1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Housekeeping management. Manage the targets for routine code that can run on 4 * any CPU: unbound workqueues, timers, kthreads and any offloadable work. 5 * 6 * Copyright (C) 2017 Red Hat, Inc., Frederic Weisbecker 7 * Copyright (C) 2017-2018 SUSE, Frederic Weisbecker 8 * 9 */ 10 #include <linux/sched/isolation.h> 11 #include "sched.h" 12 13 enum hk_flags { 14 HK_FLAG_DOMAIN = BIT(HK_TYPE_DOMAIN), 15 HK_FLAG_MANAGED_IRQ = BIT(HK_TYPE_MANAGED_IRQ), 16 HK_FLAG_KERNEL_NOISE = BIT(HK_TYPE_KERNEL_NOISE), 17 }; 18 19 DEFINE_STATIC_KEY_FALSE(housekeeping_overridden); 20 EXPORT_SYMBOL_GPL(housekeeping_overridden); 21 22 struct housekeeping { 23 cpumask_var_t cpumasks[HK_TYPE_MAX]; 24 unsigned long flags; 25 }; 26 27 static struct housekeeping housekeeping; 28 29 bool housekeeping_enabled(enum hk_type type) 30 { 31 return !!(housekeeping.flags & BIT(type)); 32 } 33 EXPORT_SYMBOL_GPL(housekeeping_enabled); 34 35 int housekeeping_any_cpu(enum hk_type type) 36 { 37 int cpu; 38 39 if (static_branch_unlikely(&housekeeping_overridden)) { 40 if (housekeeping.flags & BIT(type)) { 41 cpu = sched_numa_find_closest(housekeeping.cpumasks[type], smp_processor_id()); 42 if (cpu < nr_cpu_ids) 43 return cpu; 44 45 cpu = cpumask_any_and_distribute(housekeeping.cpumasks[type], cpu_online_mask); 46 if (likely(cpu < nr_cpu_ids)) 47 return cpu; 48 /* 49 * Unless we have another problem this can only happen 50 * at boot time before start_secondary() brings the 1st 51 * housekeeping CPU up. 52 */ 53 WARN_ON_ONCE(system_state == SYSTEM_RUNNING || 54 type != HK_TYPE_TIMER); 55 } 56 } 57 return smp_processor_id(); 58 } 59 EXPORT_SYMBOL_GPL(housekeeping_any_cpu); 60 61 const struct cpumask *housekeeping_cpumask(enum hk_type type) 62 { 63 if (static_branch_unlikely(&housekeeping_overridden)) 64 if (housekeeping.flags & BIT(type)) 65 return housekeeping.cpumasks[type]; 66 return cpu_possible_mask; 67 } 68 EXPORT_SYMBOL_GPL(housekeeping_cpumask); 69 70 void housekeeping_affine(struct task_struct *t, enum hk_type type) 71 { 72 if (static_branch_unlikely(&housekeeping_overridden)) 73 if (housekeeping.flags & BIT(type)) 74 set_cpus_allowed_ptr(t, housekeeping.cpumasks[type]); 75 } 76 EXPORT_SYMBOL_GPL(housekeeping_affine); 77 78 bool housekeeping_test_cpu(int cpu, enum hk_type type) 79 { 80 if (static_branch_unlikely(&housekeeping_overridden)) 81 if (housekeeping.flags & BIT(type)) 82 return cpumask_test_cpu(cpu, housekeeping.cpumasks[type]); 83 return true; 84 } 85 EXPORT_SYMBOL_GPL(housekeeping_test_cpu); 86 87 void __init housekeeping_init(void) 88 { 89 enum hk_type type; 90 91 if (!housekeeping.flags) 92 return; 93 94 static_branch_enable(&housekeeping_overridden); 95 96 if (housekeeping.flags & HK_FLAG_KERNEL_NOISE) 97 sched_tick_offload_init(); 98 99 for_each_set_bit(type, &housekeeping.flags, HK_TYPE_MAX) { 100 /* We need at least one CPU to handle housekeeping work */ 101 WARN_ON_ONCE(cpumask_empty(housekeeping.cpumasks[type])); 102 } 103 } 104 105 static void __init housekeeping_setup_type(enum hk_type type, 106 cpumask_var_t housekeeping_staging) 107 { 108 109 alloc_bootmem_cpumask_var(&housekeeping.cpumasks[type]); 110 cpumask_copy(housekeeping.cpumasks[type], 111 housekeeping_staging); 112 } 113 114 static int __init housekeeping_setup(char *str, unsigned long flags) 115 { 116 cpumask_var_t non_housekeeping_mask, housekeeping_staging; 117 unsigned int first_cpu; 118 int err = 0; 119 120 if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE)) { 121 if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) { 122 pr_warn("Housekeeping: nohz unsupported." 123 " Build with CONFIG_NO_HZ_FULL\n"); 124 return 0; 125 } 126 } 127 128 alloc_bootmem_cpumask_var(&non_housekeeping_mask); 129 if (cpulist_parse(str, non_housekeeping_mask) < 0) { 130 pr_warn("Housekeeping: nohz_full= or isolcpus= incorrect CPU range\n"); 131 goto free_non_housekeeping_mask; 132 } 133 134 alloc_bootmem_cpumask_var(&housekeeping_staging); 135 cpumask_andnot(housekeeping_staging, 136 cpu_possible_mask, non_housekeeping_mask); 137 138 first_cpu = cpumask_first_and(cpu_present_mask, housekeeping_staging); 139 if (first_cpu >= nr_cpu_ids || first_cpu >= setup_max_cpus) { 140 __cpumask_set_cpu(smp_processor_id(), housekeeping_staging); 141 __cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask); 142 if (!housekeeping.flags) { 143 pr_warn("Housekeeping: must include one present CPU, " 144 "using boot CPU:%d\n", smp_processor_id()); 145 } 146 } 147 148 if (cpumask_empty(non_housekeeping_mask)) 149 goto free_housekeeping_staging; 150 151 if (!housekeeping.flags) { 152 /* First setup call ("nohz_full=" or "isolcpus=") */ 153 enum hk_type type; 154 155 for_each_set_bit(type, &flags, HK_TYPE_MAX) 156 housekeeping_setup_type(type, housekeeping_staging); 157 } else { 158 /* Second setup call ("nohz_full=" after "isolcpus=" or the reverse) */ 159 enum hk_type type; 160 unsigned long iter_flags = flags & housekeeping.flags; 161 162 for_each_set_bit(type, &iter_flags, HK_TYPE_MAX) { 163 if (!cpumask_equal(housekeeping_staging, 164 housekeeping.cpumasks[type])) { 165 pr_warn("Housekeeping: nohz_full= must match isolcpus=\n"); 166 goto free_housekeeping_staging; 167 } 168 } 169 170 iter_flags = flags & ~housekeeping.flags; 171 172 for_each_set_bit(type, &iter_flags, HK_TYPE_MAX) 173 housekeeping_setup_type(type, housekeeping_staging); 174 } 175 176 if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE)) 177 tick_nohz_full_setup(non_housekeeping_mask); 178 179 housekeeping.flags |= flags; 180 err = 1; 181 182 free_housekeeping_staging: 183 free_bootmem_cpumask_var(housekeeping_staging); 184 free_non_housekeeping_mask: 185 free_bootmem_cpumask_var(non_housekeeping_mask); 186 187 return err; 188 } 189 190 static int __init housekeeping_nohz_full_setup(char *str) 191 { 192 unsigned long flags; 193 194 flags = HK_FLAG_KERNEL_NOISE; 195 196 return housekeeping_setup(str, flags); 197 } 198 __setup("nohz_full=", housekeeping_nohz_full_setup); 199 200 static int __init housekeeping_isolcpus_setup(char *str) 201 { 202 unsigned long flags = 0; 203 bool illegal = false; 204 char *par; 205 int len; 206 207 while (isalpha(*str)) { 208 /* 209 * isolcpus=nohz is equivalent to nohz_full. 210 */ 211 if (!strncmp(str, "nohz,", 5)) { 212 str += 5; 213 flags |= HK_FLAG_KERNEL_NOISE; 214 continue; 215 } 216 217 if (!strncmp(str, "domain,", 7)) { 218 str += 7; 219 flags |= HK_FLAG_DOMAIN; 220 continue; 221 } 222 223 if (!strncmp(str, "managed_irq,", 12)) { 224 str += 12; 225 flags |= HK_FLAG_MANAGED_IRQ; 226 continue; 227 } 228 229 /* 230 * Skip unknown sub-parameter and validate that it is not 231 * containing an invalid character. 232 */ 233 for (par = str, len = 0; *str && *str != ','; str++, len++) { 234 if (!isalpha(*str) && *str != '_') 235 illegal = true; 236 } 237 238 if (illegal) { 239 pr_warn("isolcpus: Invalid flag %.*s\n", len, par); 240 return 0; 241 } 242 243 pr_info("isolcpus: Skipped unknown flag %.*s\n", len, par); 244 str++; 245 } 246 247 /* Default behaviour for isolcpus without flags */ 248 if (!flags) 249 flags |= HK_FLAG_DOMAIN; 250 251 return housekeeping_setup(str, flags); 252 } 253 __setup("isolcpus=", housekeeping_isolcpus_setup); 254