![Juri Lelli](/assets/img/avatar_default.png)
Commit 82b9580
("sched/deadline: Test for CPU's presence explicitly")
changed how we check if a CPU returned by cpudeadline machinery is
valid. But, we don't want to call cpu_present() if best_cpu is
equal to -1. So, switch the order of tests inside WARN_ON().
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: boris.ostrovsky@oracle.com
Cc: konrad.wilk@oracle.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1393238832-9100-1-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
217 lines
4.9 KiB
C
217 lines
4.9 KiB
C
/*
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* kernel/sched/cpudl.c
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*
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* Global CPU deadline management
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*
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* Author: Juri Lelli <j.lelli@sssup.it>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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*/
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#include <linux/gfp.h>
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#include <linux/kernel.h>
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#include "cpudeadline.h"
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static inline int parent(int i)
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{
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return (i - 1) >> 1;
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}
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static inline int left_child(int i)
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{
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return (i << 1) + 1;
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}
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static inline int right_child(int i)
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{
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return (i << 1) + 2;
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}
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static inline int dl_time_before(u64 a, u64 b)
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{
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return (s64)(a - b) < 0;
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}
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static void cpudl_exchange(struct cpudl *cp, int a, int b)
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{
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int cpu_a = cp->elements[a].cpu, cpu_b = cp->elements[b].cpu;
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swap(cp->elements[a], cp->elements[b]);
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swap(cp->cpu_to_idx[cpu_a], cp->cpu_to_idx[cpu_b]);
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}
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static void cpudl_heapify(struct cpudl *cp, int idx)
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{
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int l, r, largest;
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/* adapted from lib/prio_heap.c */
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while(1) {
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l = left_child(idx);
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r = right_child(idx);
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largest = idx;
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if ((l < cp->size) && dl_time_before(cp->elements[idx].dl,
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cp->elements[l].dl))
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largest = l;
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if ((r < cp->size) && dl_time_before(cp->elements[largest].dl,
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cp->elements[r].dl))
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largest = r;
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if (largest == idx)
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break;
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/* Push idx down the heap one level and bump one up */
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cpudl_exchange(cp, largest, idx);
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idx = largest;
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}
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}
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static void cpudl_change_key(struct cpudl *cp, int idx, u64 new_dl)
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{
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WARN_ON(idx == IDX_INVALID || !cpu_present(idx));
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if (dl_time_before(new_dl, cp->elements[idx].dl)) {
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cp->elements[idx].dl = new_dl;
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cpudl_heapify(cp, idx);
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} else {
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cp->elements[idx].dl = new_dl;
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while (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
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cp->elements[idx].dl)) {
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cpudl_exchange(cp, idx, parent(idx));
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idx = parent(idx);
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}
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}
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}
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static inline int cpudl_maximum(struct cpudl *cp)
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{
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return cp->elements[0].cpu;
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}
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/*
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* cpudl_find - find the best (later-dl) CPU in the system
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* @cp: the cpudl max-heap context
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* @p: the task
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* @later_mask: a mask to fill in with the selected CPUs (or NULL)
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*
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* Returns: int - best CPU (heap maximum if suitable)
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*/
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int cpudl_find(struct cpudl *cp, struct task_struct *p,
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struct cpumask *later_mask)
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{
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int best_cpu = -1;
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const struct sched_dl_entity *dl_se = &p->dl;
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if (later_mask && cpumask_and(later_mask, cp->free_cpus,
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&p->cpus_allowed) && cpumask_and(later_mask,
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later_mask, cpu_active_mask)) {
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best_cpu = cpumask_any(later_mask);
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goto out;
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} else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) &&
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dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
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best_cpu = cpudl_maximum(cp);
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if (later_mask)
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cpumask_set_cpu(best_cpu, later_mask);
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}
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out:
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WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
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return best_cpu;
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}
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/*
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* cpudl_set - update the cpudl max-heap
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* @cp: the cpudl max-heap context
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* @cpu: the target cpu
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* @dl: the new earliest deadline for this cpu
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*
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* Notes: assumes cpu_rq(cpu)->lock is locked
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*
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* Returns: (void)
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*/
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void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
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{
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int old_idx, new_cpu;
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unsigned long flags;
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WARN_ON(!cpu_present(cpu));
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raw_spin_lock_irqsave(&cp->lock, flags);
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old_idx = cp->cpu_to_idx[cpu];
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if (!is_valid) {
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/* remove item */
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if (old_idx == IDX_INVALID) {
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/*
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* Nothing to remove if old_idx was invalid.
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* This could happen if a rq_offline_dl is
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* called for a CPU without -dl tasks running.
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*/
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goto out;
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}
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new_cpu = cp->elements[cp->size - 1].cpu;
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cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
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cp->elements[old_idx].cpu = new_cpu;
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cp->size--;
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cp->cpu_to_idx[new_cpu] = old_idx;
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cp->cpu_to_idx[cpu] = IDX_INVALID;
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while (old_idx > 0 && dl_time_before(
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cp->elements[parent(old_idx)].dl,
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cp->elements[old_idx].dl)) {
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cpudl_exchange(cp, old_idx, parent(old_idx));
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old_idx = parent(old_idx);
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}
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cpumask_set_cpu(cpu, cp->free_cpus);
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cpudl_heapify(cp, old_idx);
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goto out;
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}
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if (old_idx == IDX_INVALID) {
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cp->size++;
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cp->elements[cp->size - 1].dl = 0;
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cp->elements[cp->size - 1].cpu = cpu;
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cp->cpu_to_idx[cpu] = cp->size - 1;
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cpudl_change_key(cp, cp->size - 1, dl);
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cpumask_clear_cpu(cpu, cp->free_cpus);
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} else {
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cpudl_change_key(cp, old_idx, dl);
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}
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out:
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raw_spin_unlock_irqrestore(&cp->lock, flags);
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}
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/*
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* cpudl_init - initialize the cpudl structure
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* @cp: the cpudl max-heap context
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*/
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int cpudl_init(struct cpudl *cp)
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{
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int i;
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memset(cp, 0, sizeof(*cp));
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raw_spin_lock_init(&cp->lock);
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cp->size = 0;
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for (i = 0; i < NR_CPUS; i++)
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cp->cpu_to_idx[i] = IDX_INVALID;
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if (!alloc_cpumask_var(&cp->free_cpus, GFP_KERNEL))
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return -ENOMEM;
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cpumask_setall(cp->free_cpus);
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return 0;
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}
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/*
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* cpudl_cleanup - clean up the cpudl structure
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* @cp: the cpudl max-heap context
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*/
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void cpudl_cleanup(struct cpudl *cp)
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{
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/*
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* nothing to do for the moment
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*/
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}
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