diff options
Diffstat (limited to 'kernel/time/tick-sched.c')
| -rw-r--r-- | kernel/time/tick-sched.c | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index a19a39952c1..79c275f08b7 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -142,6 +142,68 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) profile_tick(CPU_PROFILING); } +#ifdef CONFIG_NO_HZ_EXTENDED +static cpumask_var_t nohz_extended_mask; +bool have_nohz_extended_mask; + +int tick_nohz_extended_cpu(int cpu) +{ + if (!have_nohz_extended_mask) + return 0; + + return cpumask_test_cpu(cpu, nohz_extended_mask); +} + +/* Parse the boot-time nohz CPU list from the kernel parameters. */ +static int __init tick_nohz_extended_setup(char *str) +{ + alloc_bootmem_cpumask_var(&nohz_extended_mask); + if (cpulist_parse(str, nohz_extended_mask) < 0) + pr_warning("NOHZ: Incorrect nohz_extended cpumask\n"); + else + have_nohz_extended_mask = true; + return 1; +} +__setup("nohz_extended=", tick_nohz_extended_setup); + +static int __init init_tick_nohz_extended(void) +{ + cpumask_var_t online_nohz; + int cpu; + + if (!have_nohz_extended_mask) + return 0; + + if (!zalloc_cpumask_var(&online_nohz, GFP_KERNEL)) { + pr_warning("NO_HZ: Not enough memory to check extended nohz mask\n"); + return -ENOMEM; + } + + /* + * CPUs can probably not be concurrently offlined on initcall time. + * But we are paranoid, aren't we? + */ + get_online_cpus(); + + /* Ensure we keep a CPU outside the dynticks range for timekeeping */ + cpumask_and(online_nohz, cpu_online_mask, nohz_extended_mask); + if (cpumask_equal(online_nohz, cpu_online_mask)) { + cpu = cpumask_any(cpu_online_mask); + pr_warning("NO_HZ: Must keep at least one online CPU " + "out of nohz_extended range\n"); + pr_warning("NO_HZ: Clearing %d from nohz_extended range\n", cpu); + cpumask_clear_cpu(cpu, nohz_extended_mask); + } + put_online_cpus(); + free_cpumask_var(online_nohz); + + return 0; +} +core_initcall(init_tick_nohz_extended); +#else +#define have_nohz_extended_mask (0) +#endif + /* * NOHZ - aka dynamic tick functionality */ |