summaryrefslogtreecommitdiff
path: root/kernel/sched/cpudeadline.c
blob: 95baa12a10293e0e92b7a65dbb63add7c23caa12 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
// SPDX-License-Identifier: GPL-2.0-only
/*
 *  kernel/sched/cpudeadline.c
 *
 *  Global CPU deadline management
 *
 *  Author: Juri Lelli <j.lelli@sssup.it>
 */

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 void cpudl_heapify_down(struct cpudl *cp, int idx)
{
	int l, r, largest;

	int orig_cpu = cp->elements[idx].cpu;
	u64 orig_dl = cp->elements[idx].dl;

	if (left_child(idx) >= cp->size)
		return;

	/* adapted from lib/prio_heap.c */
	while (1) {
		u64 largest_dl;

		l = left_child(idx);
		r = right_child(idx);
		largest = idx;
		largest_dl = orig_dl;

		if ((l < cp->size) && dl_time_before(orig_dl,
						cp->elements[l].dl)) {
			largest = l;
			largest_dl = cp->elements[l].dl;
		}
		if ((r < cp->size) && dl_time_before(largest_dl,
						cp->elements[r].dl))
			largest = r;

		if (largest == idx)
			break;

		/* pull largest child onto idx */
		cp->elements[idx].cpu = cp->elements[largest].cpu;
		cp->elements[idx].dl = cp->elements[largest].dl;
		cp->elements[cp->elements[idx].cpu].idx = idx;
		idx = largest;
	}
	/* actual push down of saved original values orig_* */
	cp->elements[idx].cpu = orig_cpu;
	cp->elements[idx].dl = orig_dl;
	cp->elements[cp->elements[idx].cpu].idx = idx;
}

static void cpudl_heapify_up(struct cpudl *cp, int idx)
{
	int p;

	int orig_cpu = cp->elements[idx].cpu;
	u64 orig_dl = cp->elements[idx].dl;

	if (idx == 0)
		return;

	do {
		p = parent(idx);
		if (dl_time_before(orig_dl, cp->elements[p].dl))
			break;
		/* pull parent onto idx */
		cp->elements[idx].cpu = cp->elements[p].cpu;
		cp->elements[idx].dl = cp->elements[p].dl;
		cp->elements[cp->elements[idx].cpu].idx = idx;
		idx = p;
	} while (idx != 0);
	/* actual push up of saved original values orig_* */
	cp->elements[idx].cpu = orig_cpu;
	cp->elements[idx].dl = orig_dl;
	cp->elements[cp->elements[idx].cpu].idx = idx;
}

static void cpudl_heapify(struct cpudl *cp, int idx)
{
	if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
				cp->elements[idx].dl))
		cpudl_heapify_up(cp, idx);
	else
		cpudl_heapify_down(cp, 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 - CPUs were found
 */
int cpudl_find(struct cpudl *cp, struct task_struct *p,
	       struct cpumask *later_mask)
{
	const struct sched_dl_entity *dl_se = &p->dl;

	if (later_mask &&
	    cpumask_and(later_mask, cp->free_cpus, &p->cpus_mask)) {
		unsigned long cap, max_cap = 0;
		int cpu, max_cpu = -1;

		if (!sched_asym_cpucap_active())
			return 1;

		/* Ensure the capacity of the CPUs fits the task. */
		for_each_cpu(cpu, later_mask) {
			if (!dl_task_fits_capacity(p, cpu)) {
				cpumask_clear_cpu(cpu, later_mask);

				cap = arch_scale_cpu_capacity(cpu);

				if (cap > max_cap ||
				    (cpu == task_cpu(p) && cap == max_cap)) {
					max_cap = cap;
					max_cpu = cpu;
				}
			}
		}

		if (cpumask_empty(later_mask))
			cpumask_set_cpu(max_cpu, later_mask);

		return 1;
	} else {
		int best_cpu = cpudl_maximum(cp);

		WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));

		if (cpumask_test_cpu(best_cpu, &p->cpus_mask) &&
		    dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
			if (later_mask)
				cpumask_set_cpu(best_cpu, later_mask);

			return 1;
		}
	}
	return 0;
}

/*
 * cpudl_clear - remove a CPU from the cpudl max-heap
 * @cp: the cpudl max-heap context
 * @cpu: the target CPU
 *
 * Notes: assumes cpu_rq(cpu)->lock is locked
 *
 * Returns: (void)
 */
void cpudl_clear(struct cpudl *cp, int cpu)
{
	int old_idx, new_cpu;
	unsigned long flags;

	WARN_ON(!cpu_present(cpu));

	raw_spin_lock_irqsave(&cp->lock, flags);

	old_idx = cp->elements[cpu].idx;
	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.
		 */
	} else {
		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->elements[new_cpu].idx = old_idx;
		cp->elements[cpu].idx = IDX_INVALID;
		cpudl_heapify(cp, old_idx);

		cpumask_set_cpu(cpu, cp->free_cpus);
	}
	raw_spin_unlock_irqrestore(&cp->lock, flags);
}

/*
 * 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 old_idx;
	unsigned long flags;

	WARN_ON(!cpu_present(cpu));

	raw_spin_lock_irqsave(&cp->lock, flags);

	old_idx = cp->elements[cpu].idx;
	if (old_idx == IDX_INVALID) {
		int new_idx = cp->size++;

		cp->elements[new_idx].dl = dl;
		cp->elements[new_idx].cpu = cpu;
		cp->elements[cpu].idx = new_idx;
		cpudl_heapify_up(cp, new_idx);
		cpumask_clear_cpu(cpu, cp->free_cpus);
	} else {
		cp->elements[old_idx].dl = dl;
		cpudl_heapify(cp, old_idx);
	}

	raw_spin_unlock_irqrestore(&cp->lock, flags);
}

/*
 * cpudl_set_freecpu - Set the cpudl.free_cpus
 * @cp: the cpudl max-heap context
 * @cpu: rd attached CPU
 */
void cpudl_set_freecpu(struct cpudl *cp, int cpu)
{
	cpumask_set_cpu(cpu, cp->free_cpus);
}

/*
 * cpudl_clear_freecpu - Clear the cpudl.free_cpus
 * @cp: the cpudl max-heap context
 * @cpu: rd attached CPU
 */
void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
{
	cpumask_clear_cpu(cpu, cp->free_cpus);
}

/*
 * cpudl_init - initialize the cpudl structure
 * @cp: the cpudl max-heap context
 */
int cpudl_init(struct cpudl *cp)
{
	int i;

	raw_spin_lock_init(&cp->lock);
	cp->size = 0;

	cp->elements = kcalloc(nr_cpu_ids,
			       sizeof(struct cpudl_item),
			       GFP_KERNEL);
	if (!cp->elements)
		return -ENOMEM;

	if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
		kfree(cp->elements);
		return -ENOMEM;
	}

	for_each_possible_cpu(i)
		cp->elements[i].idx = IDX_INVALID;

	return 0;
}

/*
 * cpudl_cleanup - clean up the cpudl structure
 * @cp: the cpudl max-heap context
 */
void cpudl_cleanup(struct cpudl *cp)
{
	free_cpumask_var(cp->free_cpus);
	kfree(cp->elements);
}