1 files changed, 216 insertions, 0 deletions

diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
new file mode 100644
index 000000000000..045fc74e3f09
--- /dev/null
+++ b/kernel/sched/cpudeadline.c
@@ -0,0 +1,216 @@
+/*
+ *  kernel/sched/cpudl.c
+ *
+ *  Global CPU deadline management
+ *
+ *  Author: Juri Lelli <j.lelli@sssup.it>
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License
+ *  as published by the Free Software Foundation; version 2
+ *  of the License.
+ */
+
+#include <linux/gfp.h>
+#include <linux/kernel.h>
+#include "cpudeadline.h"
+
+static inline int parent(int i)
+{
+        return (i - 1) >> 1;
+}
+
+static inline int left_child(int i)
+{
+        return (i << 1) + 1;
+}
+
+static inline int right_child(int i)
+{
+        return (i << 1) + 2;
+}
+
+static inline int dl_time_before(u64 a, u64 b)
+{
+        return (s64)(a - b) < 0;
+}
+
+static void cpudl_exchange(struct cpudl *cp, int a, int b)
+{
+        int cpu_a = cp->elements[a].cpu, cpu_b = cp->elements[b].cpu;
+
+        swap(cp->elements[a], cp->elements[b]);
+        swap(cp->cpu_to_idx[cpu_a], cp->cpu_to_idx[cpu_b]);
+}
+
+static void cpudl_heapify(struct cpudl *cp, int idx)
+{
+        int l, r, largest;
+
+        /* adapted from lib/prio_heap.c */
+        while(1) {
+                l = left_child(idx);
+                r = right_child(idx);
+                largest = idx;
+
+                if ((l < cp->size) && dl_time_before(cp->elements[idx].dl,
+                                                        cp->elements[l].dl))
+                        largest = l;
+                if ((r < cp->size) && dl_time_before(cp->elements[largest].dl,
+                                                        cp->elements[r].dl))
+                        largest = r;
+                if (largest == idx)
+                        break;
+
+                /* Push idx down the heap one level and bump one up */
+                cpudl_exchange(cp, largest, idx);
+                idx = largest;
+        }
+}
+
+static void cpudl_change_key(struct cpudl *cp, int idx, u64 new_dl)
+{
+        WARN_ON(idx > num_present_cpus() || idx == IDX_INVALID);
+
+        if (dl_time_before(new_dl, cp->elements[idx].dl)) {
+                cp->elements[idx].dl = new_dl;
+                cpudl_heapify(cp, idx);
+        } else {
+                cp->elements[idx].dl = new_dl;
+                while (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
+                                        cp->elements[idx].dl)) {
+                        cpudl_exchange(cp, idx, parent(idx));
+                        idx = parent(idx);
+                }
+        }
+}
+
+static inline int cpudl_maximum(struct cpudl *cp)
+{
+        return cp->elements[0].cpu;
+}
+
+/*
+ * cpudl_find - find the best (later-dl) CPU in the system
+ * @cp: the cpudl max-heap context
+ * @p: the task
+ * @later_mask: a mask to fill in with the selected CPUs (or NULL)
+ *
+ * Returns: int - best CPU (heap maximum if suitable)
+ */
+int cpudl_find(struct cpudl *cp, struct task_struct *p,
+               struct cpumask *later_mask)
+{
+        int best_cpu = -1;
+        const struct sched_dl_entity *dl_se = &p->dl;
+
+        if (later_mask && cpumask_and(later_mask, cp->free_cpus,
+                        &p->cpus_allowed) && cpumask_and(later_mask,
+                        later_mask, cpu_active_mask)) {
+                best_cpu = cpumask_any(later_mask);
+                goto out;
+        } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) &&
+                        dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
+                best_cpu = cpudl_maximum(cp);
+                if (later_mask)
+                        cpumask_set_cpu(best_cpu, later_mask);
+        }
+
+out:
+        WARN_ON(best_cpu > num_present_cpus() && best_cpu != -1);
+
+        return best_cpu;
+}
+
+/*
+ * cpudl_set - update the cpudl max-heap
+ * @cp: the cpudl max-heap context
+ * @cpu: the target cpu
+ * @dl: the new earliest deadline for this cpu
+ *
+ * Notes: assumes cpu_rq(cpu)->lock is locked
+ *
+ * Returns: (void)
+ */
+void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
+{
+        int old_idx, new_cpu;
+        unsigned long flags;
+
+        WARN_ON(cpu > num_present_cpus());
+
+        raw_spin_lock_irqsave(&cp->lock, flags);
+        old_idx = cp->cpu_to_idx[cpu];
+        if (!is_valid) {
+                /* remove item */
+                if (old_idx == IDX_INVALID) {
+                        /*
+                         * Nothing to remove if old_idx was invalid.
+                         * This could happen if a rq_offline_dl is
+                         * called for a CPU without -dl tasks running.
+                         */
+                        goto out;
+                }
+                new_cpu = cp->elements[cp->size - 1].cpu;
+                cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
+                cp->elements[old_idx].cpu = new_cpu;
+                cp->size--;
+                cp->cpu_to_idx[new_cpu] = old_idx;
+                cp->cpu_to_idx[cpu] = IDX_INVALID;
+                while (old_idx > 0 && dl_time_before(
+                                cp->elements[parent(old_idx)].dl,
+                                cp->elements[old_idx].dl)) {
+                        cpudl_exchange(cp, old_idx, parent(old_idx));
+                        old_idx = parent(old_idx);
+                }
+                cpumask_set_cpu(cpu, cp->free_cpus);
+                cpudl_heapify(cp, old_idx);
+
+                goto out;
+        }
+
+        if (old_idx == IDX_INVALID) {
+                cp->size++;
+                cp->elements[cp->size - 1].dl = 0;
+                cp->elements[cp->size - 1].cpu = cpu;
+                cp->cpu_to_idx[cpu] = cp->size - 1;
+                cpudl_change_key(cp, cp->size - 1, dl);
+                cpumask_clear_cpu(cpu, cp->free_cpus);
+        } else {
+                cpudl_change_key(cp, old_idx, dl);
+        }
+
+out:
+        raw_spin_unlock_irqrestore(&cp->lock, flags);
+}
+
+/*
+ * cpudl_init - initialize the cpudl structure
+ * @cp: the cpudl max-heap context
+ */
+int cpudl_init(struct cpudl *cp)
+{
+        int i;
+
+        memset(cp, 0, sizeof(*cp));
+        raw_spin_lock_init(&cp->lock);
+        cp->size = 0;
+        for (i = 0; i < NR_CPUS; i++)
+                cp->cpu_to_idx[i] = IDX_INVALID;
+        if (!alloc_cpumask_var(&cp->free_cpus, GFP_KERNEL))
+                return -ENOMEM;
+        cpumask_setall(cp->free_cpus);
+
+        return 0;
+}
+
+/*
+ * cpudl_cleanup - clean up the cpudl structure
+ * @cp: the cpudl max-heap context
+ */
+void cpudl_cleanup(struct cpudl *cp)
+{
+        /*
+         * nothing to do for the moment
+         */
+}