddsp_deferred_locals(struct rq *rq)
+{
+ struct task_struct *p, *tmp;
+
+ lockdep_assert_rq_held(rq);
+
+ /*
+ * Now that @rq can be unlocked, execute the deferred enqueueing of
+ * tasks directly dispatched to the local DSQs of other CPUs. See
+ * direct_dispatch().
+ */
+ list_for_each_entry_safe(p, tmp, &rq->scx.ddsp_deferred_locals,
+ scx.dsq_list.node) {
+ s32 ret;
+
+ list_del_init(&p->scx.dsq_list.node);
+
+ ret = dispatch_to_local_dsq(rq, p->scx.ddsp_dsq_id, p,
+ p->scx.ddsp_enq_flags);
+ WARN_ON_ONCE(ret == DTL_NOT_LOCAL);
+ }
+}
+
static void put_prev_task_scx(struct rq *rq, struct task_struct *p)
{
#ifndef CONFIG_SMP
}
}
+static void task_woken_scx(struct rq *rq, struct task_struct *p)
+{
+ run_deferred(rq);
+}
+
static void set_cpus_allowed_scx(struct task_struct *p,
struct affinity_context *ac)
{
*
* - task_fork/dead: We need fork/dead notifications for all tasks regardless of
* their current sched_class. Call them directly from sched core instead.
- *
- * - task_woken: Unnecessary.
*/
DEFINE_SCHED_CLASS(ext) = {
.enqueue_task = enqueue_task_scx,
#ifdef CONFIG_SMP
.balance = balance_scx,
.select_task_rq = select_task_rq_scx,
+ .task_woken = task_woken_scx,
.set_cpus_allowed = set_cpus_allowed_scx,
.rq_online = rq_online_scx,
init_dsq(&rq->scx.local_dsq, SCX_DSQ_LOCAL);
INIT_LIST_HEAD(&rq->scx.runnable_list);
+ INIT_LIST_HEAD(&rq->scx.ddsp_deferred_locals);
BUG_ON(!zalloc_cpumask_var(&rq->scx.cpus_to_kick, GFP_KERNEL));
BUG_ON(!zalloc_cpumask_var(&rq->scx.cpus_to_kick_if_idle, GFP_KERNEL));
BUG_ON(!zalloc_cpumask_var(&rq->scx.cpus_to_preempt, GFP_KERNEL));
BUG_ON(!zalloc_cpumask_var(&rq->scx.cpus_to_wait, GFP_KERNEL));
+ init_irq_work(&rq->scx.deferred_irq_work, deferred_irq_workfn);
init_irq_work(&rq->scx.kick_cpus_irq_work, kick_cpus_irq_workfn);
if (cpu_online(cpu))
projects / thirdparty / linux.git / commitdiff
