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author | Ingo Molnar <mingo@kernel.org> | 2013-04-21 09:04:42 (GMT) |
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committer | Ingo Molnar <mingo@kernel.org> | 2013-04-21 09:04:42 (GMT) |
commit | 2727872dfe5d273f313f8a0c0dd0fcc58e96cde7 (patch) | |
tree | 069ceb12d981f33d997afd214c2082a6685a2fd0 /kernel/time | |
parent | 65d798f0f9339ae2c4ebe9480e3260b33382a584 (diff) | |
parent | f98823ac758ba1aa77c6e3f8ad4ef3ad84ee0a7c (diff) | |
download | linux-fsl-qoriq-2727872dfe5d273f313f8a0c0dd0fcc58e96cde7.tar.xz |
Merge branch 'timers/nohz-reviewed' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/nohz
Pull full dynticks timekeeping and RCU improvements from Frederic Weisbecker.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/time')
-rw-r--r-- | kernel/time/Kconfig | 10 | ||||
-rw-r--r-- | kernel/time/tick-sched.c | 77 |
2 files changed, 51 insertions, 36 deletions
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 358d601..99c3f13 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -128,6 +128,16 @@ config NO_HZ_FULL endchoice +config NO_HZ_FULL_ALL + bool "Full dynticks system on all CPUs by default" + depends on NO_HZ_FULL + help + If the user doesn't pass the nohz_full boot option to + define the range of full dynticks CPUs, consider that all + CPUs in the system are full dynticks by default. + Note the boot CPU will still be kept outside the range to + handle the timekeeping duty. + config NO_HZ bool "Old Idle dynticks config" depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 369b576..a76e090 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -158,11 +158,21 @@ int tick_nohz_full_cpu(int cpu) /* Parse the boot-time nohz CPU list from the kernel parameters. */ static int __init tick_nohz_full_setup(char *str) { + int cpu; + alloc_bootmem_cpumask_var(&nohz_full_mask); - if (cpulist_parse(str, nohz_full_mask) < 0) + if (cpulist_parse(str, nohz_full_mask) < 0) { pr_warning("NOHZ: Incorrect nohz_full cpumask\n"); - else - have_nohz_full_mask = true; + return 1; + } + + cpu = smp_processor_id(); + if (cpumask_test_cpu(cpu, nohz_full_mask)) { + pr_warning("NO_HZ: Clearing %d from nohz_full range for timekeeping\n", cpu); + cpumask_clear_cpu(cpu, nohz_full_mask); + } + have_nohz_full_mask = true; + return 1; } __setup("nohz_full=", tick_nohz_full_setup); @@ -193,51 +203,46 @@ static int __cpuinit tick_nohz_cpu_down_callback(struct notifier_block *nfb, */ static char __initdata nohz_full_buf[NR_CPUS + 1]; -static int __init init_tick_nohz_full(void) +static int tick_nohz_init_all(void) { - cpumask_var_t online_nohz; - int cpu; + int err = -1; - if (!have_nohz_full_mask) - return 0; +#ifdef CONFIG_NO_HZ_FULL_ALL + if (!alloc_cpumask_var(&nohz_full_mask, GFP_KERNEL)) { + pr_err("NO_HZ: Can't allocate full dynticks cpumask\n"); + return err; + } + err = 0; + cpumask_setall(nohz_full_mask); + cpumask_clear_cpu(smp_processor_id(), nohz_full_mask); + have_nohz_full_mask = true; +#endif + return err; +} - cpu_notifier(tick_nohz_cpu_down_callback, 0); +void __init tick_nohz_init(void) +{ + int cpu; - if (!zalloc_cpumask_var(&online_nohz, GFP_KERNEL)) { - pr_warning("NO_HZ: Not enough memory to check full nohz mask\n"); - return -ENOMEM; + if (!have_nohz_full_mask) { + if (tick_nohz_init_all() < 0) + return; } - /* - * CPUs can probably not be concurrently offlined on initcall time. - * But we are paranoid, aren't we? - */ - get_online_cpus(); + cpu_notifier(tick_nohz_cpu_down_callback, 0); - /* Ensure we keep a CPU outside the dynticks range for timekeeping */ - cpumask_and(online_nohz, cpu_online_mask, nohz_full_mask); - if (cpumask_equal(online_nohz, cpu_online_mask)) { - pr_warning("NO_HZ: Must keep at least one online CPU " - "out of nohz_full range\n"); - /* - * We know the current CPU doesn't have its tick stopped. - * Let's use it for the timekeeping duty. - */ - preempt_disable(); - cpu = smp_processor_id(); - pr_warning("NO_HZ: Clearing %d from nohz_full range\n", cpu); - cpumask_clear_cpu(cpu, nohz_full_mask); - preempt_enable(); + /* Make sure full dynticks CPU are also RCU nocbs */ + for_each_cpu(cpu, nohz_full_mask) { + if (!rcu_is_nocb_cpu(cpu)) { + pr_warning("NO_HZ: CPU %d is not RCU nocb: " + "cleared from nohz_full range", cpu); + cpumask_clear_cpu(cpu, nohz_full_mask); + } } - put_online_cpus(); - free_cpumask_var(online_nohz); cpulist_scnprintf(nohz_full_buf, sizeof(nohz_full_buf), nohz_full_mask); pr_info("NO_HZ: Full dynticks CPUs: %s.\n", nohz_full_buf); - - return 0; } -core_initcall(init_tick_nohz_full); #else #define have_nohz_full_mask (0) #endif |