1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * BPF extensible scheduler class: Documentation/scheduler/sched-ext.rst 4 * 5 * Built-in idle CPU tracking policy. 6 * 7 * Copyright (c) 2022 Meta Platforms, Inc. and affiliates. 8 * Copyright (c) 2022 Tejun Heo <tj@kernel.org> 9 * Copyright (c) 2022 David Vernet <dvernet@meta.com> 10 * Copyright (c) 2024 Andrea Righi <arighi@nvidia.com> 11 */ 12 #include "ext_idle.h" 13 14 /* Enable/disable built-in idle CPU selection policy */ 15 static DEFINE_STATIC_KEY_FALSE(scx_builtin_idle_enabled); 16 17 /* Enable/disable per-node idle cpumasks */ 18 static DEFINE_STATIC_KEY_FALSE(scx_builtin_idle_per_node); 19 20 #ifdef CONFIG_SMP 21 /* Enable/disable LLC aware optimizations */ 22 static DEFINE_STATIC_KEY_FALSE(scx_selcpu_topo_llc); 23 24 /* Enable/disable NUMA aware optimizations */ 25 static DEFINE_STATIC_KEY_FALSE(scx_selcpu_topo_numa); 26 27 /* 28 * cpumasks to track idle CPUs within each NUMA node. 29 * 30 * If SCX_OPS_BUILTIN_IDLE_PER_NODE is not enabled, a single global cpumask 31 * from is used to track all the idle CPUs in the system. 32 */ 33 struct scx_idle_cpus { 34 cpumask_var_t cpu; 35 cpumask_var_t smt; 36 }; 37 38 /* 39 * Global host-wide idle cpumasks (used when SCX_OPS_BUILTIN_IDLE_PER_NODE 40 * is not enabled). 41 */ 42 static struct scx_idle_cpus scx_idle_global_masks; 43 44 /* 45 * Per-node idle cpumasks. 46 */ 47 static struct scx_idle_cpus **scx_idle_node_masks; 48 49 /* 50 * Local per-CPU cpumasks (used to generate temporary idle cpumasks). 51 */ 52 static DEFINE_PER_CPU(cpumask_var_t, local_idle_cpumask); 53 static DEFINE_PER_CPU(cpumask_var_t, local_llc_idle_cpumask); 54 static DEFINE_PER_CPU(cpumask_var_t, local_numa_idle_cpumask); 55 56 /* 57 * Return the idle masks associated to a target @node. 58 * 59 * NUMA_NO_NODE identifies the global idle cpumask. 60 */ 61 static struct scx_idle_cpus *idle_cpumask(int node) 62 { 63 return node == NUMA_NO_NODE ? &scx_idle_global_masks : scx_idle_node_masks[node]; 64 } 65 66 /* 67 * Returns the NUMA node ID associated with a @cpu, or NUMA_NO_NODE if 68 * per-node idle cpumasks are disabled. 69 */ 70 static int scx_cpu_node_if_enabled(int cpu) 71 { 72 if (!static_branch_maybe(CONFIG_NUMA, &scx_builtin_idle_per_node)) 73 return NUMA_NO_NODE; 74 75 return cpu_to_node(cpu); 76 } 77 78 bool scx_idle_test_and_clear_cpu(int cpu) 79 { 80 int node = scx_cpu_node_if_enabled(cpu); 81 struct cpumask *idle_cpus = idle_cpumask(node)->cpu; 82 83 #ifdef CONFIG_SCHED_SMT 84 /* 85 * SMT mask should be cleared whether we can claim @cpu or not. The SMT 86 * cluster is not wholly idle either way. This also prevents 87 * scx_pick_idle_cpu() from getting caught in an infinite loop. 88 */ 89 if (sched_smt_active()) { 90 const struct cpumask *smt = cpu_smt_mask(cpu); 91 struct cpumask *idle_smts = idle_cpumask(node)->smt; 92 93 /* 94 * If offline, @cpu is not its own sibling and 95 * scx_pick_idle_cpu() can get caught in an infinite loop as 96 * @cpu is never cleared from the idle SMT mask. Ensure that 97 * @cpu is eventually cleared. 98 * 99 * NOTE: Use cpumask_intersects() and cpumask_test_cpu() to 100 * reduce memory writes, which may help alleviate cache 101 * coherence pressure. 102 */ 103 if (cpumask_intersects(smt, idle_smts)) 104 cpumask_andnot(idle_smts, idle_smts, smt); 105 else if (cpumask_test_cpu(cpu, idle_smts)) 106 __cpumask_clear_cpu(cpu, idle_smts); 107 } 108 #endif 109 110 return cpumask_test_and_clear_cpu(cpu, idle_cpus); 111 } 112 113 /* 114 * Pick an idle CPU in a specific NUMA node. 115 */ 116 static s32 pick_idle_cpu_in_node(const struct cpumask *cpus_allowed, int node, u64 flags) 117 { 118 int cpu; 119 120 retry: 121 if (sched_smt_active()) { 122 cpu = cpumask_any_and_distribute(idle_cpumask(node)->smt, cpus_allowed); 123 if (cpu < nr_cpu_ids) 124 goto found; 125 126 if (flags & SCX_PICK_IDLE_CORE) 127 return -EBUSY; 128 } 129 130 cpu = cpumask_any_and_distribute(idle_cpumask(node)->cpu, cpus_allowed); 131 if (cpu >= nr_cpu_ids) 132 return -EBUSY; 133 134 found: 135 if (scx_idle_test_and_clear_cpu(cpu)) 136 return cpu; 137 else 138 goto retry; 139 } 140 141 /* 142 * Tracks nodes that have not yet been visited when searching for an idle 143 * CPU across all available nodes. 144 */ 145 static DEFINE_PER_CPU(nodemask_t, per_cpu_unvisited); 146 147 /* 148 * Search for an idle CPU across all nodes, excluding @node. 149 */ 150 static s32 pick_idle_cpu_from_online_nodes(const struct cpumask *cpus_allowed, int node, u64 flags) 151 { 152 nodemask_t *unvisited; 153 s32 cpu = -EBUSY; 154 155 preempt_disable(); 156 unvisited = this_cpu_ptr(&per_cpu_unvisited); 157 158 /* 159 * Restrict the search to the online nodes (excluding the current 160 * node that has been visited already). 161 */ 162 nodes_copy(*unvisited, node_states[N_ONLINE]); 163 node_clear(node, *unvisited); 164 165 /* 166 * Traverse all nodes in order of increasing distance, starting 167 * from @node. 168 * 169 * This loop is O(N^2), with N being the amount of NUMA nodes, 170 * which might be quite expensive in large NUMA systems. However, 171 * this complexity comes into play only when a scheduler enables 172 * SCX_OPS_BUILTIN_IDLE_PER_NODE and it's requesting an idle CPU 173 * without specifying a target NUMA node, so it shouldn't be a 174 * bottleneck is most cases. 175 * 176 * As a future optimization we may want to cache the list of nodes 177 * in a per-node array, instead of actually traversing them every 178 * time. 179 */ 180 for_each_node_numadist(node, *unvisited) { 181 cpu = pick_idle_cpu_in_node(cpus_allowed, node, flags); 182 if (cpu >= 0) 183 break; 184 } 185 preempt_enable(); 186 187 return cpu; 188 } 189 190 /* 191 * Find an idle CPU in the system, starting from @node. 192 */ 193 s32 scx_pick_idle_cpu(const struct cpumask *cpus_allowed, int node, u64 flags) 194 { 195 s32 cpu; 196 197 /* 198 * Always search in the starting node first (this is an 199 * optimization that can save some cycles even when the search is 200 * not limited to a single node). 201 */ 202 cpu = pick_idle_cpu_in_node(cpus_allowed, node, flags); 203 if (cpu >= 0) 204 return cpu; 205 206 /* 207 * Stop the search if we are using only a single global cpumask 208 * (NUMA_NO_NODE) or if the search is restricted to the first node 209 * only. 210 */ 211 if (node == NUMA_NO_NODE || flags & SCX_PICK_IDLE_IN_NODE) 212 return -EBUSY; 213 214 /* 215 * Extend the search to the other online nodes. 216 */ 217 return pick_idle_cpu_from_online_nodes(cpus_allowed, node, flags); 218 } 219 220 /* 221 * Return the amount of CPUs in the same LLC domain of @cpu (or zero if the LLC 222 * domain is not defined). 223 */ 224 static unsigned int llc_weight(s32 cpu) 225 { 226 struct sched_domain *sd; 227 228 sd = rcu_dereference(per_cpu(sd_llc, cpu)); 229 if (!sd) 230 return 0; 231 232 return sd->span_weight; 233 } 234 235 /* 236 * Return the cpumask representing the LLC domain of @cpu (or NULL if the LLC 237 * domain is not defined). 238 */ 239 static struct cpumask *llc_span(s32 cpu) 240 { 241 struct sched_domain *sd; 242 243 sd = rcu_dereference(per_cpu(sd_llc, cpu)); 244 if (!sd) 245 return 0; 246 247 return sched_domain_span(sd); 248 } 249 250 /* 251 * Return the amount of CPUs in the same NUMA domain of @cpu (or zero if the 252 * NUMA domain is not defined). 253 */ 254 static unsigned int numa_weight(s32 cpu) 255 { 256 struct sched_domain *sd; 257 struct sched_group *sg; 258 259 sd = rcu_dereference(per_cpu(sd_numa, cpu)); 260 if (!sd) 261 return 0; 262 sg = sd->groups; 263 if (!sg) 264 return 0; 265 266 return sg->group_weight; 267 } 268 269 /* 270 * Return the cpumask representing the NUMA domain of @cpu (or NULL if the NUMA 271 * domain is not defined). 272 */ 273 static struct cpumask *numa_span(s32 cpu) 274 { 275 struct sched_domain *sd; 276 struct sched_group *sg; 277 278 sd = rcu_dereference(per_cpu(sd_numa, cpu)); 279 if (!sd) 280 return NULL; 281 sg = sd->groups; 282 if (!sg) 283 return NULL; 284 285 return sched_group_span(sg); 286 } 287 288 /* 289 * Return true if the LLC domains do not perfectly overlap with the NUMA 290 * domains, false otherwise. 291 */ 292 static bool llc_numa_mismatch(void) 293 { 294 int cpu; 295 296 /* 297 * We need to scan all online CPUs to verify whether their scheduling 298 * domains overlap. 299 * 300 * While it is rare to encounter architectures with asymmetric NUMA 301 * topologies, CPU hotplugging or virtualized environments can result 302 * in asymmetric configurations. 303 * 304 * For example: 305 * 306 * NUMA 0: 307 * - LLC 0: cpu0..cpu7 308 * - LLC 1: cpu8..cpu15 [offline] 309 * 310 * NUMA 1: 311 * - LLC 0: cpu16..cpu23 312 * - LLC 1: cpu24..cpu31 313 * 314 * In this case, if we only check the first online CPU (cpu0), we might 315 * incorrectly assume that the LLC and NUMA domains are fully 316 * overlapping, which is incorrect (as NUMA 1 has two distinct LLC 317 * domains). 318 */ 319 for_each_online_cpu(cpu) 320 if (llc_weight(cpu) != numa_weight(cpu)) 321 return true; 322 323 return false; 324 } 325 326 /* 327 * Initialize topology-aware scheduling. 328 * 329 * Detect if the system has multiple LLC or multiple NUMA domains and enable 330 * cache-aware / NUMA-aware scheduling optimizations in the default CPU idle 331 * selection policy. 332 * 333 * Assumption: the kernel's internal topology representation assumes that each 334 * CPU belongs to a single LLC domain, and that each LLC domain is entirely 335 * contained within a single NUMA node. 336 */ 337 void scx_idle_update_selcpu_topology(struct sched_ext_ops *ops) 338 { 339 bool enable_llc = false, enable_numa = false; 340 unsigned int nr_cpus; 341 s32 cpu = cpumask_first(cpu_online_mask); 342 343 /* 344 * Enable LLC domain optimization only when there are multiple LLC 345 * domains among the online CPUs. If all online CPUs are part of a 346 * single LLC domain, the idle CPU selection logic can choose any 347 * online CPU without bias. 348 * 349 * Note that it is sufficient to check the LLC domain of the first 350 * online CPU to determine whether a single LLC domain includes all 351 * CPUs. 352 */ 353 rcu_read_lock(); 354 nr_cpus = llc_weight(cpu); 355 if (nr_cpus > 0) { 356 if (nr_cpus < num_online_cpus()) 357 enable_llc = true; 358 pr_debug("sched_ext: LLC=%*pb weight=%u\n", 359 cpumask_pr_args(llc_span(cpu)), llc_weight(cpu)); 360 } 361 362 /* 363 * Enable NUMA optimization only when there are multiple NUMA domains 364 * among the online CPUs and the NUMA domains don't perfectly overlaps 365 * with the LLC domains. 366 * 367 * If all CPUs belong to the same NUMA node and the same LLC domain, 368 * enabling both NUMA and LLC optimizations is unnecessary, as checking 369 * for an idle CPU in the same domain twice is redundant. 370 * 371 * If SCX_OPS_BUILTIN_IDLE_PER_NODE is enabled ignore the NUMA 372 * optimization, as we would naturally select idle CPUs within 373 * specific NUMA nodes querying the corresponding per-node cpumask. 374 */ 375 if (!(ops->flags & SCX_OPS_BUILTIN_IDLE_PER_NODE)) { 376 nr_cpus = numa_weight(cpu); 377 if (nr_cpus > 0) { 378 if (nr_cpus < num_online_cpus() && llc_numa_mismatch()) 379 enable_numa = true; 380 pr_debug("sched_ext: NUMA=%*pb weight=%u\n", 381 cpumask_pr_args(numa_span(cpu)), nr_cpus); 382 } 383 } 384 rcu_read_unlock(); 385 386 pr_debug("sched_ext: LLC idle selection %s\n", 387 str_enabled_disabled(enable_llc)); 388 pr_debug("sched_ext: NUMA idle selection %s\n", 389 str_enabled_disabled(enable_numa)); 390 391 if (enable_llc) 392 static_branch_enable_cpuslocked(&scx_selcpu_topo_llc); 393 else 394 static_branch_disable_cpuslocked(&scx_selcpu_topo_llc); 395 if (enable_numa) 396 static_branch_enable_cpuslocked(&scx_selcpu_topo_numa); 397 else 398 static_branch_disable_cpuslocked(&scx_selcpu_topo_numa); 399 } 400 401 /* 402 * Return true if @p can run on all possible CPUs, false otherwise. 403 */ 404 static inline bool task_affinity_all(const struct task_struct *p) 405 { 406 return p->nr_cpus_allowed >= num_possible_cpus(); 407 } 408 409 /* 410 * Built-in CPU idle selection policy: 411 * 412 * 1. Prioritize full-idle cores: 413 * - always prioritize CPUs from fully idle cores (both logical CPUs are 414 * idle) to avoid interference caused by SMT. 415 * 416 * 2. Reuse the same CPU: 417 * - prefer the last used CPU to take advantage of cached data (L1, L2) and 418 * branch prediction optimizations. 419 * 420 * 3. Pick a CPU within the same LLC (Last-Level Cache): 421 * - if the above conditions aren't met, pick a CPU that shares the same 422 * LLC, if the LLC domain is a subset of @cpus_allowed, to maintain 423 * cache locality. 424 * 425 * 4. Pick a CPU within the same NUMA node, if enabled: 426 * - choose a CPU from the same NUMA node, if the node cpumask is a 427 * subset of @cpus_allowed, to reduce memory access latency. 428 * 429 * 5. Pick any idle CPU within the @cpus_allowed domain. 430 * 431 * Step 3 and 4 are performed only if the system has, respectively, 432 * multiple LLCs / multiple NUMA nodes (see scx_selcpu_topo_llc and 433 * scx_selcpu_topo_numa) and they don't contain the same subset of CPUs. 434 * 435 * If %SCX_OPS_BUILTIN_IDLE_PER_NODE is enabled, the search will always 436 * begin in @prev_cpu's node and proceed to other nodes in order of 437 * increasing distance. 438 * 439 * Return the picked CPU if idle, or a negative value otherwise. 440 * 441 * NOTE: tasks that can only run on 1 CPU are excluded by this logic, because 442 * we never call ops.select_cpu() for them, see select_task_rq(). 443 */ 444 s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, 445 const struct cpumask *cpus_allowed, u64 flags) 446 { 447 const struct cpumask *llc_cpus = NULL, *numa_cpus = NULL; 448 const struct cpumask *allowed = cpus_allowed ?: p->cpus_ptr; 449 int node = scx_cpu_node_if_enabled(prev_cpu); 450 s32 cpu; 451 452 preempt_disable(); 453 454 /* 455 * Determine the subset of CPUs usable by @p within @cpus_allowed. 456 */ 457 if (allowed != p->cpus_ptr) { 458 struct cpumask *local_cpus = this_cpu_cpumask_var_ptr(local_idle_cpumask); 459 460 if (task_affinity_all(p)) { 461 allowed = cpus_allowed; 462 } else if (cpumask_and(local_cpus, cpus_allowed, p->cpus_ptr)) { 463 allowed = local_cpus; 464 } else { 465 cpu = -EBUSY; 466 goto out_enable; 467 } 468 469 /* 470 * If @prev_cpu is not in the allowed CPUs, skip topology 471 * optimizations and try to pick any idle CPU usable by the 472 * task. 473 * 474 * If %SCX_OPS_BUILTIN_IDLE_PER_NODE is enabled, prioritize 475 * the current node, as it may optimize some waker->wakee 476 * workloads. 477 */ 478 if (!cpumask_test_cpu(prev_cpu, allowed)) { 479 node = scx_cpu_node_if_enabled(smp_processor_id()); 480 cpu = scx_pick_idle_cpu(allowed, node, flags); 481 goto out_enable; 482 } 483 } 484 485 /* 486 * This is necessary to protect llc_cpus. 487 */ 488 rcu_read_lock(); 489 490 /* 491 * Determine the subset of CPUs that the task can use in its 492 * current LLC and node. 493 * 494 * If the task can run on all CPUs, use the node and LLC cpumasks 495 * directly. 496 */ 497 if (static_branch_maybe(CONFIG_NUMA, &scx_selcpu_topo_numa)) { 498 struct cpumask *local_cpus = this_cpu_cpumask_var_ptr(local_numa_idle_cpumask); 499 const struct cpumask *cpus = numa_span(prev_cpu); 500 501 if (allowed == p->cpus_ptr && task_affinity_all(p)) 502 numa_cpus = cpus; 503 else if (cpus && cpumask_and(local_cpus, allowed, cpus)) 504 numa_cpus = local_cpus; 505 } 506 507 if (static_branch_maybe(CONFIG_SCHED_MC, &scx_selcpu_topo_llc)) { 508 struct cpumask *local_cpus = this_cpu_cpumask_var_ptr(local_llc_idle_cpumask); 509 const struct cpumask *cpus = llc_span(prev_cpu); 510 511 if (allowed == p->cpus_ptr && task_affinity_all(p)) 512 llc_cpus = cpus; 513 else if (cpus && cpumask_and(local_cpus, allowed, cpus)) 514 llc_cpus = local_cpus; 515 } 516 517 /* 518 * If WAKE_SYNC, try to migrate the wakee to the waker's CPU. 519 */ 520 if (wake_flags & SCX_WAKE_SYNC) { 521 int waker_node; 522 523 /* 524 * If the waker's CPU is cache affine and prev_cpu is idle, 525 * then avoid a migration. 526 */ 527 cpu = smp_processor_id(); 528 if (cpus_share_cache(cpu, prev_cpu) && 529 scx_idle_test_and_clear_cpu(prev_cpu)) { 530 cpu = prev_cpu; 531 goto out_unlock; 532 } 533 534 /* 535 * If the waker's local DSQ is empty, and the system is under 536 * utilized, try to wake up @p to the local DSQ of the waker. 537 * 538 * Checking only for an empty local DSQ is insufficient as it 539 * could give the wakee an unfair advantage when the system is 540 * oversaturated. 541 * 542 * Checking only for the presence of idle CPUs is also 543 * insufficient as the local DSQ of the waker could have tasks 544 * piled up on it even if there is an idle core elsewhere on 545 * the system. 546 */ 547 waker_node = cpu_to_node(cpu); 548 if (!(current->flags & PF_EXITING) && 549 cpu_rq(cpu)->scx.local_dsq.nr == 0 && 550 (!(flags & SCX_PICK_IDLE_IN_NODE) || (waker_node == node)) && 551 !cpumask_empty(idle_cpumask(waker_node)->cpu)) { 552 if (cpumask_test_cpu(cpu, allowed)) 553 goto out_unlock; 554 } 555 } 556 557 /* 558 * If CPU has SMT, any wholly idle CPU is likely a better pick than 559 * partially idle @prev_cpu. 560 */ 561 if (sched_smt_active()) { 562 /* 563 * Keep using @prev_cpu if it's part of a fully idle core. 564 */ 565 if (cpumask_test_cpu(prev_cpu, idle_cpumask(node)->smt) && 566 scx_idle_test_and_clear_cpu(prev_cpu)) { 567 cpu = prev_cpu; 568 goto out_unlock; 569 } 570 571 /* 572 * Search for any fully idle core in the same LLC domain. 573 */ 574 if (llc_cpus) { 575 cpu = pick_idle_cpu_in_node(llc_cpus, node, SCX_PICK_IDLE_CORE); 576 if (cpu >= 0) 577 goto out_unlock; 578 } 579 580 /* 581 * Search for any fully idle core in the same NUMA node. 582 */ 583 if (numa_cpus) { 584 cpu = pick_idle_cpu_in_node(numa_cpus, node, SCX_PICK_IDLE_CORE); 585 if (cpu >= 0) 586 goto out_unlock; 587 } 588 589 /* 590 * Search for any full-idle core usable by the task. 591 * 592 * If the node-aware idle CPU selection policy is enabled 593 * (%SCX_OPS_BUILTIN_IDLE_PER_NODE), the search will always 594 * begin in prev_cpu's node and proceed to other nodes in 595 * order of increasing distance. 596 */ 597 cpu = scx_pick_idle_cpu(allowed, node, flags | SCX_PICK_IDLE_CORE); 598 if (cpu >= 0) 599 goto out_unlock; 600 601 /* 602 * Give up if we're strictly looking for a full-idle SMT 603 * core. 604 */ 605 if (flags & SCX_PICK_IDLE_CORE) { 606 cpu = -EBUSY; 607 goto out_unlock; 608 } 609 } 610 611 /* 612 * Use @prev_cpu if it's idle. 613 */ 614 if (scx_idle_test_and_clear_cpu(prev_cpu)) { 615 cpu = prev_cpu; 616 goto out_unlock; 617 } 618 619 /* 620 * Search for any idle CPU in the same LLC domain. 621 */ 622 if (llc_cpus) { 623 cpu = pick_idle_cpu_in_node(llc_cpus, node, 0); 624 if (cpu >= 0) 625 goto out_unlock; 626 } 627 628 /* 629 * Search for any idle CPU in the same NUMA node. 630 */ 631 if (numa_cpus) { 632 cpu = pick_idle_cpu_in_node(numa_cpus, node, 0); 633 if (cpu >= 0) 634 goto out_unlock; 635 } 636 637 /* 638 * Search for any idle CPU usable by the task. 639 * 640 * If the node-aware idle CPU selection policy is enabled 641 * (%SCX_OPS_BUILTIN_IDLE_PER_NODE), the search will always begin 642 * in prev_cpu's node and proceed to other nodes in order of 643 * increasing distance. 644 */ 645 cpu = scx_pick_idle_cpu(allowed, node, flags); 646 647 out_unlock: 648 rcu_read_unlock(); 649 out_enable: 650 preempt_enable(); 651 652 return cpu; 653 } 654 655 /* 656 * Initialize global and per-node idle cpumasks. 657 */ 658 void scx_idle_init_masks(void) 659 { 660 int i; 661 662 /* Allocate global idle cpumasks */ 663 BUG_ON(!alloc_cpumask_var(&scx_idle_global_masks.cpu, GFP_KERNEL)); 664 BUG_ON(!alloc_cpumask_var(&scx_idle_global_masks.smt, GFP_KERNEL)); 665 666 /* Allocate per-node idle cpumasks */ 667 scx_idle_node_masks = kcalloc(num_possible_nodes(), 668 sizeof(*scx_idle_node_masks), GFP_KERNEL); 669 BUG_ON(!scx_idle_node_masks); 670 671 for_each_node(i) { 672 scx_idle_node_masks[i] = kzalloc_node(sizeof(**scx_idle_node_masks), 673 GFP_KERNEL, i); 674 BUG_ON(!scx_idle_node_masks[i]); 675 676 BUG_ON(!alloc_cpumask_var_node(&scx_idle_node_masks[i]->cpu, GFP_KERNEL, i)); 677 BUG_ON(!alloc_cpumask_var_node(&scx_idle_node_masks[i]->smt, GFP_KERNEL, i)); 678 } 679 680 /* Allocate local per-cpu idle cpumasks */ 681 for_each_possible_cpu(i) { 682 BUG_ON(!alloc_cpumask_var_node(&per_cpu(local_idle_cpumask, i), 683 GFP_KERNEL, cpu_to_node(i))); 684 BUG_ON(!alloc_cpumask_var_node(&per_cpu(local_llc_idle_cpumask, i), 685 GFP_KERNEL, cpu_to_node(i))); 686 BUG_ON(!alloc_cpumask_var_node(&per_cpu(local_numa_idle_cpumask, i), 687 GFP_KERNEL, cpu_to_node(i))); 688 } 689 } 690 691 static void update_builtin_idle(int cpu, bool idle) 692 { 693 int node = scx_cpu_node_if_enabled(cpu); 694 struct cpumask *idle_cpus = idle_cpumask(node)->cpu; 695 696 assign_cpu(cpu, idle_cpus, idle); 697 698 #ifdef CONFIG_SCHED_SMT 699 if (sched_smt_active()) { 700 const struct cpumask *smt = cpu_smt_mask(cpu); 701 struct cpumask *idle_smts = idle_cpumask(node)->smt; 702 703 if (idle) { 704 /* 705 * idle_smt handling is racy but that's fine as it's 706 * only for optimization and self-correcting. 707 */ 708 if (!cpumask_subset(smt, idle_cpus)) 709 return; 710 cpumask_or(idle_smts, idle_smts, smt); 711 } else { 712 cpumask_andnot(idle_smts, idle_smts, smt); 713 } 714 } 715 #endif 716 } 717 718 /* 719 * Update the idle state of a CPU to @idle. 720 * 721 * If @do_notify is true, ops.update_idle() is invoked to notify the scx 722 * scheduler of an actual idle state transition (idle to busy or vice 723 * versa). If @do_notify is false, only the idle state in the idle masks is 724 * refreshed without invoking ops.update_idle(). 725 * 726 * This distinction is necessary, because an idle CPU can be "reserved" and 727 * awakened via scx_bpf_pick_idle_cpu() + scx_bpf_kick_cpu(), marking it as 728 * busy even if no tasks are dispatched. In this case, the CPU may return 729 * to idle without a true state transition. Refreshing the idle masks 730 * without invoking ops.update_idle() ensures accurate idle state tracking 731 * while avoiding unnecessary updates and maintaining balanced state 732 * transitions. 733 */ 734 void __scx_update_idle(struct rq *rq, bool idle, bool do_notify) 735 { 736 struct scx_sched *sch = scx_root; 737 int cpu = cpu_of(rq); 738 739 lockdep_assert_rq_held(rq); 740 741 /* 742 * Update the idle masks: 743 * - for real idle transitions (do_notify == true) 744 * - for idle-to-idle transitions (indicated by the previous task 745 * being the idle thread, managed by pick_task_idle()) 746 * 747 * Skip updating idle masks if the previous task is not the idle 748 * thread, since set_next_task_idle() has already handled it when 749 * transitioning from a task to the idle thread (calling this 750 * function with do_notify == true). 751 * 752 * In this way we can avoid updating the idle masks twice, 753 * unnecessarily. 754 */ 755 if (static_branch_likely(&scx_builtin_idle_enabled)) 756 if (do_notify || is_idle_task(rq->curr)) 757 update_builtin_idle(cpu, idle); 758 759 /* 760 * Trigger ops.update_idle() only when transitioning from a task to 761 * the idle thread and vice versa. 762 * 763 * Idle transitions are indicated by do_notify being set to true, 764 * managed by put_prev_task_idle()/set_next_task_idle(). 765 * 766 * This must come after builtin idle update so that BPF schedulers can 767 * create interlocking between ops.update_idle() and ops.enqueue() - 768 * either enqueue() sees the idle bit or update_idle() sees the task 769 * that enqueue() queued. 770 */ 771 if (SCX_HAS_OP(sch, update_idle) && do_notify && !scx_rq_bypassing(rq)) 772 SCX_CALL_OP(sch, SCX_KF_REST, update_idle, rq, cpu_of(rq), idle); 773 } 774 775 static void reset_idle_masks(struct sched_ext_ops *ops) 776 { 777 int node; 778 779 /* 780 * Consider all online cpus idle. Should converge to the actual state 781 * quickly. 782 */ 783 if (!(ops->flags & SCX_OPS_BUILTIN_IDLE_PER_NODE)) { 784 cpumask_copy(idle_cpumask(NUMA_NO_NODE)->cpu, cpu_online_mask); 785 cpumask_copy(idle_cpumask(NUMA_NO_NODE)->smt, cpu_online_mask); 786 return; 787 } 788 789 for_each_node(node) { 790 const struct cpumask *node_mask = cpumask_of_node(node); 791 792 cpumask_and(idle_cpumask(node)->cpu, cpu_online_mask, node_mask); 793 cpumask_and(idle_cpumask(node)->smt, cpu_online_mask, node_mask); 794 } 795 } 796 #endif /* CONFIG_SMP */ 797 798 void scx_idle_enable(struct sched_ext_ops *ops) 799 { 800 if (!ops->update_idle || (ops->flags & SCX_OPS_KEEP_BUILTIN_IDLE)) 801 static_branch_enable_cpuslocked(&scx_builtin_idle_enabled); 802 else 803 static_branch_disable_cpuslocked(&scx_builtin_idle_enabled); 804 805 if (ops->flags & SCX_OPS_BUILTIN_IDLE_PER_NODE) 806 static_branch_enable_cpuslocked(&scx_builtin_idle_per_node); 807 else 808 static_branch_disable_cpuslocked(&scx_builtin_idle_per_node); 809 810 #ifdef CONFIG_SMP 811 reset_idle_masks(ops); 812 #endif 813 } 814 815 void scx_idle_disable(void) 816 { 817 static_branch_disable(&scx_builtin_idle_enabled); 818 static_branch_disable(&scx_builtin_idle_per_node); 819 } 820 821 /******************************************************************************** 822 * Helpers that can be called from the BPF scheduler. 823 */ 824 825 static int validate_node(int node) 826 { 827 if (!static_branch_likely(&scx_builtin_idle_per_node)) { 828 scx_kf_error("per-node idle tracking is disabled"); 829 return -EOPNOTSUPP; 830 } 831 832 /* Return no entry for NUMA_NO_NODE (not a critical scx error) */ 833 if (node == NUMA_NO_NODE) 834 return -ENOENT; 835 836 /* Make sure node is in a valid range */ 837 if (node < 0 || node >= nr_node_ids) { 838 scx_kf_error("invalid node %d", node); 839 return -EINVAL; 840 } 841 842 /* Make sure the node is part of the set of possible nodes */ 843 if (!node_possible(node)) { 844 scx_kf_error("unavailable node %d", node); 845 return -EINVAL; 846 } 847 848 return node; 849 } 850 851 __bpf_kfunc_start_defs(); 852 853 static bool check_builtin_idle_enabled(void) 854 { 855 if (static_branch_likely(&scx_builtin_idle_enabled)) 856 return true; 857 858 scx_kf_error("built-in idle tracking is disabled"); 859 return false; 860 } 861 862 s32 select_cpu_from_kfunc(struct task_struct *p, s32 prev_cpu, u64 wake_flags, 863 const struct cpumask *allowed, u64 flags) 864 { 865 struct rq *rq; 866 struct rq_flags rf; 867 s32 cpu; 868 869 if (!kf_cpu_valid(prev_cpu, NULL)) 870 return -EINVAL; 871 872 if (!check_builtin_idle_enabled()) 873 return -EBUSY; 874 875 /* 876 * If called from an unlocked context, acquire the task's rq lock, 877 * so that we can safely access p->cpus_ptr and p->nr_cpus_allowed. 878 * 879 * Otherwise, allow to use this kfunc only from ops.select_cpu() 880 * and ops.select_enqueue(). 881 */ 882 if (scx_kf_allowed_if_unlocked()) { 883 rq = task_rq_lock(p, &rf); 884 } else { 885 if (!scx_kf_allowed(SCX_KF_SELECT_CPU | SCX_KF_ENQUEUE)) 886 return -EPERM; 887 rq = scx_locked_rq(); 888 } 889 890 /* 891 * Validate locking correctness to access p->cpus_ptr and 892 * p->nr_cpus_allowed: if we're holding an rq lock, we're safe; 893 * otherwise, assert that p->pi_lock is held. 894 */ 895 if (!rq) 896 lockdep_assert_held(&p->pi_lock); 897 898 #ifdef CONFIG_SMP 899 /* 900 * This may also be called from ops.enqueue(), so we need to handle 901 * per-CPU tasks as well. For these tasks, we can skip all idle CPU 902 * selection optimizations and simply check whether the previously 903 * used CPU is idle and within the allowed cpumask. 904 */ 905 if (p->nr_cpus_allowed == 1) { 906 if (cpumask_test_cpu(prev_cpu, allowed ?: p->cpus_ptr) && 907 scx_idle_test_and_clear_cpu(prev_cpu)) 908 cpu = prev_cpu; 909 else 910 cpu = -EBUSY; 911 } else { 912 cpu = scx_select_cpu_dfl(p, prev_cpu, wake_flags, 913 allowed ?: p->cpus_ptr, flags); 914 } 915 #else 916 cpu = -EBUSY; 917 #endif 918 if (scx_kf_allowed_if_unlocked()) 919 task_rq_unlock(rq, p, &rf); 920 921 return cpu; 922 } 923 924 /** 925 * scx_bpf_cpu_node - Return the NUMA node the given @cpu belongs to, or 926 * trigger an error if @cpu is invalid 927 * @cpu: target CPU 928 */ 929 __bpf_kfunc int scx_bpf_cpu_node(s32 cpu) 930 { 931 #ifdef CONFIG_NUMA 932 if (!kf_cpu_valid(cpu, NULL)) 933 return NUMA_NO_NODE; 934 935 return cpu_to_node(cpu); 936 #else 937 return 0; 938 #endif 939 } 940 941 /** 942 * scx_bpf_select_cpu_dfl - The default implementation of ops.select_cpu() 943 * @p: task_struct to select a CPU for 944 * @prev_cpu: CPU @p was on previously 945 * @wake_flags: %SCX_WAKE_* flags 946 * @is_idle: out parameter indicating whether the returned CPU is idle 947 * 948 * Can be called from ops.select_cpu(), ops.enqueue(), or from an unlocked 949 * context such as a BPF test_run() call, as long as built-in CPU selection 950 * is enabled: ops.update_idle() is missing or %SCX_OPS_KEEP_BUILTIN_IDLE 951 * is set. 952 * 953 * Returns the picked CPU with *@is_idle indicating whether the picked CPU is 954 * currently idle and thus a good candidate for direct dispatching. 955 */ 956 __bpf_kfunc s32 scx_bpf_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, 957 u64 wake_flags, bool *is_idle) 958 { 959 s32 cpu; 960 961 cpu = select_cpu_from_kfunc(p, prev_cpu, wake_flags, NULL, 0); 962 if (cpu >= 0) { 963 *is_idle = true; 964 return cpu; 965 } 966 *is_idle = false; 967 968 return prev_cpu; 969 } 970 971 /** 972 * scx_bpf_select_cpu_and - Pick an idle CPU usable by task @p, 973 * prioritizing those in @cpus_allowed 974 * @p: task_struct to select a CPU for 975 * @prev_cpu: CPU @p was on previously 976 * @wake_flags: %SCX_WAKE_* flags 977 * @cpus_allowed: cpumask of allowed CPUs 978 * @flags: %SCX_PICK_IDLE* flags 979 * 980 * Can be called from ops.select_cpu(), ops.enqueue(), or from an unlocked 981 * context such as a BPF test_run() call, as long as built-in CPU selection 982 * is enabled: ops.update_idle() is missing or %SCX_OPS_KEEP_BUILTIN_IDLE 983 * is set. 984 * 985 * @p, @prev_cpu and @wake_flags match ops.select_cpu(). 986 * 987 * Returns the selected idle CPU, which will be automatically awakened upon 988 * returning from ops.select_cpu() and can be used for direct dispatch, or 989 * a negative value if no idle CPU is available. 990 */ 991 __bpf_kfunc s32 scx_bpf_select_cpu_and(struct task_struct *p, s32 prev_cpu, u64 wake_flags, 992 const struct cpumask *cpus_allowed, u64 flags) 993 { 994 return select_cpu_from_kfunc(p, prev_cpu, wake_flags, cpus_allowed, flags); 995 } 996 997 /** 998 * scx_bpf_get_idle_cpumask_node - Get a referenced kptr to the 999 * idle-tracking per-CPU cpumask of a target NUMA node. 1000 * @node: target NUMA node 1001 * 1002 * Returns an empty cpumask if idle tracking is not enabled, if @node is 1003 * not valid, or running on a UP kernel. In this case the actual error will 1004 * be reported to the BPF scheduler via scx_error(). 1005 */ 1006 __bpf_kfunc const struct cpumask *scx_bpf_get_idle_cpumask_node(int node) 1007 { 1008 node = validate_node(node); 1009 if (node < 0) 1010 return cpu_none_mask; 1011 1012 #ifdef CONFIG_SMP 1013 return idle_cpumask(node)->cpu; 1014 #else 1015 return cpu_none_mask; 1016 #endif 1017 } 1018 1019 /** 1020 * scx_bpf_get_idle_cpumask - Get a referenced kptr to the idle-tracking 1021 * per-CPU cpumask. 1022 * 1023 * Returns an empty mask if idle tracking is not enabled, or running on a 1024 * UP kernel. 1025 */ 1026 __bpf_kfunc const struct cpumask *scx_bpf_get_idle_cpumask(void) 1027 { 1028 if (static_branch_unlikely(&scx_builtin_idle_per_node)) { 1029 scx_kf_error("SCX_OPS_BUILTIN_IDLE_PER_NODE enabled"); 1030 return cpu_none_mask; 1031 } 1032 1033 if (!check_builtin_idle_enabled()) 1034 return cpu_none_mask; 1035 1036 #ifdef CONFIG_SMP 1037 return idle_cpumask(NUMA_NO_NODE)->cpu; 1038 #else 1039 return cpu_none_mask; 1040 #endif 1041 } 1042 1043 /** 1044 * scx_bpf_get_idle_smtmask_node - Get a referenced kptr to the 1045 * idle-tracking, per-physical-core cpumask of a target NUMA node. Can be 1046 * used to determine if an entire physical core is free. 1047 * @node: target NUMA node 1048 * 1049 * Returns an empty cpumask if idle tracking is not enabled, if @node is 1050 * not valid, or running on a UP kernel. In this case the actual error will 1051 * be reported to the BPF scheduler via scx_error(). 1052 */ 1053 __bpf_kfunc const struct cpumask *scx_bpf_get_idle_smtmask_node(int node) 1054 { 1055 node = validate_node(node); 1056 if (node < 0) 1057 return cpu_none_mask; 1058 1059 #ifdef CONFIG_SMP 1060 if (sched_smt_active()) 1061 return idle_cpumask(node)->smt; 1062 else 1063 return idle_cpumask(node)->cpu; 1064 #else 1065 return cpu_none_mask; 1066 #endif 1067 } 1068 1069 /** 1070 * scx_bpf_get_idle_smtmask - Get a referenced kptr to the idle-tracking, 1071 * per-physical-core cpumask. Can be used to determine if an entire physical 1072 * core is free. 1073 * 1074 * Returns an empty mask if idle tracking is not enabled, or running on a 1075 * UP kernel. 1076 */ 1077 __bpf_kfunc const struct cpumask *scx_bpf_get_idle_smtmask(void) 1078 { 1079 if (static_branch_unlikely(&scx_builtin_idle_per_node)) { 1080 scx_kf_error("SCX_OPS_BUILTIN_IDLE_PER_NODE enabled"); 1081 return cpu_none_mask; 1082 } 1083 1084 if (!check_builtin_idle_enabled()) 1085 return cpu_none_mask; 1086 1087 #ifdef CONFIG_SMP 1088 if (sched_smt_active()) 1089 return idle_cpumask(NUMA_NO_NODE)->smt; 1090 else 1091 return idle_cpumask(NUMA_NO_NODE)->cpu; 1092 #else 1093 return cpu_none_mask; 1094 #endif 1095 } 1096 1097 /** 1098 * scx_bpf_put_idle_cpumask - Release a previously acquired referenced kptr to 1099 * either the percpu, or SMT idle-tracking cpumask. 1100 * @idle_mask: &cpumask to use 1101 */ 1102 __bpf_kfunc void scx_bpf_put_idle_cpumask(const struct cpumask *idle_mask) 1103 { 1104 /* 1105 * Empty function body because we aren't actually acquiring or releasing 1106 * a reference to a global idle cpumask, which is read-only in the 1107 * caller and is never released. The acquire / release semantics here 1108 * are just used to make the cpumask a trusted pointer in the caller. 1109 */ 1110 } 1111 1112 /** 1113 * scx_bpf_test_and_clear_cpu_idle - Test and clear @cpu's idle state 1114 * @cpu: cpu to test and clear idle for 1115 * 1116 * Returns %true if @cpu was idle and its idle state was successfully cleared. 1117 * %false otherwise. 1118 * 1119 * Unavailable if ops.update_idle() is implemented and 1120 * %SCX_OPS_KEEP_BUILTIN_IDLE is not set. 1121 */ 1122 __bpf_kfunc bool scx_bpf_test_and_clear_cpu_idle(s32 cpu) 1123 { 1124 if (!check_builtin_idle_enabled()) 1125 return false; 1126 1127 if (kf_cpu_valid(cpu, NULL)) 1128 return scx_idle_test_and_clear_cpu(cpu); 1129 else 1130 return false; 1131 } 1132 1133 /** 1134 * scx_bpf_pick_idle_cpu_node - Pick and claim an idle cpu from @node 1135 * @cpus_allowed: Allowed cpumask 1136 * @node: target NUMA node 1137 * @flags: %SCX_PICK_IDLE_* flags 1138 * 1139 * Pick and claim an idle cpu in @cpus_allowed from the NUMA node @node. 1140 * 1141 * Returns the picked idle cpu number on success, or -%EBUSY if no matching 1142 * cpu was found. 1143 * 1144 * The search starts from @node and proceeds to other online NUMA nodes in 1145 * order of increasing distance (unless SCX_PICK_IDLE_IN_NODE is specified, 1146 * in which case the search is limited to the target @node). 1147 * 1148 * Always returns an error if ops.update_idle() is implemented and 1149 * %SCX_OPS_KEEP_BUILTIN_IDLE is not set, or if 1150 * %SCX_OPS_BUILTIN_IDLE_PER_NODE is not set. 1151 */ 1152 __bpf_kfunc s32 scx_bpf_pick_idle_cpu_node(const struct cpumask *cpus_allowed, 1153 int node, u64 flags) 1154 { 1155 node = validate_node(node); 1156 if (node < 0) 1157 return node; 1158 1159 return scx_pick_idle_cpu(cpus_allowed, node, flags); 1160 } 1161 1162 /** 1163 * scx_bpf_pick_idle_cpu - Pick and claim an idle cpu 1164 * @cpus_allowed: Allowed cpumask 1165 * @flags: %SCX_PICK_IDLE_CPU_* flags 1166 * 1167 * Pick and claim an idle cpu in @cpus_allowed. Returns the picked idle cpu 1168 * number on success. -%EBUSY if no matching cpu was found. 1169 * 1170 * Idle CPU tracking may race against CPU scheduling state transitions. For 1171 * example, this function may return -%EBUSY as CPUs are transitioning into the 1172 * idle state. If the caller then assumes that there will be dispatch events on 1173 * the CPUs as they were all busy, the scheduler may end up stalling with CPUs 1174 * idling while there are pending tasks. Use scx_bpf_pick_any_cpu() and 1175 * scx_bpf_kick_cpu() to guarantee that there will be at least one dispatch 1176 * event in the near future. 1177 * 1178 * Unavailable if ops.update_idle() is implemented and 1179 * %SCX_OPS_KEEP_BUILTIN_IDLE is not set. 1180 * 1181 * Always returns an error if %SCX_OPS_BUILTIN_IDLE_PER_NODE is set, use 1182 * scx_bpf_pick_idle_cpu_node() instead. 1183 */ 1184 __bpf_kfunc s32 scx_bpf_pick_idle_cpu(const struct cpumask *cpus_allowed, 1185 u64 flags) 1186 { 1187 if (static_branch_maybe(CONFIG_NUMA, &scx_builtin_idle_per_node)) { 1188 scx_kf_error("per-node idle tracking is enabled"); 1189 return -EBUSY; 1190 } 1191 1192 if (!check_builtin_idle_enabled()) 1193 return -EBUSY; 1194 1195 return scx_pick_idle_cpu(cpus_allowed, NUMA_NO_NODE, flags); 1196 } 1197 1198 /** 1199 * scx_bpf_pick_any_cpu_node - Pick and claim an idle cpu if available 1200 * or pick any CPU from @node 1201 * @cpus_allowed: Allowed cpumask 1202 * @node: target NUMA node 1203 * @flags: %SCX_PICK_IDLE_CPU_* flags 1204 * 1205 * Pick and claim an idle cpu in @cpus_allowed. If none is available, pick any 1206 * CPU in @cpus_allowed. Guaranteed to succeed and returns the picked idle cpu 1207 * number if @cpus_allowed is not empty. -%EBUSY is returned if @cpus_allowed is 1208 * empty. 1209 * 1210 * The search starts from @node and proceeds to other online NUMA nodes in 1211 * order of increasing distance (unless %SCX_PICK_IDLE_IN_NODE is specified, 1212 * in which case the search is limited to the target @node, regardless of 1213 * the CPU idle state). 1214 * 1215 * If ops.update_idle() is implemented and %SCX_OPS_KEEP_BUILTIN_IDLE is not 1216 * set, this function can't tell which CPUs are idle and will always pick any 1217 * CPU. 1218 */ 1219 __bpf_kfunc s32 scx_bpf_pick_any_cpu_node(const struct cpumask *cpus_allowed, 1220 int node, u64 flags) 1221 { 1222 s32 cpu; 1223 1224 node = validate_node(node); 1225 if (node < 0) 1226 return node; 1227 1228 cpu = scx_pick_idle_cpu(cpus_allowed, node, flags); 1229 if (cpu >= 0) 1230 return cpu; 1231 1232 if (flags & SCX_PICK_IDLE_IN_NODE) 1233 cpu = cpumask_any_and_distribute(cpumask_of_node(node), cpus_allowed); 1234 else 1235 cpu = cpumask_any_distribute(cpus_allowed); 1236 if (cpu < nr_cpu_ids) 1237 return cpu; 1238 else 1239 return -EBUSY; 1240 } 1241 1242 /** 1243 * scx_bpf_pick_any_cpu - Pick and claim an idle cpu if available or pick any CPU 1244 * @cpus_allowed: Allowed cpumask 1245 * @flags: %SCX_PICK_IDLE_CPU_* flags 1246 * 1247 * Pick and claim an idle cpu in @cpus_allowed. If none is available, pick any 1248 * CPU in @cpus_allowed. Guaranteed to succeed and returns the picked idle cpu 1249 * number if @cpus_allowed is not empty. -%EBUSY is returned if @cpus_allowed is 1250 * empty. 1251 * 1252 * If ops.update_idle() is implemented and %SCX_OPS_KEEP_BUILTIN_IDLE is not 1253 * set, this function can't tell which CPUs are idle and will always pick any 1254 * CPU. 1255 * 1256 * Always returns an error if %SCX_OPS_BUILTIN_IDLE_PER_NODE is set, use 1257 * scx_bpf_pick_any_cpu_node() instead. 1258 */ 1259 __bpf_kfunc s32 scx_bpf_pick_any_cpu(const struct cpumask *cpus_allowed, 1260 u64 flags) 1261 { 1262 s32 cpu; 1263 1264 if (static_branch_maybe(CONFIG_NUMA, &scx_builtin_idle_per_node)) { 1265 scx_kf_error("per-node idle tracking is enabled"); 1266 return -EBUSY; 1267 } 1268 1269 if (static_branch_likely(&scx_builtin_idle_enabled)) { 1270 cpu = scx_pick_idle_cpu(cpus_allowed, NUMA_NO_NODE, flags); 1271 if (cpu >= 0) 1272 return cpu; 1273 } 1274 1275 cpu = cpumask_any_distribute(cpus_allowed); 1276 if (cpu < nr_cpu_ids) 1277 return cpu; 1278 else 1279 return -EBUSY; 1280 } 1281 1282 __bpf_kfunc_end_defs(); 1283 1284 BTF_KFUNCS_START(scx_kfunc_ids_idle) 1285 BTF_ID_FLAGS(func, scx_bpf_cpu_node) 1286 BTF_ID_FLAGS(func, scx_bpf_get_idle_cpumask_node, KF_ACQUIRE) 1287 BTF_ID_FLAGS(func, scx_bpf_get_idle_cpumask, KF_ACQUIRE) 1288 BTF_ID_FLAGS(func, scx_bpf_get_idle_smtmask_node, KF_ACQUIRE) 1289 BTF_ID_FLAGS(func, scx_bpf_get_idle_smtmask, KF_ACQUIRE) 1290 BTF_ID_FLAGS(func, scx_bpf_put_idle_cpumask, KF_RELEASE) 1291 BTF_ID_FLAGS(func, scx_bpf_test_and_clear_cpu_idle) 1292 BTF_ID_FLAGS(func, scx_bpf_pick_idle_cpu_node, KF_RCU) 1293 BTF_ID_FLAGS(func, scx_bpf_pick_idle_cpu, KF_RCU) 1294 BTF_ID_FLAGS(func, scx_bpf_pick_any_cpu_node, KF_RCU) 1295 BTF_ID_FLAGS(func, scx_bpf_pick_any_cpu, KF_RCU) 1296 BTF_ID_FLAGS(func, scx_bpf_select_cpu_and, KF_RCU) 1297 BTF_ID_FLAGS(func, scx_bpf_select_cpu_dfl, KF_RCU) 1298 BTF_KFUNCS_END(scx_kfunc_ids_idle) 1299 1300 static const struct btf_kfunc_id_set scx_kfunc_set_idle = { 1301 .owner = THIS_MODULE, 1302 .set = &scx_kfunc_ids_idle, 1303 }; 1304 1305 int scx_idle_init(void) 1306 { 1307 int ret; 1308 1309 ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &scx_kfunc_set_idle) || 1310 register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &scx_kfunc_set_idle) || 1311 register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &scx_kfunc_set_idle); 1312 1313 return ret; 1314 } 1315