kernel/sched/isolation.c

   1 /*
   2  *  Housekeeping management. Manage the targets for routine code that can run on
   3  *  any CPU: unbound workqueues, timers, kthreads and any offloadable work.
   4  *
   5  * Copyright (C) 2017 Red Hat, Inc., Frederic Weisbecker
   6  *
   7  */
   8
   9 #include <linux/sched/isolation.h>
  10 #include <linux/tick.h>
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13
  14 static cpumask_var_t housekeeping_mask;
  15
  16 int housekeeping_any_cpu(void)
  17 {
  18         if (tick_nohz_full_enabled())
  19                 return cpumask_any_and(housekeeping_mask, cpu_online_mask);
  20
  21         return smp_processor_id();
  22 }
  23 EXPORT_SYMBOL_GPL(housekeeping_any_cpu);
  24
  25 const struct cpumask *housekeeping_cpumask(void)
  26 {
  27         if (tick_nohz_full_enabled())
  28                 return housekeeping_mask;
  29
  30         return cpu_possible_mask;
  31 }
  32 EXPORT_SYMBOL_GPL(housekeeping_cpumask);
  33
  34 void housekeeping_affine(struct task_struct *t)
  35 {
  36         if (tick_nohz_full_enabled())
  37                 set_cpus_allowed_ptr(t, housekeeping_mask);
  38 }
  39 EXPORT_SYMBOL_GPL(housekeeping_affine);
  40
  41 bool housekeeping_test_cpu(int cpu)
  42 {
  43         if (tick_nohz_full_enabled())
  44                 return cpumask_test_cpu(cpu, housekeeping_mask);
  45
  46         return true;
  47 }
  48 EXPORT_SYMBOL_GPL(housekeeping_test_cpu);
  49
  50 void __init housekeeping_init(void)
  51 {
  52         if (!tick_nohz_full_enabled())
  53                 return;
  54
  55         if (!alloc_cpumask_var(&housekeeping_mask, GFP_KERNEL)) {
  56                 WARN(1, "NO_HZ: Can't allocate not-full dynticks cpumask\n");
  57                 cpumask_clear(tick_nohz_full_mask);
  58                 tick_nohz_full_running = false;
  59                 return;
  60         }
  61
  62         cpumask_andnot(housekeeping_mask,
  63                        cpu_possible_mask, tick_nohz_full_mask);
  64
  65         /* We need at least one CPU to handle housekeeping work */
  66         WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
  67 }