4 * Processor and Memory placement constraints for sets of tasks.
6 * Copyright (C) 2003 BULL SA.
7 * Copyright (C) 2004-2007 Silicon Graphics, Inc.
8 * Copyright (C) 2006 Google, Inc
10 * Portions derived from Patrick Mochel's sysfs code.
11 * sysfs is Copyright (c) 2001-3 Patrick Mochel
13 * 2003-10-10 Written by Simon Derr.
14 * 2003-10-22 Updates by Stephen Hemminger.
15 * 2004 May-July Rework by Paul Jackson.
16 * 2006 Rework by Paul Menage to use generic cgroups
17 * 2008 Rework of the scheduler domains and CPU hotplug handling
20 * This file is subject to the terms and conditions of the GNU General Public
21 * License. See the file COPYING in the main directory of the Linux
22 * distribution for more details.
25 #include <linux/cpu.h>
26 #include <linux/cpumask.h>
27 #include <linux/cpuset.h>
28 #include <linux/err.h>
29 #include <linux/errno.h>
30 #include <linux/file.h>
32 #include <linux/init.h>
33 #include <linux/interrupt.h>
34 #include <linux/kernel.h>
35 #include <linux/kmod.h>
36 #include <linux/list.h>
37 #include <linux/mempolicy.h>
39 #include <linux/memory.h>
40 #include <linux/module.h>
41 #include <linux/mount.h>
42 #include <linux/namei.h>
43 #include <linux/pagemap.h>
44 #include <linux/proc_fs.h>
45 #include <linux/rcupdate.h>
46 #include <linux/sched.h>
47 #include <linux/seq_file.h>
48 #include <linux/security.h>
49 #include <linux/slab.h>
50 #include <linux/spinlock.h>
51 #include <linux/stat.h>
52 #include <linux/string.h>
53 #include <linux/time.h>
54 #include <linux/backing-dev.h>
55 #include <linux/sort.h>
57 #include <asm/uaccess.h>
58 #include <asm/atomic.h>
59 #include <linux/mutex.h>
60 #include <linux/workqueue.h>
61 #include <linux/cgroup.h>
64 * Tracks how many cpusets are currently defined in system.
65 * When there is only one cpuset (the root cpuset) we can
66 * short circuit some hooks.
68 int number_of_cpusets __read_mostly;
70 /* Forward declare cgroup structures */
71 struct cgroup_subsys cpuset_subsys;
74 /* See "Frequency meter" comments, below. */
77 int cnt; /* unprocessed events count */
78 int val; /* most recent output value */
79 time_t time; /* clock (secs) when val computed */
80 spinlock_t lock; /* guards read or write of above */
84 struct cgroup_subsys_state css;
86 unsigned long flags; /* "unsigned long" so bitops work */
87 cpumask_t cpus_allowed; /* CPUs allowed to tasks in cpuset */
88 nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */
90 struct cpuset *parent; /* my parent */
93 * Copy of global cpuset_mems_generation as of the most
94 * recent time this cpuset changed its mems_allowed.
98 struct fmeter fmeter; /* memory_pressure filter */
100 /* partition number for rebuild_sched_domains() */
103 /* for custom sched domain */
104 int relax_domain_level;
106 /* used for walking a cpuset heirarchy */
107 struct list_head stack_list;
110 /* Retrieve the cpuset for a cgroup */
111 static inline struct cpuset *cgroup_cs(struct cgroup *cont)
113 return container_of(cgroup_subsys_state(cont, cpuset_subsys_id),
117 /* Retrieve the cpuset for a task */
118 static inline struct cpuset *task_cs(struct task_struct *task)
120 return container_of(task_subsys_state(task, cpuset_subsys_id),
123 struct cpuset_hotplug_scanner {
124 struct cgroup_scanner scan;
128 /* bits in struct cpuset flags field */
134 CS_SCHED_LOAD_BALANCE,
139 /* convenient tests for these bits */
140 static inline int is_cpu_exclusive(const struct cpuset *cs)
142 return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
145 static inline int is_mem_exclusive(const struct cpuset *cs)
147 return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
150 static inline int is_mem_hardwall(const struct cpuset *cs)
152 return test_bit(CS_MEM_HARDWALL, &cs->flags);
155 static inline int is_sched_load_balance(const struct cpuset *cs)
157 return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
160 static inline int is_memory_migrate(const struct cpuset *cs)
162 return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
165 static inline int is_spread_page(const struct cpuset *cs)
167 return test_bit(CS_SPREAD_PAGE, &cs->flags);
170 static inline int is_spread_slab(const struct cpuset *cs)
172 return test_bit(CS_SPREAD_SLAB, &cs->flags);
176 * Increment this integer everytime any cpuset changes its
177 * mems_allowed value. Users of cpusets can track this generation
178 * number, and avoid having to lock and reload mems_allowed unless
179 * the cpuset they're using changes generation.
181 * A single, global generation is needed because cpuset_attach_task() could
182 * reattach a task to a different cpuset, which must not have its
183 * generation numbers aliased with those of that tasks previous cpuset.
185 * Generations are needed for mems_allowed because one task cannot
186 * modify another's memory placement. So we must enable every task,
187 * on every visit to __alloc_pages(), to efficiently check whether
188 * its current->cpuset->mems_allowed has changed, requiring an update
189 * of its current->mems_allowed.
191 * Since writes to cpuset_mems_generation are guarded by the cgroup lock
192 * there is no need to mark it atomic.
194 static int cpuset_mems_generation;
196 static struct cpuset top_cpuset = {
197 .flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)),
198 .cpus_allowed = CPU_MASK_ALL,
199 .mems_allowed = NODE_MASK_ALL,
203 * There are two global mutexes guarding cpuset structures. The first
204 * is the main control groups cgroup_mutex, accessed via
205 * cgroup_lock()/cgroup_unlock(). The second is the cpuset-specific
206 * callback_mutex, below. They can nest. It is ok to first take
207 * cgroup_mutex, then nest callback_mutex. We also require taking
208 * task_lock() when dereferencing a task's cpuset pointer. See "The
209 * task_lock() exception", at the end of this comment.
211 * A task must hold both mutexes to modify cpusets. If a task
212 * holds cgroup_mutex, then it blocks others wanting that mutex,
213 * ensuring that it is the only task able to also acquire callback_mutex
214 * and be able to modify cpusets. It can perform various checks on
215 * the cpuset structure first, knowing nothing will change. It can
216 * also allocate memory while just holding cgroup_mutex. While it is
217 * performing these checks, various callback routines can briefly
218 * acquire callback_mutex to query cpusets. Once it is ready to make
219 * the changes, it takes callback_mutex, blocking everyone else.
221 * Calls to the kernel memory allocator can not be made while holding
222 * callback_mutex, as that would risk double tripping on callback_mutex
223 * from one of the callbacks into the cpuset code from within
226 * If a task is only holding callback_mutex, then it has read-only
229 * The task_struct fields mems_allowed and mems_generation may only
230 * be accessed in the context of that task, so require no locks.
232 * The cpuset_common_file_read() handlers only hold callback_mutex across
233 * small pieces of code, such as when reading out possibly multi-word
234 * cpumasks and nodemasks.
236 * Accessing a task's cpuset should be done in accordance with the
237 * guidelines for accessing subsystem state in kernel/cgroup.c
240 static DEFINE_MUTEX(callback_mutex);
243 * cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist
244 * buffers. They are statically allocated to prevent using excess stack
245 * when calling cpuset_print_task_mems_allowed().
247 #define CPUSET_NAME_LEN (128)
248 #define CPUSET_NODELIST_LEN (256)
249 static char cpuset_name[CPUSET_NAME_LEN];
250 static char cpuset_nodelist[CPUSET_NODELIST_LEN];
251 static DEFINE_SPINLOCK(cpuset_buffer_lock);
254 * This is ugly, but preserves the userspace API for existing cpuset
255 * users. If someone tries to mount the "cpuset" filesystem, we
256 * silently switch it to mount "cgroup" instead
258 static int cpuset_get_sb(struct file_system_type *fs_type,
259 int flags, const char *unused_dev_name,
260 void *data, struct vfsmount *mnt)
262 struct file_system_type *cgroup_fs = get_fs_type("cgroup");
267 "release_agent=/sbin/cpuset_release_agent";
268 ret = cgroup_fs->get_sb(cgroup_fs, flags,
269 unused_dev_name, mountopts, mnt);
270 put_filesystem(cgroup_fs);
275 static struct file_system_type cpuset_fs_type = {
277 .get_sb = cpuset_get_sb,
281 * Return in *pmask the portion of a cpusets's cpus_allowed that
282 * are online. If none are online, walk up the cpuset hierarchy
283 * until we find one that does have some online cpus. If we get
284 * all the way to the top and still haven't found any online cpus,
285 * return cpu_online_map. Or if passed a NULL cs from an exit'ing
286 * task, return cpu_online_map.
288 * One way or another, we guarantee to return some non-empty subset
291 * Call with callback_mutex held.
294 static void guarantee_online_cpus(const struct cpuset *cs, cpumask_t *pmask)
296 while (cs && !cpus_intersects(cs->cpus_allowed, cpu_online_map))
299 cpus_and(*pmask, cs->cpus_allowed, cpu_online_map);
301 *pmask = cpu_online_map;
302 BUG_ON(!cpus_intersects(*pmask, cpu_online_map));
306 * Return in *pmask the portion of a cpusets's mems_allowed that
307 * are online, with memory. If none are online with memory, walk
308 * up the cpuset hierarchy until we find one that does have some
309 * online mems. If we get all the way to the top and still haven't
310 * found any online mems, return node_states[N_HIGH_MEMORY].
312 * One way or another, we guarantee to return some non-empty subset
313 * of node_states[N_HIGH_MEMORY].
315 * Call with callback_mutex held.
318 static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
320 while (cs && !nodes_intersects(cs->mems_allowed,
321 node_states[N_HIGH_MEMORY]))
324 nodes_and(*pmask, cs->mems_allowed,
325 node_states[N_HIGH_MEMORY]);
327 *pmask = node_states[N_HIGH_MEMORY];
328 BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY]));
332 * cpuset_update_task_memory_state - update task memory placement
334 * If the current tasks cpusets mems_allowed changed behind our
335 * backs, update current->mems_allowed, mems_generation and task NUMA
336 * mempolicy to the new value.
338 * Task mempolicy is updated by rebinding it relative to the
339 * current->cpuset if a task has its memory placement changed.
340 * Do not call this routine if in_interrupt().
342 * Call without callback_mutex or task_lock() held. May be
343 * called with or without cgroup_mutex held. Thanks in part to
344 * 'the_top_cpuset_hack', the task's cpuset pointer will never
345 * be NULL. This routine also might acquire callback_mutex during
348 * Reading current->cpuset->mems_generation doesn't need task_lock
349 * to guard the current->cpuset derefence, because it is guarded
350 * from concurrent freeing of current->cpuset using RCU.
352 * The rcu_dereference() is technically probably not needed,
353 * as I don't actually mind if I see a new cpuset pointer but
354 * an old value of mems_generation. However this really only
355 * matters on alpha systems using cpusets heavily. If I dropped
356 * that rcu_dereference(), it would save them a memory barrier.
357 * For all other arch's, rcu_dereference is a no-op anyway, and for
358 * alpha systems not using cpusets, another planned optimization,
359 * avoiding the rcu critical section for tasks in the root cpuset
360 * which is statically allocated, so can't vanish, will make this
361 * irrelevant. Better to use RCU as intended, than to engage in
362 * some cute trick to save a memory barrier that is impossible to
363 * test, for alpha systems using cpusets heavily, which might not
366 * This routine is needed to update the per-task mems_allowed data,
367 * within the tasks context, when it is trying to allocate memory
368 * (in various mm/mempolicy.c routines) and notices that some other
369 * task has been modifying its cpuset.
372 void cpuset_update_task_memory_state(void)
374 int my_cpusets_mem_gen;
375 struct task_struct *tsk = current;
379 my_cpusets_mem_gen = task_cs(tsk)->mems_generation;
382 if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {
383 mutex_lock(&callback_mutex);
385 cs = task_cs(tsk); /* Maybe changed when task not locked */
386 guarantee_online_mems(cs, &tsk->mems_allowed);
387 tsk->cpuset_mems_generation = cs->mems_generation;
388 if (is_spread_page(cs))
389 tsk->flags |= PF_SPREAD_PAGE;
391 tsk->flags &= ~PF_SPREAD_PAGE;
392 if (is_spread_slab(cs))
393 tsk->flags |= PF_SPREAD_SLAB;
395 tsk->flags &= ~PF_SPREAD_SLAB;
397 mutex_unlock(&callback_mutex);
398 mpol_rebind_task(tsk, &tsk->mems_allowed);
403 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
405 * One cpuset is a subset of another if all its allowed CPUs and
406 * Memory Nodes are a subset of the other, and its exclusive flags
407 * are only set if the other's are set. Call holding cgroup_mutex.
410 static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
412 return cpus_subset(p->cpus_allowed, q->cpus_allowed) &&
413 nodes_subset(p->mems_allowed, q->mems_allowed) &&
414 is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
415 is_mem_exclusive(p) <= is_mem_exclusive(q);
419 * alloc_trial_cpuset - allocate a trial cpuset
420 * @cs: the cpuset that the trial cpuset duplicates
422 static struct cpuset *alloc_trial_cpuset(const struct cpuset *cs)
424 return kmemdup(cs, sizeof(*cs), GFP_KERNEL);
428 * free_trial_cpuset - free the trial cpuset
429 * @trial: the trial cpuset to be freed
431 static void free_trial_cpuset(struct cpuset *trial)
437 * validate_change() - Used to validate that any proposed cpuset change
438 * follows the structural rules for cpusets.
440 * If we replaced the flag and mask values of the current cpuset
441 * (cur) with those values in the trial cpuset (trial), would
442 * our various subset and exclusive rules still be valid? Presumes
445 * 'cur' is the address of an actual, in-use cpuset. Operations
446 * such as list traversal that depend on the actual address of the
447 * cpuset in the list must use cur below, not trial.
449 * 'trial' is the address of bulk structure copy of cur, with
450 * perhaps one or more of the fields cpus_allowed, mems_allowed,
451 * or flags changed to new, trial values.
453 * Return 0 if valid, -errno if not.
456 static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
459 struct cpuset *c, *par;
461 /* Each of our child cpusets must be a subset of us */
462 list_for_each_entry(cont, &cur->css.cgroup->children, sibling) {
463 if (!is_cpuset_subset(cgroup_cs(cont), trial))
467 /* Remaining checks don't apply to root cpuset */
468 if (cur == &top_cpuset)
473 /* We must be a subset of our parent cpuset */
474 if (!is_cpuset_subset(trial, par))
478 * If either I or some sibling (!= me) is exclusive, we can't
481 list_for_each_entry(cont, &par->css.cgroup->children, sibling) {
483 if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
485 cpus_intersects(trial->cpus_allowed, c->cpus_allowed))
487 if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
489 nodes_intersects(trial->mems_allowed, c->mems_allowed))
493 /* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */
494 if (cgroup_task_count(cur->css.cgroup)) {
495 if (cpus_empty(trial->cpus_allowed) ||
496 nodes_empty(trial->mems_allowed)) {
505 * Helper routine for generate_sched_domains().
506 * Do cpusets a, b have overlapping cpus_allowed masks?
508 static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
510 return cpus_intersects(a->cpus_allowed, b->cpus_allowed);
514 update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
516 if (dattr->relax_domain_level < c->relax_domain_level)
517 dattr->relax_domain_level = c->relax_domain_level;
522 update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c)
526 list_add(&c->stack_list, &q);
527 while (!list_empty(&q)) {
530 struct cpuset *child;
532 cp = list_first_entry(&q, struct cpuset, stack_list);
535 if (cpus_empty(cp->cpus_allowed))
538 if (is_sched_load_balance(cp))
539 update_domain_attr(dattr, cp);
541 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
542 child = cgroup_cs(cont);
543 list_add_tail(&child->stack_list, &q);
549 * generate_sched_domains()
551 * This function builds a partial partition of the systems CPUs
552 * A 'partial partition' is a set of non-overlapping subsets whose
553 * union is a subset of that set.
554 * The output of this function needs to be passed to kernel/sched.c
555 * partition_sched_domains() routine, which will rebuild the scheduler's
556 * load balancing domains (sched domains) as specified by that partial
559 * See "What is sched_load_balance" in Documentation/cpusets.txt
560 * for a background explanation of this.
562 * Does not return errors, on the theory that the callers of this
563 * routine would rather not worry about failures to rebuild sched
564 * domains when operating in the severe memory shortage situations
565 * that could cause allocation failures below.
567 * Must be called with cgroup_lock held.
569 * The three key local variables below are:
570 * q - a linked-list queue of cpuset pointers, used to implement a
571 * top-down scan of all cpusets. This scan loads a pointer
572 * to each cpuset marked is_sched_load_balance into the
573 * array 'csa'. For our purposes, rebuilding the schedulers
574 * sched domains, we can ignore !is_sched_load_balance cpusets.
575 * csa - (for CpuSet Array) Array of pointers to all the cpusets
576 * that need to be load balanced, for convenient iterative
577 * access by the subsequent code that finds the best partition,
578 * i.e the set of domains (subsets) of CPUs such that the
579 * cpus_allowed of every cpuset marked is_sched_load_balance
580 * is a subset of one of these domains, while there are as
581 * many such domains as possible, each as small as possible.
582 * doms - Conversion of 'csa' to an array of cpumasks, for passing to
583 * the kernel/sched.c routine partition_sched_domains() in a
584 * convenient format, that can be easily compared to the prior
585 * value to determine what partition elements (sched domains)
586 * were changed (added or removed.)
588 * Finding the best partition (set of domains):
589 * The triple nested loops below over i, j, k scan over the
590 * load balanced cpusets (using the array of cpuset pointers in
591 * csa[]) looking for pairs of cpusets that have overlapping
592 * cpus_allowed, but which don't have the same 'pn' partition
593 * number and gives them in the same partition number. It keeps
594 * looping on the 'restart' label until it can no longer find
597 * The union of the cpus_allowed masks from the set of
598 * all cpusets having the same 'pn' value then form the one
599 * element of the partition (one sched domain) to be passed to
600 * partition_sched_domains().
602 static int generate_sched_domains(cpumask_t **domains,
603 struct sched_domain_attr **attributes)
605 LIST_HEAD(q); /* queue of cpusets to be scanned */
606 struct cpuset *cp; /* scans q */
607 struct cpuset **csa; /* array of all cpuset ptrs */
608 int csn; /* how many cpuset ptrs in csa so far */
609 int i, j, k; /* indices for partition finding loops */
610 cpumask_t *doms; /* resulting partition; i.e. sched domains */
611 struct sched_domain_attr *dattr; /* attributes for custom domains */
612 int ndoms = 0; /* number of sched domains in result */
613 int nslot; /* next empty doms[] cpumask_t slot */
619 /* Special case for the 99% of systems with one, full, sched domain */
620 if (is_sched_load_balance(&top_cpuset)) {
621 doms = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
625 dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
627 *dattr = SD_ATTR_INIT;
628 update_domain_attr_tree(dattr, &top_cpuset);
630 *doms = top_cpuset.cpus_allowed;
636 csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
641 list_add(&top_cpuset.stack_list, &q);
642 while (!list_empty(&q)) {
644 struct cpuset *child; /* scans child cpusets of cp */
646 cp = list_first_entry(&q, struct cpuset, stack_list);
649 if (cpus_empty(cp->cpus_allowed))
653 * All child cpusets contain a subset of the parent's cpus, so
654 * just skip them, and then we call update_domain_attr_tree()
655 * to calc relax_domain_level of the corresponding sched
658 if (is_sched_load_balance(cp)) {
663 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
664 child = cgroup_cs(cont);
665 list_add_tail(&child->stack_list, &q);
669 for (i = 0; i < csn; i++)
674 /* Find the best partition (set of sched domains) */
675 for (i = 0; i < csn; i++) {
676 struct cpuset *a = csa[i];
679 for (j = 0; j < csn; j++) {
680 struct cpuset *b = csa[j];
683 if (apn != bpn && cpusets_overlap(a, b)) {
684 for (k = 0; k < csn; k++) {
685 struct cpuset *c = csa[k];
690 ndoms--; /* one less element */
697 * Now we know how many domains to create.
698 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
700 doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL);
705 * The rest of the code, including the scheduler, can deal with
706 * dattr==NULL case. No need to abort if alloc fails.
708 dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
710 for (nslot = 0, i = 0; i < csn; i++) {
711 struct cpuset *a = csa[i];
716 /* Skip completed partitions */
722 if (nslot == ndoms) {
723 static int warnings = 10;
726 "rebuild_sched_domains confused:"
727 " nslot %d, ndoms %d, csn %d, i %d,"
729 nslot, ndoms, csn, i, apn);
737 *(dattr + nslot) = SD_ATTR_INIT;
738 for (j = i; j < csn; j++) {
739 struct cpuset *b = csa[j];
742 cpus_or(*dp, *dp, b->cpus_allowed);
744 update_domain_attr_tree(dattr + nslot, b);
746 /* Done with this partition */
752 BUG_ON(nslot != ndoms);
758 * Fallback to the default domain if kmalloc() failed.
759 * See comments in partition_sched_domains().
770 * Rebuild scheduler domains.
772 * Call with neither cgroup_mutex held nor within get_online_cpus().
773 * Takes both cgroup_mutex and get_online_cpus().
775 * Cannot be directly called from cpuset code handling changes
776 * to the cpuset pseudo-filesystem, because it cannot be called
777 * from code that already holds cgroup_mutex.
779 static void do_rebuild_sched_domains(struct work_struct *unused)
781 struct sched_domain_attr *attr;
787 /* Generate domain masks and attrs */
789 ndoms = generate_sched_domains(&doms, &attr);
792 /* Have scheduler rebuild the domains */
793 partition_sched_domains(ndoms, doms, attr);
798 static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);
801 * Rebuild scheduler domains, asynchronously via workqueue.
803 * If the flag 'sched_load_balance' of any cpuset with non-empty
804 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
805 * which has that flag enabled, or if any cpuset with a non-empty
806 * 'cpus' is removed, then call this routine to rebuild the
807 * scheduler's dynamic sched domains.
809 * The rebuild_sched_domains() and partition_sched_domains()
810 * routines must nest cgroup_lock() inside get_online_cpus(),
811 * but such cpuset changes as these must nest that locking the
812 * other way, holding cgroup_lock() for much of the code.
814 * So in order to avoid an ABBA deadlock, the cpuset code handling
815 * these user changes delegates the actual sched domain rebuilding
816 * to a separate workqueue thread, which ends up processing the
817 * above do_rebuild_sched_domains() function.
819 static void async_rebuild_sched_domains(void)
821 schedule_work(&rebuild_sched_domains_work);
825 * Accomplishes the same scheduler domain rebuild as the above
826 * async_rebuild_sched_domains(), however it directly calls the
827 * rebuild routine synchronously rather than calling it via an
828 * asynchronous work thread.
830 * This can only be called from code that is not holding
831 * cgroup_mutex (not nested in a cgroup_lock() call.)
833 void rebuild_sched_domains(void)
835 do_rebuild_sched_domains(NULL);
839 * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's
841 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
843 * Call with cgroup_mutex held. May take callback_mutex during call.
844 * Called for each task in a cgroup by cgroup_scan_tasks().
845 * Return nonzero if this tasks's cpus_allowed mask should be changed (in other
846 * words, if its mask is not equal to its cpuset's mask).
848 static int cpuset_test_cpumask(struct task_struct *tsk,
849 struct cgroup_scanner *scan)
851 return !cpus_equal(tsk->cpus_allowed,
852 (cgroup_cs(scan->cg))->cpus_allowed);
856 * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
858 * @scan: struct cgroup_scanner containing the cgroup of the task
860 * Called by cgroup_scan_tasks() for each task in a cgroup whose
861 * cpus_allowed mask needs to be changed.
863 * We don't need to re-check for the cgroup/cpuset membership, since we're
864 * holding cgroup_lock() at this point.
866 static void cpuset_change_cpumask(struct task_struct *tsk,
867 struct cgroup_scanner *scan)
869 set_cpus_allowed_ptr(tsk, &((cgroup_cs(scan->cg))->cpus_allowed));
873 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
874 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
875 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
877 * Called with cgroup_mutex held
879 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
880 * calling callback functions for each.
882 * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
885 static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
887 struct cgroup_scanner scan;
889 scan.cg = cs->css.cgroup;
890 scan.test_task = cpuset_test_cpumask;
891 scan.process_task = cpuset_change_cpumask;
893 cgroup_scan_tasks(&scan);
897 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
898 * @cs: the cpuset to consider
899 * @buf: buffer of cpu numbers written to this cpuset
901 static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
904 struct ptr_heap heap;
906 int is_load_balanced;
908 /* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */
909 if (cs == &top_cpuset)
913 * An empty cpus_allowed is ok only if the cpuset has no tasks.
914 * Since cpulist_parse() fails on an empty mask, we special case
915 * that parsing. The validate_change() call ensures that cpusets
916 * with tasks have cpus.
919 cpus_clear(trialcs->cpus_allowed);
921 retval = cpulist_parse(buf, &trialcs->cpus_allowed);
925 if (!cpus_subset(trialcs->cpus_allowed, cpu_online_map))
928 retval = validate_change(cs, trialcs);
932 /* Nothing to do if the cpus didn't change */
933 if (cpus_equal(cs->cpus_allowed, trialcs->cpus_allowed))
936 retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
940 is_load_balanced = is_sched_load_balance(trialcs);
942 mutex_lock(&callback_mutex);
943 cs->cpus_allowed = trialcs->cpus_allowed;
944 mutex_unlock(&callback_mutex);
947 * Scan tasks in the cpuset, and update the cpumasks of any
948 * that need an update.
950 update_tasks_cpumask(cs, &heap);
954 if (is_load_balanced)
955 async_rebuild_sched_domains();
962 * Migrate memory region from one set of nodes to another.
964 * Temporarilly set tasks mems_allowed to target nodes of migration,
965 * so that the migration code can allocate pages on these nodes.
967 * Call holding cgroup_mutex, so current's cpuset won't change
968 * during this call, as manage_mutex holds off any cpuset_attach()
969 * calls. Therefore we don't need to take task_lock around the
970 * call to guarantee_online_mems(), as we know no one is changing
973 * Hold callback_mutex around the two modifications of our tasks
974 * mems_allowed to synchronize with cpuset_mems_allowed().
976 * While the mm_struct we are migrating is typically from some
977 * other task, the task_struct mems_allowed that we are hacking
978 * is for our current task, which must allocate new pages for that
979 * migrating memory region.
981 * We call cpuset_update_task_memory_state() before hacking
982 * our tasks mems_allowed, so that we are assured of being in
983 * sync with our tasks cpuset, and in particular, callbacks to
984 * cpuset_update_task_memory_state() from nested page allocations
985 * won't see any mismatch of our cpuset and task mems_generation
986 * values, so won't overwrite our hacked tasks mems_allowed
990 static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
991 const nodemask_t *to)
993 struct task_struct *tsk = current;
995 cpuset_update_task_memory_state();
997 mutex_lock(&callback_mutex);
998 tsk->mems_allowed = *to;
999 mutex_unlock(&callback_mutex);
1001 do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
1003 mutex_lock(&callback_mutex);
1004 guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
1005 mutex_unlock(&callback_mutex);
1008 static void *cpuset_being_rebound;
1011 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
1012 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
1013 * @oldmem: old mems_allowed of cpuset cs
1015 * Called with cgroup_mutex held
1016 * Return 0 if successful, -errno if not.
1018 static int update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem)
1020 struct task_struct *p;
1021 struct mm_struct **mmarray;
1025 struct cgroup_iter it;
1028 cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
1030 fudge = 10; /* spare mmarray[] slots */
1031 fudge += cpus_weight(cs->cpus_allowed); /* imagine one fork-bomb/cpu */
1035 * Allocate mmarray[] to hold mm reference for each task
1036 * in cpuset cs. Can't kmalloc GFP_KERNEL while holding
1037 * tasklist_lock. We could use GFP_ATOMIC, but with a
1038 * few more lines of code, we can retry until we get a big
1039 * enough mmarray[] w/o using GFP_ATOMIC.
1042 ntasks = cgroup_task_count(cs->css.cgroup); /* guess */
1044 mmarray = kmalloc(ntasks * sizeof(*mmarray), GFP_KERNEL);
1047 read_lock(&tasklist_lock); /* block fork */
1048 if (cgroup_task_count(cs->css.cgroup) <= ntasks)
1049 break; /* got enough */
1050 read_unlock(&tasklist_lock); /* try again */
1056 /* Load up mmarray[] with mm reference for each task in cpuset. */
1057 cgroup_iter_start(cs->css.cgroup, &it);
1058 while ((p = cgroup_iter_next(cs->css.cgroup, &it))) {
1059 struct mm_struct *mm;
1063 "Cpuset mempolicy rebind incomplete.\n");
1066 mm = get_task_mm(p);
1071 cgroup_iter_end(cs->css.cgroup, &it);
1072 read_unlock(&tasklist_lock);
1075 * Now that we've dropped the tasklist spinlock, we can
1076 * rebind the vma mempolicies of each mm in mmarray[] to their
1077 * new cpuset, and release that mm. The mpol_rebind_mm()
1078 * call takes mmap_sem, which we couldn't take while holding
1079 * tasklist_lock. Forks can happen again now - the mpol_dup()
1080 * cpuset_being_rebound check will catch such forks, and rebind
1081 * their vma mempolicies too. Because we still hold the global
1082 * cgroup_mutex, we know that no other rebind effort will
1083 * be contending for the global variable cpuset_being_rebound.
1084 * It's ok if we rebind the same mm twice; mpol_rebind_mm()
1085 * is idempotent. Also migrate pages in each mm to new nodes.
1087 migrate = is_memory_migrate(cs);
1088 for (i = 0; i < n; i++) {
1089 struct mm_struct *mm = mmarray[i];
1091 mpol_rebind_mm(mm, &cs->mems_allowed);
1093 cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
1097 /* We're done rebinding vmas to this cpuset's new mems_allowed. */
1099 cpuset_being_rebound = NULL;
1106 * Handle user request to change the 'mems' memory placement
1107 * of a cpuset. Needs to validate the request, update the
1108 * cpusets mems_allowed and mems_generation, and for each
1109 * task in the cpuset, rebind any vma mempolicies and if
1110 * the cpuset is marked 'memory_migrate', migrate the tasks
1111 * pages to the new memory.
1113 * Call with cgroup_mutex held. May take callback_mutex during call.
1114 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
1115 * lock each such tasks mm->mmap_sem, scan its vma's and rebind
1116 * their mempolicies to the cpusets new mems_allowed.
1118 static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
1125 * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
1128 if (cs == &top_cpuset)
1132 * An empty mems_allowed is ok iff there are no tasks in the cpuset.
1133 * Since nodelist_parse() fails on an empty mask, we special case
1134 * that parsing. The validate_change() call ensures that cpusets
1135 * with tasks have memory.
1138 nodes_clear(trialcs->mems_allowed);
1140 retval = nodelist_parse(buf, trialcs->mems_allowed);
1144 if (!nodes_subset(trialcs->mems_allowed,
1145 node_states[N_HIGH_MEMORY]))
1148 oldmem = cs->mems_allowed;
1149 if (nodes_equal(oldmem, trialcs->mems_allowed)) {
1150 retval = 0; /* Too easy - nothing to do */
1153 retval = validate_change(cs, trialcs);
1157 mutex_lock(&callback_mutex);
1158 cs->mems_allowed = trialcs->mems_allowed;
1159 cs->mems_generation = cpuset_mems_generation++;
1160 mutex_unlock(&callback_mutex);
1162 retval = update_tasks_nodemask(cs, &oldmem);
1167 int current_cpuset_is_being_rebound(void)
1169 return task_cs(current) == cpuset_being_rebound;
1172 static int update_relax_domain_level(struct cpuset *cs, s64 val)
1174 if (val < -1 || val >= SD_LV_MAX)
1177 if (val != cs->relax_domain_level) {
1178 cs->relax_domain_level = val;
1179 if (!cpus_empty(cs->cpus_allowed) && is_sched_load_balance(cs))
1180 async_rebuild_sched_domains();
1187 * update_flag - read a 0 or a 1 in a file and update associated flag
1188 * bit: the bit to update (see cpuset_flagbits_t)
1189 * cs: the cpuset to update
1190 * turning_on: whether the flag is being set or cleared
1192 * Call with cgroup_mutex held.
1195 static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
1198 struct cpuset *trialcs;
1200 int balance_flag_changed;
1202 trialcs = alloc_trial_cpuset(cs);
1207 set_bit(bit, &trialcs->flags);
1209 clear_bit(bit, &trialcs->flags);
1211 err = validate_change(cs, trialcs);
1215 balance_flag_changed = (is_sched_load_balance(cs) !=
1216 is_sched_load_balance(trialcs));
1218 mutex_lock(&callback_mutex);
1219 cs->flags = trialcs->flags;
1220 mutex_unlock(&callback_mutex);
1222 if (!cpus_empty(trialcs->cpus_allowed) && balance_flag_changed)
1223 async_rebuild_sched_domains();
1226 free_trial_cpuset(trialcs);
1231 * Frequency meter - How fast is some event occurring?
1233 * These routines manage a digitally filtered, constant time based,
1234 * event frequency meter. There are four routines:
1235 * fmeter_init() - initialize a frequency meter.
1236 * fmeter_markevent() - called each time the event happens.
1237 * fmeter_getrate() - returns the recent rate of such events.
1238 * fmeter_update() - internal routine used to update fmeter.
1240 * A common data structure is passed to each of these routines,
1241 * which is used to keep track of the state required to manage the
1242 * frequency meter and its digital filter.
1244 * The filter works on the number of events marked per unit time.
1245 * The filter is single-pole low-pass recursive (IIR). The time unit
1246 * is 1 second. Arithmetic is done using 32-bit integers scaled to
1247 * simulate 3 decimal digits of precision (multiplied by 1000).
1249 * With an FM_COEF of 933, and a time base of 1 second, the filter
1250 * has a half-life of 10 seconds, meaning that if the events quit
1251 * happening, then the rate returned from the fmeter_getrate()
1252 * will be cut in half each 10 seconds, until it converges to zero.
1254 * It is not worth doing a real infinitely recursive filter. If more
1255 * than FM_MAXTICKS ticks have elapsed since the last filter event,
1256 * just compute FM_MAXTICKS ticks worth, by which point the level
1259 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
1260 * arithmetic overflow in the fmeter_update() routine.
1262 * Given the simple 32 bit integer arithmetic used, this meter works
1263 * best for reporting rates between one per millisecond (msec) and
1264 * one per 32 (approx) seconds. At constant rates faster than one
1265 * per msec it maxes out at values just under 1,000,000. At constant
1266 * rates between one per msec, and one per second it will stabilize
1267 * to a value N*1000, where N is the rate of events per second.
1268 * At constant rates between one per second and one per 32 seconds,
1269 * it will be choppy, moving up on the seconds that have an event,
1270 * and then decaying until the next event. At rates slower than
1271 * about one in 32 seconds, it decays all the way back to zero between
1275 #define FM_COEF 933 /* coefficient for half-life of 10 secs */
1276 #define FM_MAXTICKS ((time_t)99) /* useless computing more ticks than this */
1277 #define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
1278 #define FM_SCALE 1000 /* faux fixed point scale */
1280 /* Initialize a frequency meter */
1281 static void fmeter_init(struct fmeter *fmp)
1286 spin_lock_init(&fmp->lock);
1289 /* Internal meter update - process cnt events and update value */
1290 static void fmeter_update(struct fmeter *fmp)
1292 time_t now = get_seconds();
1293 time_t ticks = now - fmp->time;
1298 ticks = min(FM_MAXTICKS, ticks);
1300 fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
1303 fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
1307 /* Process any previous ticks, then bump cnt by one (times scale). */
1308 static void fmeter_markevent(struct fmeter *fmp)
1310 spin_lock(&fmp->lock);
1312 fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
1313 spin_unlock(&fmp->lock);
1316 /* Process any previous ticks, then return current value. */
1317 static int fmeter_getrate(struct fmeter *fmp)
1321 spin_lock(&fmp->lock);
1324 spin_unlock(&fmp->lock);
1328 /* Protected by cgroup_lock */
1329 static cpumask_var_t cpus_attach;
1331 /* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
1332 static int cpuset_can_attach(struct cgroup_subsys *ss,
1333 struct cgroup *cont, struct task_struct *tsk)
1335 struct cpuset *cs = cgroup_cs(cont);
1338 if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
1341 if (tsk->flags & PF_THREAD_BOUND) {
1342 mutex_lock(&callback_mutex);
1343 if (!cpus_equal(tsk->cpus_allowed, cs->cpus_allowed))
1345 mutex_unlock(&callback_mutex);
1348 return ret < 0 ? ret : security_task_setscheduler(tsk, 0, NULL);
1351 static void cpuset_attach(struct cgroup_subsys *ss,
1352 struct cgroup *cont, struct cgroup *oldcont,
1353 struct task_struct *tsk)
1355 nodemask_t from, to;
1356 struct mm_struct *mm;
1357 struct cpuset *cs = cgroup_cs(cont);
1358 struct cpuset *oldcs = cgroup_cs(oldcont);
1361 if (cs == &top_cpuset) {
1362 cpumask_copy(cpus_attach, cpu_possible_mask);
1364 mutex_lock(&callback_mutex);
1365 guarantee_online_cpus(cs, cpus_attach);
1366 mutex_unlock(&callback_mutex);
1368 err = set_cpus_allowed_ptr(tsk, cpus_attach);
1372 from = oldcs->mems_allowed;
1373 to = cs->mems_allowed;
1374 mm = get_task_mm(tsk);
1376 mpol_rebind_mm(mm, &to);
1377 if (is_memory_migrate(cs))
1378 cpuset_migrate_mm(mm, &from, &to);
1383 /* The various types of files and directories in a cpuset file system */
1386 FILE_MEMORY_MIGRATE,
1392 FILE_SCHED_LOAD_BALANCE,
1393 FILE_SCHED_RELAX_DOMAIN_LEVEL,
1394 FILE_MEMORY_PRESSURE_ENABLED,
1395 FILE_MEMORY_PRESSURE,
1398 } cpuset_filetype_t;
1400 static int cpuset_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
1403 struct cpuset *cs = cgroup_cs(cgrp);
1404 cpuset_filetype_t type = cft->private;
1406 if (!cgroup_lock_live_group(cgrp))
1410 case FILE_CPU_EXCLUSIVE:
1411 retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
1413 case FILE_MEM_EXCLUSIVE:
1414 retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
1416 case FILE_MEM_HARDWALL:
1417 retval = update_flag(CS_MEM_HARDWALL, cs, val);
1419 case FILE_SCHED_LOAD_BALANCE:
1420 retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
1422 case FILE_MEMORY_MIGRATE:
1423 retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
1425 case FILE_MEMORY_PRESSURE_ENABLED:
1426 cpuset_memory_pressure_enabled = !!val;
1428 case FILE_MEMORY_PRESSURE:
1431 case FILE_SPREAD_PAGE:
1432 retval = update_flag(CS_SPREAD_PAGE, cs, val);
1433 cs->mems_generation = cpuset_mems_generation++;
1435 case FILE_SPREAD_SLAB:
1436 retval = update_flag(CS_SPREAD_SLAB, cs, val);
1437 cs->mems_generation = cpuset_mems_generation++;
1447 static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
1450 struct cpuset *cs = cgroup_cs(cgrp);
1451 cpuset_filetype_t type = cft->private;
1453 if (!cgroup_lock_live_group(cgrp))
1457 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1458 retval = update_relax_domain_level(cs, val);
1469 * Common handling for a write to a "cpus" or "mems" file.
1471 static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
1475 struct cpuset *cs = cgroup_cs(cgrp);
1476 struct cpuset *trialcs;
1478 if (!cgroup_lock_live_group(cgrp))
1481 trialcs = alloc_trial_cpuset(cs);
1485 switch (cft->private) {
1487 retval = update_cpumask(cs, trialcs, buf);
1490 retval = update_nodemask(cs, trialcs, buf);
1497 free_trial_cpuset(trialcs);
1503 * These ascii lists should be read in a single call, by using a user
1504 * buffer large enough to hold the entire map. If read in smaller
1505 * chunks, there is no guarantee of atomicity. Since the display format
1506 * used, list of ranges of sequential numbers, is variable length,
1507 * and since these maps can change value dynamically, one could read
1508 * gibberish by doing partial reads while a list was changing.
1509 * A single large read to a buffer that crosses a page boundary is
1510 * ok, because the result being copied to user land is not recomputed
1511 * across a page fault.
1514 static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs)
1518 mutex_lock(&callback_mutex);
1519 ret = cpulist_scnprintf(page, PAGE_SIZE, &cs->cpus_allowed);
1520 mutex_unlock(&callback_mutex);
1525 static int cpuset_sprintf_memlist(char *page, struct cpuset *cs)
1529 mutex_lock(&callback_mutex);
1530 mask = cs->mems_allowed;
1531 mutex_unlock(&callback_mutex);
1533 return nodelist_scnprintf(page, PAGE_SIZE, mask);
1536 static ssize_t cpuset_common_file_read(struct cgroup *cont,
1540 size_t nbytes, loff_t *ppos)
1542 struct cpuset *cs = cgroup_cs(cont);
1543 cpuset_filetype_t type = cft->private;
1548 if (!(page = (char *)__get_free_page(GFP_TEMPORARY)))
1555 s += cpuset_sprintf_cpulist(s, cs);
1558 s += cpuset_sprintf_memlist(s, cs);
1566 retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page);
1568 free_page((unsigned long)page);
1572 static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft)
1574 struct cpuset *cs = cgroup_cs(cont);
1575 cpuset_filetype_t type = cft->private;
1577 case FILE_CPU_EXCLUSIVE:
1578 return is_cpu_exclusive(cs);
1579 case FILE_MEM_EXCLUSIVE:
1580 return is_mem_exclusive(cs);
1581 case FILE_MEM_HARDWALL:
1582 return is_mem_hardwall(cs);
1583 case FILE_SCHED_LOAD_BALANCE:
1584 return is_sched_load_balance(cs);
1585 case FILE_MEMORY_MIGRATE:
1586 return is_memory_migrate(cs);
1587 case FILE_MEMORY_PRESSURE_ENABLED:
1588 return cpuset_memory_pressure_enabled;
1589 case FILE_MEMORY_PRESSURE:
1590 return fmeter_getrate(&cs->fmeter);
1591 case FILE_SPREAD_PAGE:
1592 return is_spread_page(cs);
1593 case FILE_SPREAD_SLAB:
1594 return is_spread_slab(cs);
1599 /* Unreachable but makes gcc happy */
1603 static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)
1605 struct cpuset *cs = cgroup_cs(cont);
1606 cpuset_filetype_t type = cft->private;
1608 case FILE_SCHED_RELAX_DOMAIN_LEVEL:
1609 return cs->relax_domain_level;
1614 /* Unrechable but makes gcc happy */
1620 * for the common functions, 'private' gives the type of file
1623 static struct cftype files[] = {
1626 .read = cpuset_common_file_read,
1627 .write_string = cpuset_write_resmask,
1628 .max_write_len = (100U + 6 * NR_CPUS),
1629 .private = FILE_CPULIST,
1634 .read = cpuset_common_file_read,
1635 .write_string = cpuset_write_resmask,
1636 .max_write_len = (100U + 6 * MAX_NUMNODES),
1637 .private = FILE_MEMLIST,
1641 .name = "cpu_exclusive",
1642 .read_u64 = cpuset_read_u64,
1643 .write_u64 = cpuset_write_u64,
1644 .private = FILE_CPU_EXCLUSIVE,
1648 .name = "mem_exclusive",
1649 .read_u64 = cpuset_read_u64,
1650 .write_u64 = cpuset_write_u64,
1651 .private = FILE_MEM_EXCLUSIVE,
1655 .name = "mem_hardwall",
1656 .read_u64 = cpuset_read_u64,
1657 .write_u64 = cpuset_write_u64,
1658 .private = FILE_MEM_HARDWALL,
1662 .name = "sched_load_balance",
1663 .read_u64 = cpuset_read_u64,
1664 .write_u64 = cpuset_write_u64,
1665 .private = FILE_SCHED_LOAD_BALANCE,
1669 .name = "sched_relax_domain_level",
1670 .read_s64 = cpuset_read_s64,
1671 .write_s64 = cpuset_write_s64,
1672 .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
1676 .name = "memory_migrate",
1677 .read_u64 = cpuset_read_u64,
1678 .write_u64 = cpuset_write_u64,
1679 .private = FILE_MEMORY_MIGRATE,
1683 .name = "memory_pressure",
1684 .read_u64 = cpuset_read_u64,
1685 .write_u64 = cpuset_write_u64,
1686 .private = FILE_MEMORY_PRESSURE,
1690 .name = "memory_spread_page",
1691 .read_u64 = cpuset_read_u64,
1692 .write_u64 = cpuset_write_u64,
1693 .private = FILE_SPREAD_PAGE,
1697 .name = "memory_spread_slab",
1698 .read_u64 = cpuset_read_u64,
1699 .write_u64 = cpuset_write_u64,
1700 .private = FILE_SPREAD_SLAB,
1704 static struct cftype cft_memory_pressure_enabled = {
1705 .name = "memory_pressure_enabled",
1706 .read_u64 = cpuset_read_u64,
1707 .write_u64 = cpuset_write_u64,
1708 .private = FILE_MEMORY_PRESSURE_ENABLED,
1711 static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
1715 err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
1718 /* memory_pressure_enabled is in root cpuset only */
1720 err = cgroup_add_file(cont, ss,
1721 &cft_memory_pressure_enabled);
1726 * post_clone() is called at the end of cgroup_clone().
1727 * 'cgroup' was just created automatically as a result of
1728 * a cgroup_clone(), and the current task is about to
1729 * be moved into 'cgroup'.
1731 * Currently we refuse to set up the cgroup - thereby
1732 * refusing the task to be entered, and as a result refusing
1733 * the sys_unshare() or clone() which initiated it - if any
1734 * sibling cpusets have exclusive cpus or mem.
1736 * If this becomes a problem for some users who wish to
1737 * allow that scenario, then cpuset_post_clone() could be
1738 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
1739 * (and likewise for mems) to the new cgroup. Called with cgroup_mutex
1742 static void cpuset_post_clone(struct cgroup_subsys *ss,
1743 struct cgroup *cgroup)
1745 struct cgroup *parent, *child;
1746 struct cpuset *cs, *parent_cs;
1748 parent = cgroup->parent;
1749 list_for_each_entry(child, &parent->children, sibling) {
1750 cs = cgroup_cs(child);
1751 if (is_mem_exclusive(cs) || is_cpu_exclusive(cs))
1754 cs = cgroup_cs(cgroup);
1755 parent_cs = cgroup_cs(parent);
1757 cs->mems_allowed = parent_cs->mems_allowed;
1758 cs->cpus_allowed = parent_cs->cpus_allowed;
1763 * cpuset_create - create a cpuset
1764 * ss: cpuset cgroup subsystem
1765 * cont: control group that the new cpuset will be part of
1768 static struct cgroup_subsys_state *cpuset_create(
1769 struct cgroup_subsys *ss,
1770 struct cgroup *cont)
1773 struct cpuset *parent;
1775 if (!cont->parent) {
1776 /* This is early initialization for the top cgroup */
1777 top_cpuset.mems_generation = cpuset_mems_generation++;
1778 return &top_cpuset.css;
1780 parent = cgroup_cs(cont->parent);
1781 cs = kmalloc(sizeof(*cs), GFP_KERNEL);
1783 return ERR_PTR(-ENOMEM);
1785 cpuset_update_task_memory_state();
1787 if (is_spread_page(parent))
1788 set_bit(CS_SPREAD_PAGE, &cs->flags);
1789 if (is_spread_slab(parent))
1790 set_bit(CS_SPREAD_SLAB, &cs->flags);
1791 set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
1792 cpus_clear(cs->cpus_allowed);
1793 nodes_clear(cs->mems_allowed);
1794 cs->mems_generation = cpuset_mems_generation++;
1795 fmeter_init(&cs->fmeter);
1796 cs->relax_domain_level = -1;
1798 cs->parent = parent;
1799 number_of_cpusets++;
1804 * If the cpuset being removed has its flag 'sched_load_balance'
1805 * enabled, then simulate turning sched_load_balance off, which
1806 * will call async_rebuild_sched_domains().
1809 static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
1811 struct cpuset *cs = cgroup_cs(cont);
1813 cpuset_update_task_memory_state();
1815 if (is_sched_load_balance(cs))
1816 update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
1818 number_of_cpusets--;
1822 struct cgroup_subsys cpuset_subsys = {
1824 .create = cpuset_create,
1825 .destroy = cpuset_destroy,
1826 .can_attach = cpuset_can_attach,
1827 .attach = cpuset_attach,
1828 .populate = cpuset_populate,
1829 .post_clone = cpuset_post_clone,
1830 .subsys_id = cpuset_subsys_id,
1835 * cpuset_init_early - just enough so that the calls to
1836 * cpuset_update_task_memory_state() in early init code
1840 int __init cpuset_init_early(void)
1842 top_cpuset.mems_generation = cpuset_mems_generation++;
1848 * cpuset_init - initialize cpusets at system boot
1850 * Description: Initialize top_cpuset and the cpuset internal file system,
1853 int __init cpuset_init(void)
1857 cpus_setall(top_cpuset.cpus_allowed);
1858 nodes_setall(top_cpuset.mems_allowed);
1860 fmeter_init(&top_cpuset.fmeter);
1861 top_cpuset.mems_generation = cpuset_mems_generation++;
1862 set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
1863 top_cpuset.relax_domain_level = -1;
1865 err = register_filesystem(&cpuset_fs_type);
1869 if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
1872 number_of_cpusets = 1;
1877 * cpuset_do_move_task - move a given task to another cpuset
1878 * @tsk: pointer to task_struct the task to move
1879 * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner
1881 * Called by cgroup_scan_tasks() for each task in a cgroup.
1882 * Return nonzero to stop the walk through the tasks.
1884 static void cpuset_do_move_task(struct task_struct *tsk,
1885 struct cgroup_scanner *scan)
1887 struct cpuset_hotplug_scanner *chsp;
1889 chsp = container_of(scan, struct cpuset_hotplug_scanner, scan);
1890 cgroup_attach_task(chsp->to, tsk);
1894 * move_member_tasks_to_cpuset - move tasks from one cpuset to another
1895 * @from: cpuset in which the tasks currently reside
1896 * @to: cpuset to which the tasks will be moved
1898 * Called with cgroup_mutex held
1899 * callback_mutex must not be held, as cpuset_attach() will take it.
1901 * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
1902 * calling callback functions for each.
1904 static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to)
1906 struct cpuset_hotplug_scanner scan;
1908 scan.scan.cg = from->css.cgroup;
1909 scan.scan.test_task = NULL; /* select all tasks in cgroup */
1910 scan.scan.process_task = cpuset_do_move_task;
1911 scan.scan.heap = NULL;
1912 scan.to = to->css.cgroup;
1914 if (cgroup_scan_tasks(&scan.scan))
1915 printk(KERN_ERR "move_member_tasks_to_cpuset: "
1916 "cgroup_scan_tasks failed\n");
1920 * If CPU and/or memory hotplug handlers, below, unplug any CPUs
1921 * or memory nodes, we need to walk over the cpuset hierarchy,
1922 * removing that CPU or node from all cpusets. If this removes the
1923 * last CPU or node from a cpuset, then move the tasks in the empty
1924 * cpuset to its next-highest non-empty parent.
1926 * Called with cgroup_mutex held
1927 * callback_mutex must not be held, as cpuset_attach() will take it.
1929 static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
1931 struct cpuset *parent;
1934 * The cgroup's css_sets list is in use if there are tasks
1935 * in the cpuset; the list is empty if there are none;
1936 * the cs->css.refcnt seems always 0.
1938 if (list_empty(&cs->css.cgroup->css_sets))
1942 * Find its next-highest non-empty parent, (top cpuset
1943 * has online cpus, so can't be empty).
1945 parent = cs->parent;
1946 while (cpus_empty(parent->cpus_allowed) ||
1947 nodes_empty(parent->mems_allowed))
1948 parent = parent->parent;
1950 move_member_tasks_to_cpuset(cs, parent);
1954 * Walk the specified cpuset subtree and look for empty cpusets.
1955 * The tasks of such cpuset must be moved to a parent cpuset.
1957 * Called with cgroup_mutex held. We take callback_mutex to modify
1958 * cpus_allowed and mems_allowed.
1960 * This walk processes the tree from top to bottom, completing one layer
1961 * before dropping down to the next. It always processes a node before
1962 * any of its children.
1964 * For now, since we lack memory hot unplug, we'll never see a cpuset
1965 * that has tasks along with an empty 'mems'. But if we did see such
1966 * a cpuset, we'd handle it just like we do if its 'cpus' was empty.
1968 static void scan_for_empty_cpusets(struct cpuset *root)
1971 struct cpuset *cp; /* scans cpusets being updated */
1972 struct cpuset *child; /* scans child cpusets of cp */
1973 struct cgroup *cont;
1976 list_add_tail((struct list_head *)&root->stack_list, &queue);
1978 while (!list_empty(&queue)) {
1979 cp = list_first_entry(&queue, struct cpuset, stack_list);
1980 list_del(queue.next);
1981 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
1982 child = cgroup_cs(cont);
1983 list_add_tail(&child->stack_list, &queue);
1986 /* Continue past cpusets with all cpus, mems online */
1987 if (cpus_subset(cp->cpus_allowed, cpu_online_map) &&
1988 nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
1991 oldmems = cp->mems_allowed;
1993 /* Remove offline cpus and mems from this cpuset. */
1994 mutex_lock(&callback_mutex);
1995 cpus_and(cp->cpus_allowed, cp->cpus_allowed, cpu_online_map);
1996 nodes_and(cp->mems_allowed, cp->mems_allowed,
1997 node_states[N_HIGH_MEMORY]);
1998 mutex_unlock(&callback_mutex);
2000 /* Move tasks from the empty cpuset to a parent */
2001 if (cpus_empty(cp->cpus_allowed) ||
2002 nodes_empty(cp->mems_allowed))
2003 remove_tasks_in_empty_cpuset(cp);
2005 update_tasks_cpumask(cp, NULL);
2006 update_tasks_nodemask(cp, &oldmems);
2012 * The top_cpuset tracks what CPUs and Memory Nodes are online,
2013 * period. This is necessary in order to make cpusets transparent
2014 * (of no affect) on systems that are actively using CPU hotplug
2015 * but making no active use of cpusets.
2017 * This routine ensures that top_cpuset.cpus_allowed tracks
2018 * cpu_online_map on each CPU hotplug (cpuhp) event.
2020 * Called within get_online_cpus(). Needs to call cgroup_lock()
2021 * before calling generate_sched_domains().
2023 static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
2024 unsigned long phase, void *unused_cpu)
2026 struct sched_domain_attr *attr;
2032 case CPU_ONLINE_FROZEN:
2034 case CPU_DEAD_FROZEN:
2042 top_cpuset.cpus_allowed = cpu_online_map;
2043 scan_for_empty_cpusets(&top_cpuset);
2044 ndoms = generate_sched_domains(&doms, &attr);
2047 /* Have scheduler rebuild the domains */
2048 partition_sched_domains(ndoms, doms, attr);
2053 #ifdef CONFIG_MEMORY_HOTPLUG
2055 * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
2056 * Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
2057 * See also the previous routine cpuset_track_online_cpus().
2059 static int cpuset_track_online_nodes(struct notifier_block *self,
2060 unsigned long action, void *arg)
2065 top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2068 top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2069 scan_for_empty_cpusets(&top_cpuset);
2080 * cpuset_init_smp - initialize cpus_allowed
2082 * Description: Finish top cpuset after cpu, node maps are initialized
2085 void __init cpuset_init_smp(void)
2087 top_cpuset.cpus_allowed = cpu_online_map;
2088 top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
2090 hotcpu_notifier(cpuset_track_online_cpus, 0);
2091 hotplug_memory_notifier(cpuset_track_online_nodes, 10);
2095 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
2096 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
2097 * @pmask: pointer to cpumask_t variable to receive cpus_allowed set.
2099 * Description: Returns the cpumask_t cpus_allowed of the cpuset
2100 * attached to the specified @tsk. Guaranteed to return some non-empty
2101 * subset of cpu_online_map, even if this means going outside the
2105 void cpuset_cpus_allowed(struct task_struct *tsk, cpumask_t *pmask)
2107 mutex_lock(&callback_mutex);
2108 cpuset_cpus_allowed_locked(tsk, pmask);
2109 mutex_unlock(&callback_mutex);
2113 * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset.
2114 * Must be called with callback_mutex held.
2116 void cpuset_cpus_allowed_locked(struct task_struct *tsk, cpumask_t *pmask)
2119 guarantee_online_cpus(task_cs(tsk), pmask);
2123 void cpuset_init_current_mems_allowed(void)
2125 nodes_setall(current->mems_allowed);
2129 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
2130 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
2132 * Description: Returns the nodemask_t mems_allowed of the cpuset
2133 * attached to the specified @tsk. Guaranteed to return some non-empty
2134 * subset of node_states[N_HIGH_MEMORY], even if this means going outside the
2138 nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
2142 mutex_lock(&callback_mutex);
2144 guarantee_online_mems(task_cs(tsk), &mask);
2146 mutex_unlock(&callback_mutex);
2152 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
2153 * @nodemask: the nodemask to be checked
2155 * Are any of the nodes in the nodemask allowed in current->mems_allowed?
2157 int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
2159 return nodes_intersects(*nodemask, current->mems_allowed);
2163 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
2164 * mem_hardwall ancestor to the specified cpuset. Call holding
2165 * callback_mutex. If no ancestor is mem_exclusive or mem_hardwall
2166 * (an unusual configuration), then returns the root cpuset.
2168 static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
2170 while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent)
2176 * cpuset_zone_allowed_softwall - Can we allocate on zone z's memory node?
2177 * @z: is this zone on an allowed node?
2178 * @gfp_mask: memory allocation flags
2180 * If we're in interrupt, yes, we can always allocate. If
2181 * __GFP_THISNODE is set, yes, we can always allocate. If zone
2182 * z's node is in our tasks mems_allowed, yes. If it's not a
2183 * __GFP_HARDWALL request and this zone's nodes is in the nearest
2184 * hardwalled cpuset ancestor to this tasks cpuset, yes.
2185 * If the task has been OOM killed and has access to memory reserves
2186 * as specified by the TIF_MEMDIE flag, yes.
2189 * If __GFP_HARDWALL is set, cpuset_zone_allowed_softwall()
2190 * reduces to cpuset_zone_allowed_hardwall(). Otherwise,
2191 * cpuset_zone_allowed_softwall() might sleep, and might allow a zone
2192 * from an enclosing cpuset.
2194 * cpuset_zone_allowed_hardwall() only handles the simpler case of
2195 * hardwall cpusets, and never sleeps.
2197 * The __GFP_THISNODE placement logic is really handled elsewhere,
2198 * by forcibly using a zonelist starting at a specified node, and by
2199 * (in get_page_from_freelist()) refusing to consider the zones for
2200 * any node on the zonelist except the first. By the time any such
2201 * calls get to this routine, we should just shut up and say 'yes'.
2203 * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
2204 * and do not allow allocations outside the current tasks cpuset
2205 * unless the task has been OOM killed as is marked TIF_MEMDIE.
2206 * GFP_KERNEL allocations are not so marked, so can escape to the
2207 * nearest enclosing hardwalled ancestor cpuset.
2209 * Scanning up parent cpusets requires callback_mutex. The
2210 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
2211 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
2212 * current tasks mems_allowed came up empty on the first pass over
2213 * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
2214 * cpuset are short of memory, might require taking the callback_mutex
2217 * The first call here from mm/page_alloc:get_page_from_freelist()
2218 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
2219 * so no allocation on a node outside the cpuset is allowed (unless
2220 * in interrupt, of course).
2222 * The second pass through get_page_from_freelist() doesn't even call
2223 * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
2224 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
2225 * in alloc_flags. That logic and the checks below have the combined
2227 * in_interrupt - any node ok (current task context irrelevant)
2228 * GFP_ATOMIC - any node ok
2229 * TIF_MEMDIE - any node ok
2230 * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
2231 * GFP_USER - only nodes in current tasks mems allowed ok.
2234 * Don't call cpuset_zone_allowed_softwall if you can't sleep, unless you
2235 * pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
2236 * the code that might scan up ancestor cpusets and sleep.
2239 int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
2241 int node; /* node that zone z is on */
2242 const struct cpuset *cs; /* current cpuset ancestors */
2243 int allowed; /* is allocation in zone z allowed? */
2245 if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2247 node = zone_to_nid(z);
2248 might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
2249 if (node_isset(node, current->mems_allowed))
2252 * Allow tasks that have access to memory reserves because they have
2253 * been OOM killed to get memory anywhere.
2255 if (unlikely(test_thread_flag(TIF_MEMDIE)))
2257 if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
2260 if (current->flags & PF_EXITING) /* Let dying task have memory */
2263 /* Not hardwall and node outside mems_allowed: scan up cpusets */
2264 mutex_lock(&callback_mutex);
2267 cs = nearest_hardwall_ancestor(task_cs(current));
2268 task_unlock(current);
2270 allowed = node_isset(node, cs->mems_allowed);
2271 mutex_unlock(&callback_mutex);
2276 * cpuset_zone_allowed_hardwall - Can we allocate on zone z's memory node?
2277 * @z: is this zone on an allowed node?
2278 * @gfp_mask: memory allocation flags
2280 * If we're in interrupt, yes, we can always allocate.
2281 * If __GFP_THISNODE is set, yes, we can always allocate. If zone
2282 * z's node is in our tasks mems_allowed, yes. If the task has been
2283 * OOM killed and has access to memory reserves as specified by the
2284 * TIF_MEMDIE flag, yes. Otherwise, no.
2286 * The __GFP_THISNODE placement logic is really handled elsewhere,
2287 * by forcibly using a zonelist starting at a specified node, and by
2288 * (in get_page_from_freelist()) refusing to consider the zones for
2289 * any node on the zonelist except the first. By the time any such
2290 * calls get to this routine, we should just shut up and say 'yes'.
2292 * Unlike the cpuset_zone_allowed_softwall() variant, above,
2293 * this variant requires that the zone be in the current tasks
2294 * mems_allowed or that we're in interrupt. It does not scan up the
2295 * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
2299 int __cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask)
2301 int node; /* node that zone z is on */
2303 if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
2305 node = zone_to_nid(z);
2306 if (node_isset(node, current->mems_allowed))
2309 * Allow tasks that have access to memory reserves because they have
2310 * been OOM killed to get memory anywhere.
2312 if (unlikely(test_thread_flag(TIF_MEMDIE)))
2318 * cpuset_lock - lock out any changes to cpuset structures
2320 * The out of memory (oom) code needs to mutex_lock cpusets
2321 * from being changed while it scans the tasklist looking for a
2322 * task in an overlapping cpuset. Expose callback_mutex via this
2323 * cpuset_lock() routine, so the oom code can lock it, before
2324 * locking the task list. The tasklist_lock is a spinlock, so
2325 * must be taken inside callback_mutex.
2328 void cpuset_lock(void)
2330 mutex_lock(&callback_mutex);
2334 * cpuset_unlock - release lock on cpuset changes
2336 * Undo the lock taken in a previous cpuset_lock() call.
2339 void cpuset_unlock(void)
2341 mutex_unlock(&callback_mutex);
2345 * cpuset_mem_spread_node() - On which node to begin search for a page
2347 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
2348 * tasks in a cpuset with is_spread_page or is_spread_slab set),
2349 * and if the memory allocation used cpuset_mem_spread_node()
2350 * to determine on which node to start looking, as it will for
2351 * certain page cache or slab cache pages such as used for file
2352 * system buffers and inode caches, then instead of starting on the
2353 * local node to look for a free page, rather spread the starting
2354 * node around the tasks mems_allowed nodes.
2356 * We don't have to worry about the returned node being offline
2357 * because "it can't happen", and even if it did, it would be ok.
2359 * The routines calling guarantee_online_mems() are careful to
2360 * only set nodes in task->mems_allowed that are online. So it
2361 * should not be possible for the following code to return an
2362 * offline node. But if it did, that would be ok, as this routine
2363 * is not returning the node where the allocation must be, only
2364 * the node where the search should start. The zonelist passed to
2365 * __alloc_pages() will include all nodes. If the slab allocator
2366 * is passed an offline node, it will fall back to the local node.
2367 * See kmem_cache_alloc_node().
2370 int cpuset_mem_spread_node(void)
2374 node = next_node(current->cpuset_mem_spread_rotor, current->mems_allowed);
2375 if (node == MAX_NUMNODES)
2376 node = first_node(current->mems_allowed);
2377 current->cpuset_mem_spread_rotor = node;
2380 EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
2383 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
2384 * @tsk1: pointer to task_struct of some task.
2385 * @tsk2: pointer to task_struct of some other task.
2387 * Description: Return true if @tsk1's mems_allowed intersects the
2388 * mems_allowed of @tsk2. Used by the OOM killer to determine if
2389 * one of the task's memory usage might impact the memory available
2393 int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
2394 const struct task_struct *tsk2)
2396 return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
2400 * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
2401 * @task: pointer to task_struct of some task.
2403 * Description: Prints @task's name, cpuset name, and cached copy of its
2404 * mems_allowed to the kernel log. Must hold task_lock(task) to allow
2405 * dereferencing task_cs(task).
2407 void cpuset_print_task_mems_allowed(struct task_struct *tsk)
2409 struct dentry *dentry;
2411 dentry = task_cs(tsk)->css.cgroup->dentry;
2412 spin_lock(&cpuset_buffer_lock);
2413 snprintf(cpuset_name, CPUSET_NAME_LEN,
2414 dentry ? (const char *)dentry->d_name.name : "/");
2415 nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
2417 printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
2418 tsk->comm, cpuset_name, cpuset_nodelist);
2419 spin_unlock(&cpuset_buffer_lock);
2423 * Collection of memory_pressure is suppressed unless
2424 * this flag is enabled by writing "1" to the special
2425 * cpuset file 'memory_pressure_enabled' in the root cpuset.
2428 int cpuset_memory_pressure_enabled __read_mostly;
2431 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
2433 * Keep a running average of the rate of synchronous (direct)
2434 * page reclaim efforts initiated by tasks in each cpuset.
2436 * This represents the rate at which some task in the cpuset
2437 * ran low on memory on all nodes it was allowed to use, and
2438 * had to enter the kernels page reclaim code in an effort to
2439 * create more free memory by tossing clean pages or swapping
2440 * or writing dirty pages.
2442 * Display to user space in the per-cpuset read-only file
2443 * "memory_pressure". Value displayed is an integer
2444 * representing the recent rate of entry into the synchronous
2445 * (direct) page reclaim by any task attached to the cpuset.
2448 void __cpuset_memory_pressure_bump(void)
2451 fmeter_markevent(&task_cs(current)->fmeter);
2452 task_unlock(current);
2455 #ifdef CONFIG_PROC_PID_CPUSET
2457 * proc_cpuset_show()
2458 * - Print tasks cpuset path into seq_file.
2459 * - Used for /proc/<pid>/cpuset.
2460 * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
2461 * doesn't really matter if tsk->cpuset changes after we read it,
2462 * and we take cgroup_mutex, keeping cpuset_attach() from changing it
2465 static int proc_cpuset_show(struct seq_file *m, void *unused_v)
2468 struct task_struct *tsk;
2470 struct cgroup_subsys_state *css;
2474 buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
2480 tsk = get_pid_task(pid, PIDTYPE_PID);
2486 css = task_subsys_state(tsk, cpuset_subsys_id);
2487 retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
2494 put_task_struct(tsk);
2501 static int cpuset_open(struct inode *inode, struct file *file)
2503 struct pid *pid = PROC_I(inode)->pid;
2504 return single_open(file, proc_cpuset_show, pid);
2507 const struct file_operations proc_cpuset_operations = {
2508 .open = cpuset_open,
2510 .llseek = seq_lseek,
2511 .release = single_release,
2513 #endif /* CONFIG_PROC_PID_CPUSET */
2515 /* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */
2516 void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
2518 seq_printf(m, "Cpus_allowed:\t");
2519 seq_cpumask(m, &task->cpus_allowed);
2520 seq_printf(m, "\n");
2521 seq_printf(m, "Cpus_allowed_list:\t");
2522 seq_cpumask_list(m, &task->cpus_allowed);
2523 seq_printf(m, "\n");
2524 seq_printf(m, "Mems_allowed:\t");
2525 seq_nodemask(m, &task->mems_allowed);
2526 seq_printf(m, "\n");
2527 seq_printf(m, "Mems_allowed_list:\t");
2528 seq_nodemask_list(m, &task->mems_allowed);
2529 seq_printf(m, "\n");