summaryrefslogtreecommitdiff
path: root/kernel/sched/isolation.c
blob: 5891e715f00d028b0d2f4fd157e99f319b899a1d (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Housekeeping management. Manage the targets for routine code that can run on
 *  any CPU: unbound workqueues, timers, kthreads and any offloadable work.
 *
 * Copyright (C) 2017 Red Hat, Inc., Frederic Weisbecker
 * Copyright (C) 2017-2018 SUSE, Frederic Weisbecker
 *
 */

enum hk_flags {
	HK_FLAG_TIMER		= BIT(HK_TYPE_TIMER),
	HK_FLAG_RCU		= BIT(HK_TYPE_RCU),
	HK_FLAG_MISC		= BIT(HK_TYPE_MISC),
	HK_FLAG_SCHED		= BIT(HK_TYPE_SCHED),
	HK_FLAG_TICK		= BIT(HK_TYPE_TICK),
	HK_FLAG_DOMAIN		= BIT(HK_TYPE_DOMAIN),
	HK_FLAG_WQ		= BIT(HK_TYPE_WQ),
	HK_FLAG_MANAGED_IRQ	= BIT(HK_TYPE_MANAGED_IRQ),
	HK_FLAG_KTHREAD		= BIT(HK_TYPE_KTHREAD),
};

DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
EXPORT_SYMBOL_GPL(housekeeping_overridden);

struct housekeeping {
	cpumask_var_t cpumasks[HK_TYPE_MAX];
	unsigned long flags;
};

static struct housekeeping housekeeping;

bool housekeeping_enabled(enum hk_type type)
{
	return !!(housekeeping.flags & BIT(type));
}
EXPORT_SYMBOL_GPL(housekeeping_enabled);

int housekeeping_any_cpu(enum hk_type type)
{
	int cpu;

	if (static_branch_unlikely(&housekeeping_overridden)) {
		if (housekeeping.flags & BIT(type)) {
			cpu = sched_numa_find_closest(housekeeping.cpumasks[type], smp_processor_id());
			if (cpu < nr_cpu_ids)
				return cpu;

			cpu = cpumask_any_and(housekeeping.cpumasks[type], cpu_online_mask);
			if (likely(cpu < nr_cpu_ids))
				return cpu;
			/*
			 * Unless we have another problem this can only happen
			 * at boot time before start_secondary() brings the 1st
			 * housekeeping CPU up.
			 */
			WARN_ON_ONCE(system_state == SYSTEM_RUNNING ||
				     type != HK_TYPE_TIMER);
		}
	}
	return smp_processor_id();
}
EXPORT_SYMBOL_GPL(housekeeping_any_cpu);

const struct cpumask *housekeeping_cpumask(enum hk_type type)
{
	if (static_branch_unlikely(&housekeeping_overridden))
		if (housekeeping.flags & BIT(type))
			return housekeeping.cpumasks[type];
	return cpu_possible_mask;
}
EXPORT_SYMBOL_GPL(housekeeping_cpumask);

void housekeeping_affine(struct task_struct *t, enum hk_type type)
{
	if (static_branch_unlikely(&housekeeping_overridden))
		if (housekeeping.flags & BIT(type))
			set_cpus_allowed_ptr(t, housekeeping.cpumasks[type]);
}
EXPORT_SYMBOL_GPL(housekeeping_affine);

bool housekeeping_test_cpu(int cpu, enum hk_type type)
{
	if (static_branch_unlikely(&housekeeping_overridden))
		if (housekeeping.flags & BIT(type))
			return cpumask_test_cpu(cpu, housekeeping.cpumasks[type]);
	return true;
}
EXPORT_SYMBOL_GPL(housekeeping_test_cpu);

void __init housekeeping_init(void)
{
	enum hk_type type;

	if (!housekeeping.flags)
		return;

	static_branch_enable(&housekeeping_overridden);

	if (housekeeping.flags & HK_FLAG_TICK)
		sched_tick_offload_init();

	for_each_set_bit(type, &housekeeping.flags, HK_TYPE_MAX) {
		/* We need at least one CPU to handle housekeeping work */
		WARN_ON_ONCE(cpumask_empty(housekeeping.cpumasks[type]));
	}
}

static void __init housekeeping_setup_type(enum hk_type type,
					   cpumask_var_t housekeeping_staging)
{

	alloc_bootmem_cpumask_var(&housekeeping.cpumasks[type]);
	cpumask_copy(housekeeping.cpumasks[type],
		     housekeeping_staging);
}

static int __init housekeeping_setup(char *str, unsigned long flags)
{
	cpumask_var_t non_housekeeping_mask, housekeeping_staging;
	unsigned int first_cpu;
	int err = 0;

	if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK)) {
		if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) {
			pr_warn("Housekeeping: nohz unsupported."
				" Build with CONFIG_NO_HZ_FULL\n");
			return 0;
		}
	}

	alloc_bootmem_cpumask_var(&non_housekeeping_mask);
	if (cpulist_parse(str, non_housekeeping_mask) < 0) {
		pr_warn("Housekeeping: nohz_full= or isolcpus= incorrect CPU range\n");
		goto free_non_housekeeping_mask;
	}

	alloc_bootmem_cpumask_var(&housekeeping_staging);
	cpumask_andnot(housekeeping_staging,
		       cpu_possible_mask, non_housekeeping_mask);

	first_cpu = cpumask_first_and(cpu_present_mask, housekeeping_staging);
	if (first_cpu >= nr_cpu_ids || first_cpu >= setup_max_cpus) {
		__cpumask_set_cpu(smp_processor_id(), housekeeping_staging);
		__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
		if (!housekeeping.flags) {
			pr_warn("Housekeeping: must include one present CPU, "
				"using boot CPU:%d\n", smp_processor_id());
		}
	}

	if (cpumask_empty(non_housekeeping_mask))
		goto free_housekeeping_staging;

	if (!housekeeping.flags) {
		/* First setup call ("nohz_full=" or "isolcpus=") */
		enum hk_type type;

		for_each_set_bit(type, &flags, HK_TYPE_MAX)
			housekeeping_setup_type(type, housekeeping_staging);
	} else {
		/* Second setup call ("nohz_full=" after "isolcpus=" or the reverse) */
		enum hk_type type;
		unsigned long iter_flags = flags & housekeeping.flags;

		for_each_set_bit(type, &iter_flags, HK_TYPE_MAX) {
			if (!cpumask_equal(housekeeping_staging,
					   housekeeping.cpumasks[type])) {
				pr_warn("Housekeeping: nohz_full= must match isolcpus=\n");
				goto free_housekeeping_staging;
			}
		}

		iter_flags = flags & ~housekeeping.flags;

		for_each_set_bit(type, &iter_flags, HK_TYPE_MAX)
			housekeeping_setup_type(type, housekeeping_staging);
	}

	if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK))
		tick_nohz_full_setup(non_housekeeping_mask);

	housekeeping.flags |= flags;
	err = 1;

free_housekeeping_staging:
	free_bootmem_cpumask_var(housekeeping_staging);
free_non_housekeeping_mask:
	free_bootmem_cpumask_var(non_housekeeping_mask);

	return err;
}

static int __init housekeeping_nohz_full_setup(char *str)
{
	unsigned long flags;

	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
		HK_FLAG_MISC | HK_FLAG_KTHREAD;

	return housekeeping_setup(str, flags);
}
__setup("nohz_full=", housekeeping_nohz_full_setup);

static int __init housekeeping_isolcpus_setup(char *str)
{
	unsigned long flags = 0;
	bool illegal = false;
	char *par;
	int len;

	while (isalpha(*str)) {
		if (!strncmp(str, "nohz,", 5)) {
			str += 5;
			flags |= HK_FLAG_TICK;
			continue;
		}

		if (!strncmp(str, "domain,", 7)) {
			str += 7;
			flags |= HK_FLAG_DOMAIN;
			continue;
		}

		if (!strncmp(str, "managed_irq,", 12)) {
			str += 12;
			flags |= HK_FLAG_MANAGED_IRQ;
			continue;
		}

		/*
		 * Skip unknown sub-parameter and validate that it is not
		 * containing an invalid character.
		 */
		for (par = str, len = 0; *str && *str != ','; str++, len++) {
			if (!isalpha(*str) && *str != '_')
				illegal = true;
		}

		if (illegal) {
			pr_warn("isolcpus: Invalid flag %.*s\n", len, par);
			return 0;
		}

		pr_info("isolcpus: Skipped unknown flag %.*s\n", len, par);
		str++;
	}

	/* Default behaviour for isolcpus without flags */
	if (!flags)
		flags |= HK_FLAG_DOMAIN;

	return housekeeping_setup(str, flags);
}
__setup("isolcpus=", housekeeping_isolcpus_setup);