1 files changed, 74 insertions, 6 deletions

diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 24510d84efd7..e4c07b0692bb 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -64,20 +64,88 @@ config GENERIC_CMOS_UPDATE
 if GENERIC_CLOCKEVENTS
 menu "Timers subsystem"
 
-# Core internal switch. Selected by NO_HZ / HIGH_RES_TIMERS. This is
+# Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
 # only related to the tick functionality. Oneshot clockevent devices
 # are supported independ of this.
 config TICK_ONESHOT
         bool
 
-config NO_HZ
-        bool "Tickless System (Dynamic Ticks)"
+config NO_HZ_COMMON
+        bool
         depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
         select TICK_ONESHOT
+
+choice
+        prompt "Timer tick handling"
+        default NO_HZ_IDLE if NO_HZ
+
+config HZ_PERIODIC
+        bool "Periodic timer ticks (constant rate, no dynticks)"
+        help
+          This option keeps the tick running periodically at a constant
+          rate, even when the CPU doesn't need it.
+
+config NO_HZ_IDLE
+        bool "Idle dynticks system (tickless idle)"
+        depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
+        select NO_HZ_COMMON
+        help
+          This option enables a tickless idle system: timer interrupts
+          will only trigger on an as-needed basis when the system is idle.
+          This is usually interesting for energy saving.
+
+          Most of the time you want to say Y here.
+
+config NO_HZ_FULL
+        bool "Full dynticks system (tickless)"
+        # NO_HZ_COMMON dependency
+        depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
+        # We need at least one periodic CPU for timekeeping
+        depends on SMP
+        # RCU_USER_QS dependency
+        depends on HAVE_CONTEXT_TRACKING
+        # VIRT_CPU_ACCOUNTING_GEN dependency
+        depends on 64BIT
+        select NO_HZ_COMMON
+        select RCU_USER_QS
+        select RCU_NOCB_CPU
+        select VIRT_CPU_ACCOUNTING_GEN
+        select CONTEXT_TRACKING_FORCE
+        select IRQ_WORK
+        help
+         Adaptively try to shutdown the tick whenever possible, even when
+         the CPU is running tasks. Typically this requires running a single
+         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_full boot parameter with the
+         desired range of dynticks CPUs.
+
+         This is implemented at the expense of some overhead in user <-> kernel
+         transitions: syscalls, exceptions and interrupts. Even when it's
+         dynamically off.
+
+         Say N.
+
+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
         help
-          This option enables a tickless system: timer interrupts will
-          only trigger on an as-needed basis both when the system is
-          busy and when the system is idle.
+          This is the old config entry that enables dynticks idle.
+          We keep it around for a little while to enforce backward
+          compatibility with older config files.
 
 config HIGH_RES_TIMERS
         bool "High Resolution Timer Support"