nohz: New option to default all CPUs in full dynticks range (f98823ac) · Commits · 戴 / test

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>

kernel/time/Kconfig

+10 −0

Original line number	Diff line number	Diff line
		@@ -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

kernel/time/tick-sched.c

+21 −2

Original line number	Diff line number	Diff line
		@@ -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;

		#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;
		}

		void __init tick_nohz_init(void)
		{
		int cpu;

		if (!have_nohz_full_mask)
		if (!have_nohz_full_mask) {
		if (tick_nohz_init_all() < 0)
		return;
		}

		cpu_notifier(tick_nohz_cpu_down_callback, 0);

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