path: root/kernel/time
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authorFrederic Weisbecker <fweisbec@gmail.com>2013-03-27 01:17:22 +0100
committerFrederic Weisbecker <fweisbec@gmail.com>2013-04-19 13:54:16 +0200
commitf98823ac758ba1aa77c6e3f8ad4ef3ad84ee0a7c (patch)
tree069ceb12d981f33d997afd214c2082a6685a2fd0 /kernel/time
parentd1e43fa5f8bb25f83a86a29f11fcfb57ed4d7566 (diff)
nohz: New option to default all CPUs in full dynticks range
Provide a new kernel config that defaults all CPUs to be part of the full dynticks range, except the boot one for timekeeping. This default setting is overriden by the nohz_full= boot option if passed by the user. This is helpful for those who don't need a finegrained range of full dynticks CPU and also for automated testing. Suggested-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time')
2 files changed, 31 insertions, 2 deletions
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 358d601a4fe..99c3f13dd47 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -128,6 +128,16 @@ config NO_HZ_FULL
+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"
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index d71a5f2bd7b..a76e09044f9 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -203,12 +203,31 @@ static int __cpuinit tick_nohz_cpu_down_callback(struct notifier_block *nfb,
static char __initdata nohz_full_buf[NR_CPUS + 1];
+static int tick_nohz_init_all(void)
+ int err = -1;
+ 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;
+ return err;
void __init tick_nohz_init(void)
int cpu;
- if (!have_nohz_full_mask)
- return;
+ if (!have_nohz_full_mask) {
+ if (tick_nohz_init_all() < 0)
+ return;
+ }
cpu_notifier(tick_nohz_cpu_down_callback, 0);