nohz: Switch from "extended nohz" to "full nohz" based naming

"Extended nohz" was used as a naming base for the full dynticks
API and Kconfig symbols. It reflects the fact the system tries
to stop the tick in more places than just idle.

But that "extended" name is a bit opaque and vague. Rename it to
"full" makes it clearer what the system tries to do under this
config: try to shutdown the tick anytime it can. The various
constraints that prevent that to happen shouldn't be considered
as fundamental properties of this feature but rather technical
issues that may be solved in the future.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 231698feaddcdf669e5969ec5efd0a3e74bf2130..82365dde00a8eee09e43b295496729b102ddeac7 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1913,8 +1913,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        Valid arguments: on, off
                        Default: on
 
-       nohz_extended=  [KNL,BOOT]
-                       In kernels built with CONFIG_NO_HZ_EXTENDED=y, set
+       nohz_full=      [KNL,BOOT]
+                       In kernels built with CONFIG_NO_HZ_FULL=y, set
                        the specified list of CPUs whose tick will be stopped
                        whenever possible. You need to keep at least one online
                        CPU outside the range to maintain the timekeeping.

diff --git a/include/linux/tick.h b/include/linux/tick.h
index 5e403339ee14ab2f6c571da3335dc09d0644abd2..b4e3b0c9639e7520aaf8e9a9b4e6e39f9722bf33 100644 (file)
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -157,10 +157,10 @@ static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; }
 static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
 # endif /* !CONFIG_NO_HZ_COMMON */
 
-#ifdef CONFIG_NO_HZ_EXTENDED
-extern int tick_nohz_extended_cpu(int cpu);
+#ifdef CONFIG_NO_HZ_FULL
+extern int tick_nohz_full_cpu(int cpu);
 #else
-static inline int tick_nohz_extended_cpu(int cpu) { return 0; }
+static inline int tick_nohz_full_cpu(int cpu) { return 0; }
 #endif
 
 

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9bb397da63d628108d164192b142e96254456812..0f0a5b3fd62c8c6ddeffc2d0ee1ec840f596eafc 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -617,9 +617,9 @@ static void wake_up_idle_cpu(int cpu)
                smp_send_reschedule(cpu);
 }
 
-static bool wake_up_extended_nohz_cpu(int cpu)
+static bool wake_up_full_nohz_cpu(int cpu)
 {
-       if (tick_nohz_extended_cpu(cpu)) {
+       if (tick_nohz_full_cpu(cpu)) {
                if (cpu != smp_processor_id() ||
                    tick_nohz_tick_stopped())
                        smp_send_reschedule(cpu);
@@ -631,7 +631,7 @@ static bool wake_up_extended_nohz_cpu(int cpu)
 
 void wake_up_nohz_cpu(int cpu)
 {
-       if (!wake_up_extended_nohz_cpu(cpu))
+       if (!wake_up_full_nohz_cpu(cpu))
                wake_up_idle_cpu(cpu);
 }
 

diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index cbe64be17d1f1dfcac5276f4b576af077d6ae948..4a17b5069466899a14384d8a102e4c7a676cca64 100644 (file)
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -96,7 +96,7 @@ config NO_HZ_IDLE
 
          Most of the time you want to say Y here.
 
-config NO_HZ_EXTENDED
+config NO_HZ_FULL
        bool "Full dynticks system (tickless single task)"
        # NO_HZ_COMMON dependency
        depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
@@ -115,7 +115,7 @@ config NO_HZ_EXTENDED
         task on the CPU. Chances for running tickless are maximized when
         the task mostly runs in userspace and has few kernel activity.
 
-        You need to fill up the nohz_extended boot parameter with the
+        You need to fill up the nohz_full boot parameter with the
         desired range of dynticks CPUs.
 
         This is implemented at the expense of some overhead in user <-> kernel

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 8a6875cc1879195a8fe828e62e3f57f4e51769fd..a3a3123f6272b74486ea14503b914ac4e6f17160 100644 (file)
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -573,7 +573,7 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
                bc->event_handler = tick_handle_oneshot_broadcast;
 
                /* Take the do_timer update */
-               if (!tick_nohz_extended_cpu(cpu))
+               if (!tick_nohz_full_cpu(cpu))
                        tick_do_timer_cpu = cpu;
 
                /*

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index b7dc0cbdb59bf08b12ac063c62a64fe05e971e82..83f2bd967161460776207c3f4d354c1c0a06fe41 100644 (file)
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -163,7 +163,7 @@ static void tick_setup_device(struct tick_device *td,
                 * this cpu:
                 */
                if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
-                       if (!tick_nohz_extended_cpu(cpu))
+                       if (!tick_nohz_full_cpu(cpu))
                                tick_do_timer_cpu = cpu;
                        else
                                tick_do_timer_cpu = TICK_DO_TIMER_NONE;

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index e057d338daa494a69ca7244e1696a430dffc5161..369b5769fc9722e5e751c45cd3941dadf6a7cb91 100644 (file)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -113,7 +113,7 @@ static void tick_sched_do_timer(ktime_t now)
         * jiffies_lock.
         */
        if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)
-           && !tick_nohz_extended_cpu(cpu))
+           && !tick_nohz_full_cpu(cpu))
                tick_do_timer_cpu = cpu;
 #endif
 
@@ -143,29 +143,29 @@ 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;
+#ifdef CONFIG_NO_HZ_FULL
+static cpumask_var_t nohz_full_mask;
+bool have_nohz_full_mask;
 
-int tick_nohz_extended_cpu(int cpu)
+int tick_nohz_full_cpu(int cpu)
 {
-       if (!have_nohz_extended_mask)
+       if (!have_nohz_full_mask)
                return 0;
 
-       return cpumask_test_cpu(cpu, nohz_extended_mask);
+       return cpumask_test_cpu(cpu, nohz_full_mask);
 }
 
 /* Parse the boot-time nohz CPU list from the kernel parameters. */
-static int __init tick_nohz_extended_setup(char *str)
+static int __init tick_nohz_full_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");
+       alloc_bootmem_cpumask_var(&nohz_full_mask);
+       if (cpulist_parse(str, nohz_full_mask) < 0)
+               pr_warning("NOHZ: Incorrect nohz_full cpumask\n");
        else
-               have_nohz_extended_mask = true;
+               have_nohz_full_mask = true;
        return 1;
 }
-__setup("nohz_extended=", tick_nohz_extended_setup);
+__setup("nohz_full=", tick_nohz_full_setup);
 
 static int __cpuinit tick_nohz_cpu_down_callback(struct notifier_block *nfb,
                                                 unsigned long action,
@@ -179,7 +179,7 @@ static int __cpuinit tick_nohz_cpu_down_callback(struct notifier_block *nfb,
                 * If we handle the timekeeping duty for full dynticks CPUs,
                 * we can't safely shutdown that CPU.
                 */
-               if (have_nohz_extended_mask && tick_do_timer_cpu == cpu)
+               if (have_nohz_full_mask && tick_do_timer_cpu == cpu)
                        return -EINVAL;
                break;
        }
@@ -191,20 +191,20 @@ static int __cpuinit tick_nohz_cpu_down_callback(struct notifier_block *nfb,
  * separations: 0,2,4,6,...
  * This is NR_CPUS + sizeof('\0')
  */
-static char __initdata nohz_ext_buf[NR_CPUS + 1];
+static char __initdata nohz_full_buf[NR_CPUS + 1];
 
-static int __init init_tick_nohz_extended(void)
+static int __init init_tick_nohz_full(void)
 {
        cpumask_var_t online_nohz;
        int cpu;
 
-       if (!have_nohz_extended_mask)
+       if (!have_nohz_full_mask)
                return 0;
 
        cpu_notifier(tick_nohz_cpu_down_callback, 0);
 
        if (!zalloc_cpumask_var(&online_nohz, GFP_KERNEL)) {
-               pr_warning("NO_HZ: Not enough memory to check extended nohz mask\n");
+               pr_warning("NO_HZ: Not enough memory to check full nohz mask\n");
                return -ENOMEM;
        }
 
@@ -215,31 +215,31 @@ static int __init init_tick_nohz_extended(void)
        get_online_cpus();
 
        /* Ensure we keep a CPU outside the dynticks range for timekeeping */
-       cpumask_and(online_nohz, cpu_online_mask, nohz_extended_mask);
+       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_extended range\n");
+                          "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_extended range\n", cpu);
-               cpumask_clear_cpu(cpu, nohz_extended_mask);
+               pr_warning("NO_HZ: Clearing %d from nohz_full range\n", cpu);
+               cpumask_clear_cpu(cpu, nohz_full_mask);
                preempt_enable();
        }
        put_online_cpus();
        free_cpumask_var(online_nohz);
 
-       cpulist_scnprintf(nohz_ext_buf, sizeof(nohz_ext_buf), nohz_extended_mask);
-       pr_info("NO_HZ: Full dynticks CPUs: %s.\n", nohz_ext_buf);
+       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_extended);
+core_initcall(init_tick_nohz_full);
 #else
-#define have_nohz_extended_mask (0)
+#define have_nohz_full_mask (0)
 #endif
 
 /*
@@ -589,7 +589,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
                return false;
        }
 
-       if (have_nohz_extended_mask) {
+       if (have_nohz_full_mask) {
                /*
                 * Keep the tick alive to guarantee timekeeping progression
                 * if there are full dynticks CPUs around